The SSH-2.0-Cisco-1.25 vulnerability is a serious security flaw that can allow an attacker to gain unauthorized access to Cisco devices. It is essential to take immediate action to mitigate and remediate this vulnerability to prevent potential exploitation.
: An attacker can establish a standard SSH session and transmit a carefully crafted sequence of malformed packets. Instead of dropping the corrupted packets, the engine triggers an unexpected internal error, causing the entire device to reload or crash, leading to a network-wide Denial of Service. 3. Cryptographic Downgrade and Terrapin Attacks
[Detect Banner] -> [Verify Software with Cisco Checker] -> [Apply ACLs] -> [Deploy Software Update] Step 1: Query the Internal Firmware Version ssh-2.0-cisco-1.25 vulnerability
SSH0: Exchanging versions - SSH-2.0-Cisco-1.25 SSH0: send SSH message: outdated is NULL server version string: SSH-2.0-Cisco-1.25
0 Helpful. Georg Pauwen. VIP Alumni. 02-16-2021 12:30 AM. Hello, I think the '1.25' part is the Cisco specific vendor version ID. Cisco Community The SSH-2
If encryption is weakened, attackers might be able to hijack administrative sessions.
: The attack forces a downgrade of the connection's security profile , turning off extensions like ChaCha20-Poly1305 or Encrypt-then-MAC, leaving the active session exposed to data decryption or session hijacking. Cryptographic Degradation (Diffie-Hellman Group 1 & MD5) Instead of dropping the corrupted packets, the engine
! Example Access Control List access-list 10 permit 192.168.10.5 line vty 0 4 access-class 10 in transport input ssh Use code with caution. Conclusion
! Example Configuration Hardening ip ssh server algorithm encryption aes128-ctr aes192-ctr aes256-ctr ip ssh server algorithm mac hmac-sha2-256 hmac-sha2-512 ip ssh server algorithm kex diffie-hellman-group14-sha256 Use code with caution. 4. Implement Strict Access Control