CRITICAL (6)
SSL Version 2 and 3 Protocol Detection
Plugin ID: 20007
Port: tcp/25
The remote service accepts connections encrypted using SSL 2.0 and/or
SSL 3.0. These versions of SSL are affected by several cryptographic
flaws, including:
- An insecure padding scheme with CBC ciphers.
- Insecure session renegotiation and resumption schemes.
An attacker can exploit these flaws to conduct man-in-the-middle
attacks or to decrypt communications between the affected service and
clients.
Although SSL/TLS has a secure means for choosing the highest supported
version of the protocol (so that these versions will be used only if
the client or server support nothing better), many web browsers
implement this in an unsafe way that allows an attacker to downgrade
a connection (such as in POODLE). Therefore, it is recommended that
these protocols be disabled entirely.
NIST has determined that SSL 3.0 is no longer acceptable for secure
communications. As of the date of enforcement found in PCI DSS v3.1,
any version of SSL will not meet the PCI SSC's definition of 'strong
cryptography'.
Javasolt megoldás
Consult the application's documentation to disable SSL 2.0 and 3.0.
Use TLS 1.2 (with approved cipher suites) or higher instead.
SSL Version 2 and 3 Protocol Detection
Plugin ID: 20007
Port: tcp/443
The remote service accepts connections encrypted using SSL 2.0 and/or
SSL 3.0. These versions of SSL are affected by several cryptographic
flaws, including:
- An insecure padding scheme with CBC ciphers.
- Insecure session renegotiation and resumption schemes.
An attacker can exploit these flaws to conduct man-in-the-middle
attacks or to decrypt communications between the affected service and
clients.
Although SSL/TLS has a secure means for choosing the highest supported
version of the protocol (so that these versions will be used only if
the client or server support nothing better), many web browsers
implement this in an unsafe way that allows an attacker to downgrade
a connection (such as in POODLE). Therefore, it is recommended that
these protocols be disabled entirely.
NIST has determined that SSL 3.0 is no longer acceptable for secure
communications. As of the date of enforcement found in PCI DSS v3.1,
any version of SSL will not meet the PCI SSC's definition of 'strong
cryptography'.
Javasolt megoldás
Consult the application's documentation to disable SSL 2.0 and 3.0.
Use TLS 1.2 (with approved cipher suites) or higher instead.
SSL Version 2 and 3 Protocol Detection
Plugin ID: 20007
Port: tcp/465
The remote service accepts connections encrypted using SSL 2.0 and/or
SSL 3.0. These versions of SSL are affected by several cryptographic
flaws, including:
- An insecure padding scheme with CBC ciphers.
- Insecure session renegotiation and resumption schemes.
An attacker can exploit these flaws to conduct man-in-the-middle
attacks or to decrypt communications between the affected service and
clients.
Although SSL/TLS has a secure means for choosing the highest supported
version of the protocol (so that these versions will be used only if
the client or server support nothing better), many web browsers
implement this in an unsafe way that allows an attacker to downgrade
a connection (such as in POODLE). Therefore, it is recommended that
these protocols be disabled entirely.
NIST has determined that SSL 3.0 is no longer acceptable for secure
communications. As of the date of enforcement found in PCI DSS v3.1,
any version of SSL will not meet the PCI SSC's definition of 'strong
cryptography'.
Javasolt megoldás
Consult the application's documentation to disable SSL 2.0 and 3.0.
Use TLS 1.2 (with approved cipher suites) or higher instead.
SSL Version 2 and 3 Protocol Detection
Plugin ID: 20007
Port: tcp/993
The remote service accepts connections encrypted using SSL 2.0 and/or
SSL 3.0. These versions of SSL are affected by several cryptographic
flaws, including:
- An insecure padding scheme with CBC ciphers.
- Insecure session renegotiation and resumption schemes.
An attacker can exploit these flaws to conduct man-in-the-middle
attacks or to decrypt communications between the affected service and
clients.
Although SSL/TLS has a secure means for choosing the highest supported
version of the protocol (so that these versions will be used only if
the client or server support nothing better), many web browsers
implement this in an unsafe way that allows an attacker to downgrade
a connection (such as in POODLE). Therefore, it is recommended that
these protocols be disabled entirely.
NIST has determined that SSL 3.0 is no longer acceptable for secure
communications. As of the date of enforcement found in PCI DSS v3.1,
any version of SSL will not meet the PCI SSC's definition of 'strong
cryptography'.
Javasolt megoldás
Consult the application's documentation to disable SSL 2.0 and 3.0.
Use TLS 1.2 (with approved cipher suites) or higher instead.
IBM Domino SEoL (8.5.x)
Plugin ID: 171345
Port: tcp/25
According to its version, IBM Domino is 8.5.x. It is, therefore, no longer maintained by its vendor or provider.
Lack of support implies that no new security patches for the product will be released by the vendor. As a result, it may
contain security vulnerabilities.
Javasolt megoldás
Upgrade to a version of IBM Domino that is currently supported.
IBM Domino SEoL (8.5.x)
Plugin ID: 171345
Port: tcp/465
According to its version, IBM Domino is 8.5.x. It is, therefore, no longer maintained by its vendor or provider.
Lack of support implies that no new security patches for the product will be released by the vendor. As a result, it may
contain security vulnerabilities.
Javasolt megoldás
Upgrade to a version of IBM Domino that is currently supported.
HIGH (6)
SSL Medium Strength Cipher Suites Supported (SWEET32)
The remote host supports the use of SSL ciphers that offer medium
strength encryption. Nessus regards medium strength as any encryption
that uses key lengths at least 64 bits and less than 112 bits, or
else that uses the 3DES encryption suite.
Note that it is considerably easier to circumvent medium strength
encryption if the attacker is on the same physical network.
Javasolt megoldás
Reconfigure the affected application if possible to avoid use of
medium strength ciphers.
SSL Medium Strength Cipher Suites Supported (SWEET32)
The remote host supports the use of SSL ciphers that offer medium
strength encryption. Nessus regards medium strength as any encryption
that uses key lengths at least 64 bits and less than 112 bits, or
else that uses the 3DES encryption suite.
Note that it is considerably easier to circumvent medium strength
encryption if the attacker is on the same physical network.
Javasolt megoldás
Reconfigure the affected application if possible to avoid use of
medium strength ciphers.
SSL Medium Strength Cipher Suites Supported (SWEET32)
The remote host supports the use of SSL ciphers that offer medium
strength encryption. Nessus regards medium strength as any encryption
that uses key lengths at least 64 bits and less than 112 bits, or
else that uses the 3DES encryption suite.
Note that it is considerably easier to circumvent medium strength
encryption if the attacker is on the same physical network.
Javasolt megoldás
Reconfigure the affected application if possible to avoid use of
medium strength ciphers.
SSL Medium Strength Cipher Suites Supported (SWEET32)
The remote host supports the use of SSL ciphers that offer medium
strength encryption. Nessus regards medium strength as any encryption
that uses key lengths at least 64 bits and less than 112 bits, or
else that uses the 3DES encryption suite.
Note that it is considerably easier to circumvent medium strength
encryption if the attacker is on the same physical network.
Javasolt megoldás
Reconfigure the affected application if possible to avoid use of
medium strength ciphers.
OpenSSH < 9.8 RCE
The version of OpenSSH installed on the remote host is prior to 9.8. It is, therefore, affected by a vulnerability as
referenced in the release-9.8 advisory.
- This release contains fixes for two security problems, one critical and one minor. 1) Race condition in
sshd(8) A critical vulnerability in sshd(8) was present in Portable OpenSSH versions between 8.5p1 and
9.7p1 (inclusive) that may allow arbitrary code execution with root privileges. Successful exploitation
has been demonstrated on 32-bit Linux/glibc systems with ASLR. Under lab conditions, the attack requires
on average 6-8 hours of continuous connections up to the maximum the server will accept. Exploitation on
64-bit systems is believed to be possible but has not been demonstrated at this time. It's likely that
these attacks will be improved upon. Exploitation on non-glibc systems is conceivable but has not been
examined. Systems that lack ASLR or users of downstream Linux distributions that have modified OpenSSH to
disable per-connection ASLR re-randomisation (yes - this is a thing, no - we don't understand why) may
potentially have an easier path to exploitation. OpenBSD is not vulnerable. We thank the Qualys Security
Advisory Team for discovering, reporting and demonstrating exploitability of this problem, and for
providing detailed feedback on additional mitigation measures. 2) Logic error in ssh(1)
ObscureKeystrokeTiming In OpenSSH version 9.5 through 9.7 (inclusive), when connected to an OpenSSH server
version 9.5 or later, a logic error in the ssh(1) ObscureKeystrokeTiming feature (on by default) rendered
this feature ineffective - a passive observer could still detect which network packets contained real
keystrokes when the countermeasure was active because both fake and real keystroke packets were being sent
unconditionally. This bug was Daniel Hugenroth and Alastair Beresford of the University of Cambridge
Computer Lab. Worse, the unconditional sending of both fake and real keystroke packets broke another long-
standing timing attack mitigation. Since OpenSSH 2.9.9 sshd(8) has sent fake keystoke echo packets for
traffic received on TTYs in echo-off mode, such as when entering a password into su(8) or sudo(8). This
bug rendered these fake keystroke echoes ineffective and could allow a passive observer of a SSH session
to once again detect when echo was off and obtain fairly limited timing information about keystrokes in
this situation (20ms granularity by default). This additional implication of the bug was identified by
Jacky Wei En Kung, Daniel Hugenroth and Alastair Beresford and we thank them for their detailed analysis.
This bug does not affect connections when ObscureKeystrokeTiming was disabled or sessions where no TTY was
requested. (openssh-9.8-1)
Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version
number.
Javasolt megoldás
Upgrade to OpenSSH version 9.8 or later.
OpenSSH < 9.8 RCE
The version of OpenSSH installed on the remote host is prior to 9.8. It is, therefore, affected by a vulnerability as
referenced in the release-9.8 advisory.
- This release contains fixes for two security problems, one critical and one minor. 1) Race condition in
sshd(8) A critical vulnerability in sshd(8) was present in Portable OpenSSH versions between 8.5p1 and
9.7p1 (inclusive) that may allow arbitrary code execution with root privileges. Successful exploitation
has been demonstrated on 32-bit Linux/glibc systems with ASLR. Under lab conditions, the attack requires
on average 6-8 hours of continuous connections up to the maximum the server will accept. Exploitation on
64-bit systems is believed to be possible but has not been demonstrated at this time. It's likely that
these attacks will be improved upon. Exploitation on non-glibc systems is conceivable but has not been
examined. Systems that lack ASLR or users of downstream Linux distributions that have modified OpenSSH to
disable per-connection ASLR re-randomisation (yes - this is a thing, no - we don't understand why) may
potentially have an easier path to exploitation. OpenBSD is not vulnerable. We thank the Qualys Security
Advisory Team for discovering, reporting and demonstrating exploitability of this problem, and for
providing detailed feedback on additional mitigation measures. 2) Logic error in ssh(1)
ObscureKeystrokeTiming In OpenSSH version 9.5 through 9.7 (inclusive), when connected to an OpenSSH server
version 9.5 or later, a logic error in the ssh(1) ObscureKeystrokeTiming feature (on by default) rendered
this feature ineffective - a passive observer could still detect which network packets contained real
keystrokes when the countermeasure was active because both fake and real keystroke packets were being sent
unconditionally. This bug was Daniel Hugenroth and Alastair Beresford of the University of Cambridge
Computer Lab. Worse, the unconditional sending of both fake and real keystroke packets broke another long-
standing timing attack mitigation. Since OpenSSH 2.9.9 sshd(8) has sent fake keystoke echo packets for
traffic received on TTYs in echo-off mode, such as when entering a password into su(8) or sudo(8). This
bug rendered these fake keystroke echoes ineffective and could allow a passive observer of a SSH session
to once again detect when echo was off and obtain fairly limited timing information about keystrokes in
this situation (20ms granularity by default). This additional implication of the bug was identified by
Jacky Wei En Kung, Daniel Hugenroth and Alastair Beresford and we thank them for their detailed analysis.
This bug does not affect connections when ObscureKeystrokeTiming was disabled or sessions where no TTY was
requested. (openssh-9.8-1)
Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version
number.
Javasolt megoldás
Upgrade to OpenSSH version 9.8 or later.
MEDIUM (59)
HTTP TRACE / TRACK Methods Allowed
The remote web server supports the TRACE and/or TRACK methods. TRACE
and TRACK are HTTP methods that are used to debug web server
connections.
Javasolt megoldás
Disable these HTTP methods. Refer to the plugin output for more information.
HTTP TRACE / TRACK Methods Allowed
The remote web server supports the TRACE and/or TRACK methods. TRACE
and TRACK are HTTP methods that are used to debug web server
connections.
Javasolt megoldás
Disable these HTTP methods. Refer to the plugin output for more information.
HTTP TRACE / TRACK Methods Allowed
The remote web server supports the TRACE and/or TRACK methods. TRACE
and TRACK are HTTP methods that are used to debug web server
connections.
Javasolt megoldás
Disable these HTTP methods. Refer to the plugin output for more information.
SSL Certificate Expiry
Plugin ID: 15901
Port: tcp/25
This plugin checks expiry dates of certificates associated with SSL-
enabled services on the target and reports whether any have already
expired.
Javasolt megoldás
Purchase or generate a new SSL certificate to replace the existing
one.
SSL Certificate Expiry
Plugin ID: 15901
Port: tcp/443
This plugin checks expiry dates of certificates associated with SSL-
enabled services on the target and reports whether any have already
expired.
Javasolt megoldás
Purchase or generate a new SSL certificate to replace the existing
one.
SSL Certificate Expiry
Plugin ID: 15901
Port: tcp/465
This plugin checks expiry dates of certificates associated with SSL-
enabled services on the target and reports whether any have already
expired.
Javasolt megoldás
Purchase or generate a new SSL certificate to replace the existing
one.
SSL Certificate Expiry
Plugin ID: 15901
Port: tcp/993
This plugin checks expiry dates of certificates associated with SSL-
enabled services on the target and reports whether any have already
expired.
Javasolt megoldás
Purchase or generate a new SSL certificate to replace the existing
one.
SSL Weak Cipher Suites Supported
Plugin ID: 26928
Port: tcp/443
The remote host supports the use of SSL ciphers that offer weak
encryption.
Note: This is considerably easier to exploit if the attacker is on the
same physical network.
Javasolt megoldás
Reconfigure the affected application, if possible to avoid the use of
weak ciphers.
SSL Weak Cipher Suites Supported
Plugin ID: 26928
Port: tcp/465
The remote host supports the use of SSL ciphers that offer weak
encryption.
Note: This is considerably easier to exploit if the attacker is on the
same physical network.
Javasolt megoldás
Reconfigure the affected application, if possible to avoid the use of
weak ciphers.
SSL Weak Cipher Suites Supported
Plugin ID: 26928
Port: tcp/993
The remote host supports the use of SSL ciphers that offer weak
encryption.
Note: This is considerably easier to exploit if the attacker is on the
same physical network.
Javasolt megoldás
Reconfigure the affected application, if possible to avoid the use of
weak ciphers.
SSL Certificate Signed Using Weak Hashing Algorithm
The remote service uses an SSL certificate chain that has been signed
using a cryptographically weak hashing algorithm (e.g. MD2, MD4, MD5,
or SHA1). These signature algorithms are known to be vulnerable to
collision attacks. An attacker can exploit this to generate another
certificate with the same digital signature, allowing an attacker to
masquerade as the affected service.
Note that this plugin reports all SSL certificate chains signed with
SHA-1 that expire after January 1, 2017 as vulnerable. This is in
accordance with Google's gradual sunsetting of the SHA-1 cryptographic
hash algorithm.
Note that certificates in the chain that are contained in the Nessus
CA database (known_CA.inc) have been ignored.
Javasolt megoldás
Contact the Certificate Authority to have the SSL certificate reissued.
SSL Certificate Signed Using Weak Hashing Algorithm
The remote service uses an SSL certificate chain that has been signed
using a cryptographically weak hashing algorithm (e.g. MD2, MD4, MD5,
or SHA1). These signature algorithms are known to be vulnerable to
collision attacks. An attacker can exploit this to generate another
certificate with the same digital signature, allowing an attacker to
masquerade as the affected service.
Note that this plugin reports all SSL certificate chains signed with
SHA-1 that expire after January 1, 2017 as vulnerable. This is in
accordance with Google's gradual sunsetting of the SHA-1 cryptographic
hash algorithm.
Note that certificates in the chain that are contained in the Nessus
CA database (known_CA.inc) have been ignored.
Javasolt megoldás
Contact the Certificate Authority to have the SSL certificate reissued.
SSL Certificate Signed Using Weak Hashing Algorithm
The remote service uses an SSL certificate chain that has been signed
using a cryptographically weak hashing algorithm (e.g. MD2, MD4, MD5,
or SHA1). These signature algorithms are known to be vulnerable to
collision attacks. An attacker can exploit this to generate another
certificate with the same digital signature, allowing an attacker to
masquerade as the affected service.
Note that this plugin reports all SSL certificate chains signed with
SHA-1 that expire after January 1, 2017 as vulnerable. This is in
accordance with Google's gradual sunsetting of the SHA-1 cryptographic
hash algorithm.
Note that certificates in the chain that are contained in the Nessus
CA database (known_CA.inc) have been ignored.
Javasolt megoldás
Contact the Certificate Authority to have the SSL certificate reissued.
SSL Certificate Signed Using Weak Hashing Algorithm
The remote service uses an SSL certificate chain that has been signed
using a cryptographically weak hashing algorithm (e.g. MD2, MD4, MD5,
or SHA1). These signature algorithms are known to be vulnerable to
collision attacks. An attacker can exploit this to generate another
certificate with the same digital signature, allowing an attacker to
masquerade as the affected service.
Note that this plugin reports all SSL certificate chains signed with
SHA-1 that expire after January 1, 2017 as vulnerable. This is in
accordance with Google's gradual sunsetting of the SHA-1 cryptographic
hash algorithm.
Note that certificates in the chain that are contained in the Nessus
CA database (known_CA.inc) have been ignored.
Javasolt megoldás
Contact the Certificate Authority to have the SSL certificate reissued.
SSL Certificate Signed Using Weak Hashing Algorithm
The remote service uses an SSL certificate chain that has been signed
using a cryptographically weak hashing algorithm (e.g. MD2, MD4, MD5,
or SHA1). These signature algorithms are known to be vulnerable to
collision attacks. An attacker can exploit this to generate another
certificate with the same digital signature, allowing an attacker to
masquerade as the affected service.
Note that this plugin reports all SSL certificate chains signed with
SHA-1 that expire after January 1, 2017 as vulnerable. This is in
accordance with Google's gradual sunsetting of the SHA-1 cryptographic
hash algorithm.
Note that certificates in the chain that are contained in the Nessus
CA database (known_CA.inc) have been ignored.
Javasolt megoldás
Contact the Certificate Authority to have the SSL certificate reissued.
SSL Certificate Signed Using Weak Hashing Algorithm
The remote service uses an SSL certificate chain that has been signed
using a cryptographically weak hashing algorithm (e.g. MD2, MD4, MD5,
or SHA1). These signature algorithms are known to be vulnerable to
collision attacks. An attacker can exploit this to generate another
certificate with the same digital signature, allowing an attacker to
masquerade as the affected service.
Note that this plugin reports all SSL certificate chains signed with
SHA-1 that expire after January 1, 2017 as vulnerable. This is in
accordance with Google's gradual sunsetting of the SHA-1 cryptographic
hash algorithm.
Note that certificates in the chain that are contained in the Nessus
CA database (known_CA.inc) have been ignored.
Javasolt megoldás
Contact the Certificate Authority to have the SSL certificate reissued.
SSL Certificate Signed Using Weak Hashing Algorithm
The remote service uses an SSL certificate chain that has been signed
using a cryptographically weak hashing algorithm (e.g. MD2, MD4, MD5,
or SHA1). These signature algorithms are known to be vulnerable to
collision attacks. An attacker can exploit this to generate another
certificate with the same digital signature, allowing an attacker to
masquerade as the affected service.
Note that this plugin reports all SSL certificate chains signed with
SHA-1 that expire after January 1, 2017 as vulnerable. This is in
accordance with Google's gradual sunsetting of the SHA-1 cryptographic
hash algorithm.
Note that certificates in the chain that are contained in the Nessus
CA database (known_CA.inc) have been ignored.
Javasolt megoldás
Contact the Certificate Authority to have the SSL certificate reissued.
SSL Certificate Signed Using Weak Hashing Algorithm
The remote service uses an SSL certificate chain that has been signed
using a cryptographically weak hashing algorithm (e.g. MD2, MD4, MD5,
or SHA1). These signature algorithms are known to be vulnerable to
collision attacks. An attacker can exploit this to generate another
certificate with the same digital signature, allowing an attacker to
masquerade as the affected service.
Note that this plugin reports all SSL certificate chains signed with
SHA-1 that expire after January 1, 2017 as vulnerable. This is in
accordance with Google's gradual sunsetting of the SHA-1 cryptographic
hash algorithm.
Note that certificates in the chain that are contained in the Nessus
CA database (known_CA.inc) have been ignored.
Javasolt megoldás
Contact the Certificate Authority to have the SSL certificate reissued.
SSL Certificate Cannot Be Trusted
Plugin ID: 51192
Port: tcp/25
The server's X.509 certificate cannot be trusted. This situation can
occur in three different ways, in which the chain of trust can be
broken, as stated below :
- First, the top of the certificate chain sent by the
server might not be descended from a known public
certificate authority. This can occur either when the
top of the chain is an unrecognized, self-signed
certificate, or when intermediate certificates are
missing that would connect the top of the certificate
chain to a known public certificate authority.
- Second, the certificate chain may contain a certificate
that is not valid at the time of the scan. This can
occur either when the scan occurs before one of the
certificate's 'notBefore' dates, or after one of the
certificate's 'notAfter' dates.
- Third, the certificate chain may contain a signature
that either didn't match the certificate's information
or could not be verified. Bad signatures can be fixed by
getting the certificate with the bad signature to be
re-signed by its issuer. Signatures that could not be
verified are the result of the certificate's issuer
using a signing algorithm that Nessus either does not
support or does not recognize.
If the remote host is a public host in production, any break in the
chain makes it more difficult for users to verify the authenticity and
identity of the web server. This could make it easier to carry out
man-in-the-middle attacks against the remote host.
Javasolt megoldás
Purchase or generate a proper SSL certificate for this service.
SSL Certificate Cannot Be Trusted
Plugin ID: 51192
Port: tcp/443
The server's X.509 certificate cannot be trusted. This situation can
occur in three different ways, in which the chain of trust can be
broken, as stated below :
- First, the top of the certificate chain sent by the
server might not be descended from a known public
certificate authority. This can occur either when the
top of the chain is an unrecognized, self-signed
certificate, or when intermediate certificates are
missing that would connect the top of the certificate
chain to a known public certificate authority.
- Second, the certificate chain may contain a certificate
that is not valid at the time of the scan. This can
occur either when the scan occurs before one of the
certificate's 'notBefore' dates, or after one of the
certificate's 'notAfter' dates.
- Third, the certificate chain may contain a signature
that either didn't match the certificate's information
or could not be verified. Bad signatures can be fixed by
getting the certificate with the bad signature to be
re-signed by its issuer. Signatures that could not be
verified are the result of the certificate's issuer
using a signing algorithm that Nessus either does not
support or does not recognize.
If the remote host is a public host in production, any break in the
chain makes it more difficult for users to verify the authenticity and
identity of the web server. This could make it easier to carry out
man-in-the-middle attacks against the remote host.
Javasolt megoldás
Purchase or generate a proper SSL certificate for this service.
SSL Certificate Cannot Be Trusted
Plugin ID: 51192
Port: tcp/465
The server's X.509 certificate cannot be trusted. This situation can
occur in three different ways, in which the chain of trust can be
broken, as stated below :
- First, the top of the certificate chain sent by the
server might not be descended from a known public
certificate authority. This can occur either when the
top of the chain is an unrecognized, self-signed
certificate, or when intermediate certificates are
missing that would connect the top of the certificate
chain to a known public certificate authority.
- Second, the certificate chain may contain a certificate
that is not valid at the time of the scan. This can
occur either when the scan occurs before one of the
certificate's 'notBefore' dates, or after one of the
certificate's 'notAfter' dates.
- Third, the certificate chain may contain a signature
that either didn't match the certificate's information
or could not be verified. Bad signatures can be fixed by
getting the certificate with the bad signature to be
re-signed by its issuer. Signatures that could not be
verified are the result of the certificate's issuer
using a signing algorithm that Nessus either does not
support or does not recognize.
If the remote host is a public host in production, any break in the
chain makes it more difficult for users to verify the authenticity and
identity of the web server. This could make it easier to carry out
man-in-the-middle attacks against the remote host.
Javasolt megoldás
Purchase or generate a proper SSL certificate for this service.
SSL Certificate Cannot Be Trusted
Plugin ID: 51192
Port: tcp/993
The server's X.509 certificate cannot be trusted. This situation can
occur in three different ways, in which the chain of trust can be
broken, as stated below :
- First, the top of the certificate chain sent by the
server might not be descended from a known public
certificate authority. This can occur either when the
top of the chain is an unrecognized, self-signed
certificate, or when intermediate certificates are
missing that would connect the top of the certificate
chain to a known public certificate authority.
- Second, the certificate chain may contain a certificate
that is not valid at the time of the scan. This can
occur either when the scan occurs before one of the
certificate's 'notBefore' dates, or after one of the
certificate's 'notAfter' dates.
- Third, the certificate chain may contain a signature
that either didn't match the certificate's information
or could not be verified. Bad signatures can be fixed by
getting the certificate with the bad signature to be
re-signed by its issuer. Signatures that could not be
verified are the result of the certificate's issuer
using a signing algorithm that Nessus either does not
support or does not recognize.
If the remote host is a public host in production, any break in the
chain makes it more difficult for users to verify the authenticity and
identity of the web server. This could make it easier to carry out
man-in-the-middle attacks against the remote host.
Javasolt megoldás
Purchase or generate a proper SSL certificate for this service.
SMTP Service STARTTLS Plaintext Command Injection
The remote SMTP service contains a software flaw in its STARTTLS
implementation that could allow a remote, unauthenticated attacker to
inject commands during the plaintext protocol phase that will be
executed during the ciphertext protocol phase.
Successful exploitation could allow an attacker to steal a victim's
email or associated SASL (Simple Authentication and Security Layer)
credentials.
Javasolt megoldás
Contact the vendor to see if an update is available.
SMTP Service STARTTLS Plaintext Command Injection
The remote SMTP service contains a software flaw in its STARTTLS
implementation that could allow a remote, unauthenticated attacker to
inject commands during the plaintext protocol phase that will be
executed during the ciphertext protocol phase.
Successful exploitation could allow an attacker to steal a victim's
email or associated SASL (Simple Authentication and Security Layer)
credentials.
Javasolt megoldás
Contact the vendor to see if an update is available.
SMTP Service STARTTLS Plaintext Command Injection
The remote SMTP service contains a software flaw in its STARTTLS
implementation that could allow a remote, unauthenticated attacker to
inject commands during the plaintext protocol phase that will be
executed during the ciphertext protocol phase.
Successful exploitation could allow an attacker to steal a victim's
email or associated SASL (Simple Authentication and Security Layer)
credentials.
Javasolt megoldás
Contact the vendor to see if an update is available.
SMTP Service STARTTLS Plaintext Command Injection
The remote SMTP service contains a software flaw in its STARTTLS
implementation that could allow a remote, unauthenticated attacker to
inject commands during the plaintext protocol phase that will be
executed during the ciphertext protocol phase.
Successful exploitation could allow an attacker to steal a victim's
email or associated SASL (Simple Authentication and Security Layer)
credentials.
Javasolt megoldás
Contact the vendor to see if an update is available.
SMTP Service STARTTLS Plaintext Command Injection
The remote SMTP service contains a software flaw in its STARTTLS
implementation that could allow a remote, unauthenticated attacker to
inject commands during the plaintext protocol phase that will be
executed during the ciphertext protocol phase.
Successful exploitation could allow an attacker to steal a victim's
email or associated SASL (Simple Authentication and Security Layer)
credentials.
Javasolt megoldás
Contact the vendor to see if an update is available.
SMTP Service STARTTLS Plaintext Command Injection
The remote SMTP service contains a software flaw in its STARTTLS
implementation that could allow a remote, unauthenticated attacker to
inject commands during the plaintext protocol phase that will be
executed during the ciphertext protocol phase.
Successful exploitation could allow an attacker to steal a victim's
email or associated SASL (Simple Authentication and Security Layer)
credentials.
Javasolt megoldás
Contact the vendor to see if an update is available.
SSL Self-Signed Certificate
Plugin ID: 57582
Port: tcp/25
The X.509 certificate chain for this service is not signed by a
recognized certificate authority. If the remote host is a public host
in production, this nullifies the use of SSL as anyone could establish
a man-in-the-middle attack against the remote host.
Note that this plugin does not check for certificate chains that end
in a certificate that is not self-signed, but is signed by an
unrecognized certificate authority.
Javasolt megoldás
Purchase or generate a proper SSL certificate for this service.
SSL Self-Signed Certificate
Plugin ID: 57582
Port: tcp/443
The X.509 certificate chain for this service is not signed by a
recognized certificate authority. If the remote host is a public host
in production, this nullifies the use of SSL as anyone could establish
a man-in-the-middle attack against the remote host.
Note that this plugin does not check for certificate chains that end
in a certificate that is not self-signed, but is signed by an
unrecognized certificate authority.
Javasolt megoldás
Purchase or generate a proper SSL certificate for this service.
SSL Self-Signed Certificate
Plugin ID: 57582
Port: tcp/465
The X.509 certificate chain for this service is not signed by a
recognized certificate authority. If the remote host is a public host
in production, this nullifies the use of SSL as anyone could establish
a man-in-the-middle attack against the remote host.
Note that this plugin does not check for certificate chains that end
in a certificate that is not self-signed, but is signed by an
unrecognized certificate authority.
Javasolt megoldás
Purchase or generate a proper SSL certificate for this service.
SSL Self-Signed Certificate
Plugin ID: 57582
Port: tcp/993
The X.509 certificate chain for this service is not signed by a
recognized certificate authority. If the remote host is a public host
in production, this nullifies the use of SSL as anyone could establish
a man-in-the-middle attack against the remote host.
Note that this plugin does not check for certificate chains that end
in a certificate that is not self-signed, but is signed by an
unrecognized certificate authority.
Javasolt megoldás
Purchase or generate a proper SSL certificate for this service.
SSL Certificate Chain Contains Weak RSA Keys
Plugin ID: 60108
Port: tcp/25
At least one of the X.509 certificates sent by the remote host has a
key that is shorter than 1024 bits. Such keys are considered weak due
to advances in available computing power decreasing the time required to
factor cryptographic keys.
Some SSL implementations, notably Microsoft's, may consider this SSL
chain to be invalid due to the length of one or more of the RSA keys it
contains.
Javasolt megoldás
Replace the certificate in the chain with the weak RSA key with a
stronger key, and reissue any certificates it signed.
SSL Certificate Chain Contains Weak RSA Keys
Plugin ID: 60108
Port: tcp/443
At least one of the X.509 certificates sent by the remote host has a
key that is shorter than 1024 bits. Such keys are considered weak due
to advances in available computing power decreasing the time required to
factor cryptographic keys.
Some SSL implementations, notably Microsoft's, may consider this SSL
chain to be invalid due to the length of one or more of the RSA keys it
contains.
Javasolt megoldás
Replace the certificate in the chain with the weak RSA key with a
stronger key, and reissue any certificates it signed.
SSL Certificate Chain Contains Weak RSA Keys
Plugin ID: 60108
Port: tcp/465
At least one of the X.509 certificates sent by the remote host has a
key that is shorter than 1024 bits. Such keys are considered weak due
to advances in available computing power decreasing the time required to
factor cryptographic keys.
Some SSL implementations, notably Microsoft's, may consider this SSL
chain to be invalid due to the length of one or more of the RSA keys it
contains.
Javasolt megoldás
Replace the certificate in the chain with the weak RSA key with a
stronger key, and reissue any certificates it signed.
SSL Certificate Chain Contains Weak RSA Keys
Plugin ID: 60108
Port: tcp/993
At least one of the X.509 certificates sent by the remote host has a
key that is shorter than 1024 bits. Such keys are considered weak due
to advances in available computing power decreasing the time required to
factor cryptographic keys.
Some SSL implementations, notably Microsoft's, may consider this SSL
chain to be invalid due to the length of one or more of the RSA keys it
contains.
Javasolt megoldás
Replace the certificate in the chain with the weak RSA key with a
stronger key, and reissue any certificates it signed.
SSL RC4 Cipher Suites Supported (Bar Mitzvah)
The remote host supports the use of RC4 in one or more cipher suites.
The RC4 cipher is flawed in its generation of a pseudo-random stream
of bytes so that a wide variety of small biases are introduced into
the stream, decreasing its randomness.
If plaintext is repeatedly encrypted (e.g., HTTP cookies), and an
attacker is able to obtain many (i.e., tens of millions) ciphertexts,
the attacker may be able to derive the plaintext.
Javasolt megoldás
Reconfigure the affected application, if possible, to avoid use of RC4
ciphers. Consider using TLS 1.2 with AES-GCM suites subject to browser
and web server support.
SSL RC4 Cipher Suites Supported (Bar Mitzvah)
The remote host supports the use of RC4 in one or more cipher suites.
The RC4 cipher is flawed in its generation of a pseudo-random stream
of bytes so that a wide variety of small biases are introduced into
the stream, decreasing its randomness.
If plaintext is repeatedly encrypted (e.g., HTTP cookies), and an
attacker is able to obtain many (i.e., tens of millions) ciphertexts,
the attacker may be able to derive the plaintext.
Javasolt megoldás
Reconfigure the affected application, if possible, to avoid use of RC4
ciphers. Consider using TLS 1.2 with AES-GCM suites subject to browser
and web server support.
SSL RC4 Cipher Suites Supported (Bar Mitzvah)
The remote host supports the use of RC4 in one or more cipher suites.
The RC4 cipher is flawed in its generation of a pseudo-random stream
of bytes so that a wide variety of small biases are introduced into
the stream, decreasing its randomness.
If plaintext is repeatedly encrypted (e.g., HTTP cookies), and an
attacker is able to obtain many (i.e., tens of millions) ciphertexts,
the attacker may be able to derive the plaintext.
Javasolt megoldás
Reconfigure the affected application, if possible, to avoid use of RC4
ciphers. Consider using TLS 1.2 with AES-GCM suites subject to browser
and web server support.
SSL RC4 Cipher Suites Supported (Bar Mitzvah)
The remote host supports the use of RC4 in one or more cipher suites.
The RC4 cipher is flawed in its generation of a pseudo-random stream
of bytes so that a wide variety of small biases are introduced into
the stream, decreasing its randomness.
If plaintext is repeatedly encrypted (e.g., HTTP cookies), and an
attacker is able to obtain many (i.e., tens of millions) ciphertexts,
the attacker may be able to derive the plaintext.
Javasolt megoldás
Reconfigure the affected application, if possible, to avoid use of RC4
ciphers. Consider using TLS 1.2 with AES-GCM suites subject to browser
and web server support.
SSL RC4 Cipher Suites Supported (Bar Mitzvah)
The remote host supports the use of RC4 in one or more cipher suites.
The RC4 cipher is flawed in its generation of a pseudo-random stream
of bytes so that a wide variety of small biases are introduced into
the stream, decreasing its randomness.
If plaintext is repeatedly encrypted (e.g., HTTP cookies), and an
attacker is able to obtain many (i.e., tens of millions) ciphertexts,
the attacker may be able to derive the plaintext.
Javasolt megoldás
Reconfigure the affected application, if possible, to avoid use of RC4
ciphers. Consider using TLS 1.2 with AES-GCM suites subject to browser
and web server support.
SSL RC4 Cipher Suites Supported (Bar Mitzvah)
The remote host supports the use of RC4 in one or more cipher suites.
The RC4 cipher is flawed in its generation of a pseudo-random stream
of bytes so that a wide variety of small biases are introduced into
the stream, decreasing its randomness.
If plaintext is repeatedly encrypted (e.g., HTTP cookies), and an
attacker is able to obtain many (i.e., tens of millions) ciphertexts,
the attacker may be able to derive the plaintext.
Javasolt megoldás
Reconfigure the affected application, if possible, to avoid use of RC4
ciphers. Consider using TLS 1.2 with AES-GCM suites subject to browser
and web server support.
SSL RC4 Cipher Suites Supported (Bar Mitzvah)
The remote host supports the use of RC4 in one or more cipher suites.
The RC4 cipher is flawed in its generation of a pseudo-random stream
of bytes so that a wide variety of small biases are introduced into
the stream, decreasing its randomness.
If plaintext is repeatedly encrypted (e.g., HTTP cookies), and an
attacker is able to obtain many (i.e., tens of millions) ciphertexts,
the attacker may be able to derive the plaintext.
Javasolt megoldás
Reconfigure the affected application, if possible, to avoid use of RC4
ciphers. Consider using TLS 1.2 with AES-GCM suites subject to browser
and web server support.
SSL RC4 Cipher Suites Supported (Bar Mitzvah)
The remote host supports the use of RC4 in one or more cipher suites.
The RC4 cipher is flawed in its generation of a pseudo-random stream
of bytes so that a wide variety of small biases are introduced into
the stream, decreasing its randomness.
If plaintext is repeatedly encrypted (e.g., HTTP cookies), and an
attacker is able to obtain many (i.e., tens of millions) ciphertexts,
the attacker may be able to derive the plaintext.
Javasolt megoldás
Reconfigure the affected application, if possible, to avoid use of RC4
ciphers. Consider using TLS 1.2 with AES-GCM suites subject to browser
and web server support.
IBM Lotus Domino 8.5.x Multiple Vulnerabilities
According to its banner, the version of Lotus Domino on the remote host
is 8.5.x and is, therefore, affected by the following vulnerabilities :
- Some scripts inside the Web Help application are
vulnerable to open redirect attacks. (CVE-2012-2159)
- The Web Help component contains a reflected cross-site
scripting vulnerability. (CVE-2012-2161)
- User-input validation errors exist related to the
'Web Administrator' client as well as the 'Src'
parameter and 'x.nsf' script that could allow cross-site
scripting attacks. (CVE-2013-0488, BID 58715)
- A user-input validation error exists related to the
'Web Administrator' client that could allow cross-site
request forgery attacks. (CVE-2013-0489)
Javasolt megoldás
Upgrade to Lotus Domino 9.0 or later.
IBM Lotus Domino 8.5.x Multiple Vulnerabilities
According to its banner, the version of Lotus Domino on the remote host
is 8.5.x and is, therefore, affected by the following vulnerabilities :
- Some scripts inside the Web Help application are
vulnerable to open redirect attacks. (CVE-2012-2159)
- The Web Help component contains a reflected cross-site
scripting vulnerability. (CVE-2012-2161)
- User-input validation errors exist related to the
'Web Administrator' client as well as the 'Src'
parameter and 'x.nsf' script that could allow cross-site
scripting attacks. (CVE-2013-0488, BID 58715)
- A user-input validation error exists related to the
'Web Administrator' client that could allow cross-site
request forgery attacks. (CVE-2013-0489)
Javasolt megoldás
Upgrade to Lotus Domino 9.0 or later.
IBM Lotus Domino 8.5.x Multiple Vulnerabilities
According to its banner, the version of Lotus Domino on the remote host
is 8.5.x and is, therefore, affected by the following vulnerabilities :
- Some scripts inside the Web Help application are
vulnerable to open redirect attacks. (CVE-2012-2159)
- The Web Help component contains a reflected cross-site
scripting vulnerability. (CVE-2012-2161)
- User-input validation errors exist related to the
'Web Administrator' client as well as the 'Src'
parameter and 'x.nsf' script that could allow cross-site
scripting attacks. (CVE-2013-0488, BID 58715)
- A user-input validation error exists related to the
'Web Administrator' client that could allow cross-site
request forgery attacks. (CVE-2013-0489)
Javasolt megoldás
Upgrade to Lotus Domino 9.0 or later.
IBM Lotus Domino 8.5.x Multiple Vulnerabilities
According to its banner, the version of Lotus Domino on the remote host
is 8.5.x and is, therefore, affected by the following vulnerabilities :
- Some scripts inside the Web Help application are
vulnerable to open redirect attacks. (CVE-2012-2159)
- The Web Help component contains a reflected cross-site
scripting vulnerability. (CVE-2012-2161)
- User-input validation errors exist related to the
'Web Administrator' client as well as the 'Src'
parameter and 'x.nsf' script that could allow cross-site
scripting attacks. (CVE-2013-0488, BID 58715)
- A user-input validation error exists related to the
'Web Administrator' client that could allow cross-site
request forgery attacks. (CVE-2013-0489)
Javasolt megoldás
Upgrade to Lotus Domino 9.0 or later.
SSL/TLS EXPORT_RSA <= 512-bit Cipher Suites Supported (FREAK)
The remote host supports EXPORT_RSA cipher suites with keys less than
or equal to 512 bits. An attacker can factor a 512-bit RSA modulus in
a short amount of time.
A man-in-the middle attacker may be able to downgrade the session to
use EXPORT_RSA cipher suites (e.g. CVE-2015-0204). Thus, it is
recommended to remove support for weak cipher suites.
Javasolt megoldás
Reconfigure the service to remove support for EXPORT_RSA cipher
suites.
SSL/TLS EXPORT_RSA <= 512-bit Cipher Suites Supported (FREAK)
The remote host supports EXPORT_RSA cipher suites with keys less than
or equal to 512 bits. An attacker can factor a 512-bit RSA modulus in
a short amount of time.
A man-in-the middle attacker may be able to downgrade the session to
use EXPORT_RSA cipher suites (e.g. CVE-2015-0204). Thus, it is
recommended to remove support for weak cipher suites.
Javasolt megoldás
Reconfigure the service to remove support for EXPORT_RSA cipher
suites.
SSL/TLS EXPORT_RSA <= 512-bit Cipher Suites Supported (FREAK)
The remote host supports EXPORT_RSA cipher suites with keys less than
or equal to 512 bits. An attacker can factor a 512-bit RSA modulus in
a short amount of time.
A man-in-the middle attacker may be able to downgrade the session to
use EXPORT_RSA cipher suites (e.g. CVE-2015-0204). Thus, it is
recommended to remove support for weak cipher suites.
Javasolt megoldás
Reconfigure the service to remove support for EXPORT_RSA cipher
suites.
TLS Version 1.0 Protocol Detection
Plugin ID: 104743
Port: tcp/25
The remote service accepts connections encrypted using TLS 1.0. TLS 1.0 has a
number of cryptographic design flaws. Modern implementations of TLS 1.0
mitigate these problems, but newer versions of TLS like 1.2 and 1.3 are
designed against these flaws and should be used whenever possible.
As of March 31, 2020, Endpoints that aren’t enabled for TLS 1.2
and higher will no longer function properly with major web browsers and major vendors.
PCI DSS v3.2 requires that TLS 1.0 be disabled entirely by June 30,
2018, except for POS POI terminals (and the SSL/TLS termination
points to which they connect) that can be verified as not being
susceptible to any known exploits.
Javasolt megoldás
Enable support for TLS 1.2 and 1.3, and disable support for TLS 1.0.
TLS Version 1.0 Protocol Detection
Plugin ID: 104743
Port: tcp/443
The remote service accepts connections encrypted using TLS 1.0. TLS 1.0 has a
number of cryptographic design flaws. Modern implementations of TLS 1.0
mitigate these problems, but newer versions of TLS like 1.2 and 1.3 are
designed against these flaws and should be used whenever possible.
As of March 31, 2020, Endpoints that aren’t enabled for TLS 1.2
and higher will no longer function properly with major web browsers and major vendors.
PCI DSS v3.2 requires that TLS 1.0 be disabled entirely by June 30,
2018, except for POS POI terminals (and the SSL/TLS termination
points to which they connect) that can be verified as not being
susceptible to any known exploits.
Javasolt megoldás
Enable support for TLS 1.2 and 1.3, and disable support for TLS 1.0.
TLS Version 1.0 Protocol Detection
Plugin ID: 104743
Port: tcp/465
The remote service accepts connections encrypted using TLS 1.0. TLS 1.0 has a
number of cryptographic design flaws. Modern implementations of TLS 1.0
mitigate these problems, but newer versions of TLS like 1.2 and 1.3 are
designed against these flaws and should be used whenever possible.
As of March 31, 2020, Endpoints that aren’t enabled for TLS 1.2
and higher will no longer function properly with major web browsers and major vendors.
PCI DSS v3.2 requires that TLS 1.0 be disabled entirely by June 30,
2018, except for POS POI terminals (and the SSL/TLS termination
points to which they connect) that can be verified as not being
susceptible to any known exploits.
Javasolt megoldás
Enable support for TLS 1.2 and 1.3, and disable support for TLS 1.0.
TLS Version 1.0 Protocol Detection
Plugin ID: 104743
Port: tcp/993
The remote service accepts connections encrypted using TLS 1.0. TLS 1.0 has a
number of cryptographic design flaws. Modern implementations of TLS 1.0
mitigate these problems, but newer versions of TLS like 1.2 and 1.3 are
designed against these flaws and should be used whenever possible.
As of March 31, 2020, Endpoints that aren’t enabled for TLS 1.2
and higher will no longer function properly with major web browsers and major vendors.
PCI DSS v3.2 requires that TLS 1.0 be disabled entirely by June 30,
2018, except for POS POI terminals (and the SSL/TLS termination
points to which they connect) that can be verified as not being
susceptible to any known exploits.
Javasolt megoldás
Enable support for TLS 1.2 and 1.3, and disable support for TLS 1.0.
OpenSSH < 9.6 Multiple Vulnerabilities
The version of OpenSSH installed on the remote host is prior to 9.6. It is, therefore, affected by multiple
vulnerabilities as referenced in the release-9.6 advisory.
- ssh(1), sshd(8): implement protocol extensions to thwart the so-called Terrapin attack discovered by
Fabian Bumer, Marcus Brinkmann and Jrg Schwenk. This attack allows a MITM to effect a limited break of
the integrity of the early encrypted SSH transport protocol by sending extra messages prior to the
commencement of encryption, and deleting an equal number of consecutive messages immediately after
encryption starts. A peer SSH client/server would not be able to detect that messages were deleted. While
cryptographically novel, the security impact of this attack is fortunately very limited as it only allows
deletion of consecutive messages, and deleting most messages at this stage of the protocol prevents user
user authentication from proceeding and results in a stuck connection. The most serious identified impact
is that it lets a MITM to delete the SSH2_MSG_EXT_INFO message sent before authentication starts, allowing
the attacker to disable a subset of the keystroke timing obfuscation features introduced in OpenSSH 9.5.
There is no other discernable impact to session secrecy or session integrity. OpenSSH 9.6 addresses this
protocol weakness through a new strict KEX protocol extension that will be automatically enabled when
both the client and server support it. This extension makes two changes to the SSH transport protocol to
improve the integrity of the initial key exchange. Firstly, it requires endpoints to terminate the
connection if any unnecessary or unexpected message is received during key exchange (including messages
that were previously legal but not strictly required like SSH2_MSG_DEBUG). This removes most malleability
from the early protocol. Secondly, it resets the Message Authentication Code counter at the conclusion of
each key exchange, preventing previously inserted messages from being able to make persistent changes to
the sequence number across completion of a key exchange. Either of these changes should be sufficient to
thwart the Terrapin Attack. More details of these changes are in the PROTOCOL file in the OpenSSH source
distribition. (CVE-2023-48795)
- ssh-agent(1): when adding PKCS#11-hosted private keys while specifying destination constraints, if the
PKCS#11 token returned multiple keys then only the first key had the constraints applied. Use of regular
private keys, FIDO tokens and unconstrained keys are unaffected. (CVE-2023-51384)
- ssh(1): if an invalid user or hostname that contained shell metacharacters was passed to ssh(1), and a
ProxyCommand, LocalCommand directive or match exec predicate referenced the user or hostname via %u, %h
or similar expansion token, then an attacker who could supply arbitrary user/hostnames to ssh(1) could
potentially perform command injection depending on what quoting was present in the user-supplied
ssh_config(5) directive. This situation could arise in the case of git submodules, where a repository
could contain a submodule with shell characters in its user/hostname. Git does not ban shell
metacharacters in user or host names when checking out repositories from untrusted sources. Although we
believe it is the user's responsibility to ensure validity of arguments passed to ssh(1), especially
across a security boundary such as the git example above, OpenSSH 9.6 now bans most shell metacharacters
from user and hostnames supplied via the command-line. This countermeasure is not guaranteed to be
effective in all situations, as it is infeasible for ssh(1) to universally filter shell metacharacters
potentially relevant to user-supplied commands. User/hostnames provided via ssh_config(5) are not subject
to these restrictions, allowing configurations that use strange names to continue to be used, under the
assumption that the user knows what they are doing in their own configuration files. (CVE-2023-51385)
Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version
number.
Javasolt megoldás
Upgrade to OpenSSH version 9.6 or later.
OpenSSH < 9.6 Multiple Vulnerabilities
The version of OpenSSH installed on the remote host is prior to 9.6. It is, therefore, affected by multiple
vulnerabilities as referenced in the release-9.6 advisory.
- ssh(1), sshd(8): implement protocol extensions to thwart the so-called Terrapin attack discovered by
Fabian Bumer, Marcus Brinkmann and Jrg Schwenk. This attack allows a MITM to effect a limited break of
the integrity of the early encrypted SSH transport protocol by sending extra messages prior to the
commencement of encryption, and deleting an equal number of consecutive messages immediately after
encryption starts. A peer SSH client/server would not be able to detect that messages were deleted. While
cryptographically novel, the security impact of this attack is fortunately very limited as it only allows
deletion of consecutive messages, and deleting most messages at this stage of the protocol prevents user
user authentication from proceeding and results in a stuck connection. The most serious identified impact
is that it lets a MITM to delete the SSH2_MSG_EXT_INFO message sent before authentication starts, allowing
the attacker to disable a subset of the keystroke timing obfuscation features introduced in OpenSSH 9.5.
There is no other discernable impact to session secrecy or session integrity. OpenSSH 9.6 addresses this
protocol weakness through a new strict KEX protocol extension that will be automatically enabled when
both the client and server support it. This extension makes two changes to the SSH transport protocol to
improve the integrity of the initial key exchange. Firstly, it requires endpoints to terminate the
connection if any unnecessary or unexpected message is received during key exchange (including messages
that were previously legal but not strictly required like SSH2_MSG_DEBUG). This removes most malleability
from the early protocol. Secondly, it resets the Message Authentication Code counter at the conclusion of
each key exchange, preventing previously inserted messages from being able to make persistent changes to
the sequence number across completion of a key exchange. Either of these changes should be sufficient to
thwart the Terrapin Attack. More details of these changes are in the PROTOCOL file in the OpenSSH source
distribition. (CVE-2023-48795)
- ssh-agent(1): when adding PKCS#11-hosted private keys while specifying destination constraints, if the
PKCS#11 token returned multiple keys then only the first key had the constraints applied. Use of regular
private keys, FIDO tokens and unconstrained keys are unaffected. (CVE-2023-51384)
- ssh(1): if an invalid user or hostname that contained shell metacharacters was passed to ssh(1), and a
ProxyCommand, LocalCommand directive or match exec predicate referenced the user or hostname via %u, %h
or similar expansion token, then an attacker who could supply arbitrary user/hostnames to ssh(1) could
potentially perform command injection depending on what quoting was present in the user-supplied
ssh_config(5) directive. This situation could arise in the case of git submodules, where a repository
could contain a submodule with shell characters in its user/hostname. Git does not ban shell
metacharacters in user or host names when checking out repositories from untrusted sources. Although we
believe it is the user's responsibility to ensure validity of arguments passed to ssh(1), especially
across a security boundary such as the git example above, OpenSSH 9.6 now bans most shell metacharacters
from user and hostnames supplied via the command-line. This countermeasure is not guaranteed to be
effective in all situations, as it is infeasible for ssh(1) to universally filter shell metacharacters
potentially relevant to user-supplied commands. User/hostnames provided via ssh_config(5) are not subject
to these restrictions, allowing configurations that use strange names to continue to be used, under the
assumption that the user knows what they are doing in their own configuration files. (CVE-2023-51385)
Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version
number.
Javasolt megoldás
Upgrade to OpenSSH version 9.6 or later.
OpenSSH < 9.6 Multiple Vulnerabilities
The version of OpenSSH installed on the remote host is prior to 9.6. It is, therefore, affected by multiple
vulnerabilities as referenced in the release-9.6 advisory.
- ssh(1), sshd(8): implement protocol extensions to thwart the so-called Terrapin attack discovered by
Fabian Bumer, Marcus Brinkmann and Jrg Schwenk. This attack allows a MITM to effect a limited break of
the integrity of the early encrypted SSH transport protocol by sending extra messages prior to the
commencement of encryption, and deleting an equal number of consecutive messages immediately after
encryption starts. A peer SSH client/server would not be able to detect that messages were deleted. While
cryptographically novel, the security impact of this attack is fortunately very limited as it only allows
deletion of consecutive messages, and deleting most messages at this stage of the protocol prevents user
user authentication from proceeding and results in a stuck connection. The most serious identified impact
is that it lets a MITM to delete the SSH2_MSG_EXT_INFO message sent before authentication starts, allowing
the attacker to disable a subset of the keystroke timing obfuscation features introduced in OpenSSH 9.5.
There is no other discernable impact to session secrecy or session integrity. OpenSSH 9.6 addresses this
protocol weakness through a new strict KEX protocol extension that will be automatically enabled when
both the client and server support it. This extension makes two changes to the SSH transport protocol to
improve the integrity of the initial key exchange. Firstly, it requires endpoints to terminate the
connection if any unnecessary or unexpected message is received during key exchange (including messages
that were previously legal but not strictly required like SSH2_MSG_DEBUG). This removes most malleability
from the early protocol. Secondly, it resets the Message Authentication Code counter at the conclusion of
each key exchange, preventing previously inserted messages from being able to make persistent changes to
the sequence number across completion of a key exchange. Either of these changes should be sufficient to
thwart the Terrapin Attack. More details of these changes are in the PROTOCOL file in the OpenSSH source
distribition. (CVE-2023-48795)
- ssh-agent(1): when adding PKCS#11-hosted private keys while specifying destination constraints, if the
PKCS#11 token returned multiple keys then only the first key had the constraints applied. Use of regular
private keys, FIDO tokens and unconstrained keys are unaffected. (CVE-2023-51384)
- ssh(1): if an invalid user or hostname that contained shell metacharacters was passed to ssh(1), and a
ProxyCommand, LocalCommand directive or match exec predicate referenced the user or hostname via %u, %h
or similar expansion token, then an attacker who could supply arbitrary user/hostnames to ssh(1) could
potentially perform command injection depending on what quoting was present in the user-supplied
ssh_config(5) directive. This situation could arise in the case of git submodules, where a repository
could contain a submodule with shell characters in its user/hostname. Git does not ban shell
metacharacters in user or host names when checking out repositories from untrusted sources. Although we
believe it is the user's responsibility to ensure validity of arguments passed to ssh(1), especially
across a security boundary such as the git example above, OpenSSH 9.6 now bans most shell metacharacters
from user and hostnames supplied via the command-line. This countermeasure is not guaranteed to be
effective in all situations, as it is infeasible for ssh(1) to universally filter shell metacharacters
potentially relevant to user-supplied commands. User/hostnames provided via ssh_config(5) are not subject
to these restrictions, allowing configurations that use strange names to continue to be used, under the
assumption that the user knows what they are doing in their own configuration files. (CVE-2023-51385)
Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version
number.
Javasolt megoldás
Upgrade to OpenSSH version 9.6 or later.
SSH Terrapin Prefix Truncation Weakness (CVE-2023-48795)
The remote SSH server is vulnerable to a man-in-the-middle prefix truncation weakness known as Terrapin. This can
allow a remote, man-in-the-middle attacker to bypass integrity checks and downgrade the connection's security.
Note that this plugin only checks for remote SSH servers that support either ChaCha20-Poly1305 or CBC with
Encrypt-then-MAC and do not support the strict key exchange countermeasures. It does not check for vulnerable software
versions.
Javasolt megoldás
Contact the vendor for an update with the strict key exchange countermeasures or disable the affected algorithms.
LOW (8)
ICMP Timestamp Request Remote Date Disclosure
The remote host answers to an ICMP timestamp request. This allows an
attacker to know the date that is set on the targeted machine, which
may assist an unauthenticated, remote attacker in defeating time-based
authentication protocols.
Timestamps returned from machines running Windows Vista / 7 / 2008 /
2008 R2 are deliberately incorrect, but usually within 1000 seconds of
the actual system time.
Javasolt megoldás
Filter out the ICMP timestamp requests (13), and the outgoing ICMP
timestamp replies (14).
SSL Certificate Chain Contains RSA Keys Less Than 2048 bits
Plugin ID: 69551
Port: tcp/25
At least one of the X.509 certificates sent by the remote host has a
key that is shorter than 2048 bits. According to industry standards
set by the Certification Authority/Browser (CA/B) Forum, certificates
issued after January 1, 2014 must be at least 2048 bits.
Some browser SSL implementations may reject keys less than 2048 bits
after January 1, 2014. Additionally, some SSL certificate vendors may
revoke certificates less than 2048 bits before January 1, 2014.
Note that Nessus will not flag root certificates with RSA keys less
than 2048 bits if they were issued prior to December 31, 2010, as the
standard considers them exempt.
Javasolt megoldás
Replace the certificate in the chain with the RSA key less than 2048
bits in length with a longer key, and reissue any certificates signed
by the old certificate.
SSL Certificate Chain Contains RSA Keys Less Than 2048 bits
Plugin ID: 69551
Port: tcp/443
At least one of the X.509 certificates sent by the remote host has a
key that is shorter than 2048 bits. According to industry standards
set by the Certification Authority/Browser (CA/B) Forum, certificates
issued after January 1, 2014 must be at least 2048 bits.
Some browser SSL implementations may reject keys less than 2048 bits
after January 1, 2014. Additionally, some SSL certificate vendors may
revoke certificates less than 2048 bits before January 1, 2014.
Note that Nessus will not flag root certificates with RSA keys less
than 2048 bits if they were issued prior to December 31, 2010, as the
standard considers them exempt.
Javasolt megoldás
Replace the certificate in the chain with the RSA key less than 2048
bits in length with a longer key, and reissue any certificates signed
by the old certificate.
SSL Certificate Chain Contains RSA Keys Less Than 2048 bits
Plugin ID: 69551
Port: tcp/465
At least one of the X.509 certificates sent by the remote host has a
key that is shorter than 2048 bits. According to industry standards
set by the Certification Authority/Browser (CA/B) Forum, certificates
issued after January 1, 2014 must be at least 2048 bits.
Some browser SSL implementations may reject keys less than 2048 bits
after January 1, 2014. Additionally, some SSL certificate vendors may
revoke certificates less than 2048 bits before January 1, 2014.
Note that Nessus will not flag root certificates with RSA keys less
than 2048 bits if they were issued prior to December 31, 2010, as the
standard considers them exempt.
Javasolt megoldás
Replace the certificate in the chain with the RSA key less than 2048
bits in length with a longer key, and reissue any certificates signed
by the old certificate.
SSL Certificate Chain Contains RSA Keys Less Than 2048 bits
Plugin ID: 69551
Port: tcp/993
At least one of the X.509 certificates sent by the remote host has a
key that is shorter than 2048 bits. According to industry standards
set by the Certification Authority/Browser (CA/B) Forum, certificates
issued after January 1, 2014 must be at least 2048 bits.
Some browser SSL implementations may reject keys less than 2048 bits
after January 1, 2014. Additionally, some SSL certificate vendors may
revoke certificates less than 2048 bits before January 1, 2014.
Note that Nessus will not flag root certificates with RSA keys less
than 2048 bits if they were issued prior to December 31, 2010, as the
standard considers them exempt.
Javasolt megoldás
Replace the certificate in the chain with the RSA key less than 2048
bits in length with a longer key, and reissue any certificates signed
by the old certificate.
OpenSSH < 10.0 DisableForwarding
The version of OpenSSH installed on the remote host is prior to 10.0. It is, therefore, affected by a
vulnerability. In sshd in OpenSSH the DisableForwarding directive does not adhere to the documentation stating that it
disables X11 and agent forwarding.
Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version
number.
Javasolt megoldás
Upgrade to OpenSSH version 10.0 or later.
OpenSSH < 10.1 / 10.1p1 Multiple Vulnerabilities
The version of OpenSSH installed on the remote host is prior to 10.1. It is, therefore, affected by multiple
vulnerabilities:
- ssh in OpenSSH before 10.1 allows control characters in usernames that originate from certain possibly
untrusted sources, potentially leading to code execution when a ProxyCommand is used. The untrusted
sources are the command line and %-sequence expansion of a configuration file. (A configuration file
that provides a complete literal username is not categorized as an untrusted source.) (CVE-2025-61984)
- ssh in OpenSSH before 10.1 allows the '\0' character in an ssh:// URI, potentially leading to code execution when a
ProxyCommand is used. (CVE-2025-61985)
Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version
number.
Javasolt megoldás
Upgrade to OpenSSH version 10.1/10.1p1 or later.
OpenSSH < 10.1 / 10.1p1 Multiple Vulnerabilities
The version of OpenSSH installed on the remote host is prior to 10.1. It is, therefore, affected by multiple
vulnerabilities:
- ssh in OpenSSH before 10.1 allows control characters in usernames that originate from certain possibly
untrusted sources, potentially leading to code execution when a ProxyCommand is used. The untrusted
sources are the command line and %-sequence expansion of a configuration file. (A configuration file
that provides a complete literal username is not categorized as an untrusted source.) (CVE-2025-61984)
- ssh in OpenSSH before 10.1 allows the '\0' character in an ssh:// URI, potentially leading to code execution when a
ProxyCommand is used. (CVE-2025-61985)
Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version
number.
Javasolt megoldás
Upgrade to OpenSSH version 10.1/10.1p1 or later.