New! — Ssh20cisco125 Vulnerability

Understanding the Vulnerability

The "ssh20cisco125" vulnerability refers to a specific security flaw affecting the Secure Shell (SSH) implementation in various Cisco networking products. Identified primarily by its protocol banner— SSH-2.0-Cisco-1.25 —the vulnerability is formally tracked as CVE-2022-20864 .

The SSH-2-Cisco-125 vulnerability affects specific Cisco devices, including: ssh20cisco125 vulnerability

3. Upgrade and Reload

Scenario B: Active Man-in-the-Middle

1. Scan for port 22 (SSH) on Cisco devices.
2. Probe the SSH handshake to extract the host key modulus during the SSH_MSG_KEXINIT exchange.
3. Extract the 125-byte modulus from the server’s public key.
4. Factor the modulus using tools like yafu, CADO-NFS, or Msieve (typically 2-6 hours on a modern multi-core server).
5. Recompute the private key.
6. Decrypt previously captured SSH sessions or perform live MITM attacks.

Backup and recovery

• Limit SSH access to a small set of management IPs using ACLs or firewall rules.
• Put devices behind a management VLAN or out-of-band management network.