OpenSSH < 7.3 Multiple Vulnerabilities
High Nessus Plugin ID 93194
SynopsisThe SSH server running on the remote host is affected by multiple vulnerabilities.
DescriptionAccording to its banner, the version of OpenSSH running on the remote host is prior to 7.3. It is, therefore, affected by multiple vulnerabilities :
- A local privilege escalation when the UseLogin feature is enabled and PAM is configured to read .pam_environment files from home directories. (CVE-2015-8325)
- A flaw exists that is due to the program returning shorter response times for authentication requests with overly long passwords for invalid users than for valid users. This may allow a remote attacker to conduct a timing attack and enumerate valid usernames.
- A denial of service vulnerability exists in the auth_password() function in auth-passwd.c due to a failure to limit password lengths for password authentication. An unauthenticated, remote attacker can exploit this, via a long string, to consume excessive CPU resources, resulting in a denial of service condition. (CVE-2016-6515)
- An unspecified flaw exists in the CBC padding oracle countermeasures that allows an unauthenticated, remote attacker to conduct a timing attack.
- A flaw exists due to improper operation ordering of MAC verification for Encrypt-then-MAC (EtM) mode transport MAC algorithms when verifying the MAC before decrypting any ciphertext. An unauthenticated, remote attacker can exploit this, via a timing attack, to disclose sensitive information.
Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.
SolutionUpgrade to OpenSSH version 7.3 or later.