! Set timeouts and authentication limits ip ssh time-out 60 ip ssh authentication-retries 2
Organizations should implement continuous monitoring for suspicious SSH traffic. This includes detection of brute-force attempts, unusual numbers of authentication failures, unexpected cryptographic negotiations, and anomalous connection patterns from unauthorized source IP addresses. SIEM integration and network traffic analysis tools can help identify early signs of compromise.
# Disable weak Diffie-Hellman groups ip ssh dh min size 2048 # Specify secure ciphers (prefer CTR or GCM modes) ip ssh server algorithm encryption aes256-ctr aes192-ctr aes128-ctr # Specify secure Message Authentication Codes (MACs) ip ssh server algorithm mac hmac-sha2-256 hmac-sha2-512 Use code with caution. Copied to clipboard Step 3: Obfuscate the Banner (Optional) ssh-2.0-cisco-1.25 vulnerability
The SSH-2.0-Cisco-1.25 vulnerability is a weakness in the Cisco SSH implementation that allows an attacker to exploit the server's authentication mechanism. Specifically, the vulnerability occurs when the server is configured to use a specific type of authentication, known as "keyboard-interactive" authentication.
Security research reports from April 2025 highlighted significant global exposure for devices identifying as "SSH-2.0-Cisco-1.25". Approximately 92,000 exposed instances found. Censys: Over 103,000 instances identified. FOFA: Up to 309,000 instances detected. Related Historical Vulnerabilities SIEM integration and network traffic analysis tools can
Certain historic deployments of Cisco-1.25 lack strict cryptographic path validation when utilizing RSA keys for administrator access.
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 Specifically, the vulnerability occurs when the server is
Two things made the difference: quick containment and a tested patch plan. Because Rosa prioritized limiting access first, even if an exploit existed, attackers had far fewer opportunities. Because she tested upgrades in a lab, the hospital avoided a surprise outage.
⚠️ is widely exploited in 1.25 today, but DoS and downgrade attacks are still possible.
: Continued use of CBC-mode ciphers (e.g., aes128-cbc ), which are susceptible to side-channel attacks. How to Secure Your Cisco Device
1. Authentication Bypass via RSA Public Key Flaw (CVE-2015-0235 / Similar)