Skip to main content

Unrestricted access between network segments - StrictHostKeyChecking

Description

The JSch StrictHostKeyChecking configuration is set to no, this indicates that connections may be made to unknown servers or servers that have changed their keys, generating new ones and adding them by default to the known server files.

Impact

  • Start connections to untrusted servers.
  • Increase the possibility of attacks such as MitM and spoofing.
  • Receive or send malicious data or files.
  • Leak sensitive information such as users and passwords.

Recommendation

  • Limit access to administrative services such as SSH.
  • Implement safe values for StricktHostKeyChecking configuration.

Threat

Anonymous attacker from the Internet.

Expected Remediation Time

⌚ 15 minutes.

Score

Default score using CVSS 3.1. It may change depending on the context of the vulnerability.

Base

  • Attack vector: N
  • Attack complexity: H
  • Privileges required: N
  • User interaction: N
  • Scope: U
  • Confidentiality: L
  • Integrity: L
  • Availability: N

Temporal

  • Exploit code madurity: P
  • Remediation level: O
  • Report confidence: X

Result

  • Vector string: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N/E:P/RL:O/RC:X
  • Score:
    • Base: 4.8
    • Temporal: 4.3
  • Severity:
    • Base: Medium
    • Temporal: Medium

Code Examples

Compliant code

The application enables Strict Host Key Checking

java.util.Properties config = new java.util.Properties();
config.put("StrictHostKeyChecking", "yes");
session.setConfig(config);

Non compliant code

The application does not enable Strict Host Key Checking

java.util.Properties config = new java.util.Properties();
config.put("StrictHostKeyChecking", "no");
session.setConfig(config);

Requirements