ssh-diffie-hellman-logjam: SSH Diffie-Hellman Modulus <= 1024 Bits

2025-08-01 SSH Diffie-Hellman PoC Public

Description

SSH weak algorithms are outdated cryptographic methods that pose security risks. Identifying and disabling these vulnerable algorithms is crucial for enhancing the overall security of SSH connections.

PoC

id: ssh-diffie-hellman-logjam

info:
  name: SSH Diffie-Hellman Modulus <= 1024 Bits
  author: pussycat0x
  severity: low
  description: |
    SSH weak algorithms are outdated cryptographic methods that pose security risks. Identifying and disabling these vulnerable algorithms is crucial for enhancing the overall security of SSH connections.
  reference:
    - https://access.redhat.com/solutions/4278651
  metadata:
    verified: true
    max-request: 2
    shodan-query: product:"OpenSSH"
  tags: js,enum,ssh,misconfig,network,discovery

javascript:
  - pre-condition: |
      isPortOpen(Host,Port);
    code: |
      let m = require("nuclei/ssh");
      let c = m.SSHClient();
      let response = c.ConnectSSHInfoMode(Host, Port);
      Export(response);

    args:
      Host: "{{Host}}"
      Port: "22"

    matchers-condition: and
    matchers:
      - type: word
        words:
          - "kex_algorithms"

      - type: word
        words:
          - "diffie-hellman-group1-sha1"
# digest: 4a0a004730450221008c2b3ad82250708df0d62a7258c96d484018bfc5493b1a52bd927292b45681120220617fe8d66ee1496c9b69f960cf439195fb6ad2c9d1b6ece288724fd08ec9e69a:922c64590222798bb761d5b6d8e72950

# Visit https://trap.biu.life/ to view exploit trends for this vulnerability.

References