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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.

Vulnerability Discovery & Scanning

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)
  • A
    21% (6)
  • B
    7% (2)
  • C
    3% (1)
  • D
    69% (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.

AChecking operating system version

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.

BRunning an exploit against the target

Nmap is a scanning and enumeration tool - it does not execute exploits against targets; exploit delivery against SSH would require a framework like Metasploit.

CChecking configuration

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.

DChecking protocol versionCorrect

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

Topics

#Nmap#SSH scanning#protocol version#service detection

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