Copssh version 5.3.0 bundle contains 32/64-bit client/server installers with OpenSSH 7.0. Focus of this release is primarily to deprecate weak, legacy and/or unsafe cryptography:
- Support for the legacy SSH version 1 protocol is disabled by default at compile time.
- Support for the 1024-bit diffie-hellman-group1-sha1 key exchange is disabled by default at run-time. It may be re-enabled using the instructions at http://www.openssh.com/legacy.html
- Support for ssh-dss, ssh-dss-cert-* host and user keys is disabled by default at run-time. These may be re-enabled using the instructions at http://www.openssh.com/legacy.html
- Support for the legacy v00 cert format has been removed.
Security related fixes:
- sshd(8): OpenSSH 6.8 and 6.9 incorrectly set TTYs to be world-writable. Local attackers may be able to write arbitrary messages to logged-in users, including terminal escape sequences. Reported by Nikolay Edigaryev.
- sshd(8): Portable OpenSSH only: Fixed a privilege separation weakness related to PAM support. Attackers who could successfully compromise the pre-authentication process for remote code execution and who had valid credentials on the host could impersonate other users. Reported by Moritz Jodeit.
- sshd(8): Portable OpenSSH only: Fixed a use-after-free bug related to PAM support that was reachable by attackers who could compromise the pre-authentication process for remote code execution. Also reported by Moritz Jodeit.
- sshd(8): fix circumvention of MaxAuthTries using keyboard-interactive authentication. By specifying a long, repeating keyboard-interactive "devices" string, an attacker could request the same authentication method be tried thousands of times in a single pass. The LoginGraceTime timeout in sshd(8) and any authentication failure delays implemented by the authentication mechanism itself were still applied. Found by Kingcope.
