Ssh-2.0-cisco-1.25 — Vulnerability

An unpatched instance broadcasting the SSH-2.0-Cisco-1.25 profile may be vulnerable to several critical flaws in Cisco's SSH state machines and protocol engines: 1. Authentication Bypass (CVE-2015-6280)

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

When an SSH client connects to a server, the server sends a "banner" identifying its software version. In this case, the string breaks down as follows:

In the world of network security, few things cause a spike in adrenaline quite like an unfamiliar banner appearing in your vulnerability scanner. For many system administrators and security analysts, the string is one such trigger. Scrolling through a Nessus, OpenVAS, or Qualys report, this identifier often appears under "SSH Server Version Information," flagged with a medium or high-severity warning. ssh-2.0-cisco-1.25 vulnerability

Understanding the implications of this banner, the actual historical and modern vulnerabilities associated with it, and mitigation strategies ensures robust infrastructure defense. Understanding the SSH-2.0-Cisco-1.25 Banner

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If you have recently run a vulnerability scan like Nessus or OpenVAS against your Cisco infrastructure, you may have seen a reference to . While this string is actually a version banner rather than a single specific "vulnerability," it often serves as a primary indicator for several critical security flaws affecting Cisco’s SSH implementation. What is SSH-2.0-Cisco-1.25? An unpatched instance broadcasting the SSH-2

Vulnerable releases include many 12.2, 12.3, 12.4 trains. Fixed releases are typically 12.4(24)T5 or higher, 12.2(33)SXI5, 15.1(1)T1, etc. Check for exact fixed versions.

: The device is utilizing version 1.25 of Cisco’s internal code package for handling secure shell connections.

Router(config)# no banner login Router(config)# no banner motd Use code with caution. Summary of Best Practices Action Item Technical Impact Patches core software flaws Enforce SSH v2 Eliminates weak SSH v1 protocol Apply VTY ACLs Blocks unauthorized IPs from connecting Disable Weak Ciphers Prevents cryptographic downgrades Censys: Over 103,000 instances identified

Use Access Control Lists (ACLs) to limit SSH access to known, trusted management IP addresses.

If you cannot upgrade immediately, harden the existing SSH configuration to minimize attack surfaces. Run the following commands in global configuration mode: Router(config)# ip ssh version 2 Use code with caution. Set Strict Timeouts and Authentication Limits:

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.

Upgrade to a fixed IOS version:

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 SSH Terrapin Prefix Truncation Weakness - Cisco Community