GPEN · Question #448
A customer has asked for a scan or vulnerable SSH servers. What is the penetration tester attempting to accomplish using the following Nmap command?
The correct answer is D. Checking protocol version. Nmap's version detection flag (-sV) can fingerprint SSH daemons to reveal the protocol version, helping testers identify servers running deprecated or vulnerable SSH versions.
Question
A customer has asked for a scan or vulnerable SSH servers. What is the penetration tester attempting to accomplish using the following Nmap command?
Options
- AChecking operating system version
- BRunning an exploit against the target
- CChecking configuration
- DChecking protocol version
How the community answered
(29 responses)- A21% (6)
- B7% (2)
- C3% (1)
- D69% (20)
Why each option
Nmap's version detection flag (-sV) can fingerprint SSH daemons to reveal the protocol version, helping testers identify servers running deprecated or vulnerable SSH versions.
OS version detection requires Nmap's -O flag and relies on TCP/IP stack fingerprinting, which is a separate operation from identifying the SSH service version on a specific port.
Nmap is a scanning and enumeration tool - it does not execute exploits against targets; exploit delivery against SSH would require a framework like Metasploit.
Checking SSH configuration details such as supported ciphers and key exchange algorithms requires dedicated tools like ssh-audit or Nmap NSE scripts such as ssh2-enum-algos, not a standard version scan.
When scanning for vulnerable SSH servers, Nmap with the -sV flag probes the SSH port and reads the protocol banner, revealing both the SSH protocol version (SSH-1 vs SSH-2) and the daemon version (e.g., OpenSSH 5.x). SSH protocol version 1 is cryptographically weak and its presence indicates a vulnerable configuration, making this version check the primary objective of the command shown.
Concept tested: Nmap SSH protocol version detection scanning
Source: https://nmap.org/book/man-version-detection.html
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