CVE-2019-11251 Explained : Impact and Mitigation

Kubernetes kubectl cp command vulnerability allowing symlink directory traversal.

Understanding CVE-2019-11251

A vulnerability in Kubernetes versions 1.1-1.12 and prior to 1.13.11, 1.14.7, and 1.15.4 in the kubectl cp command.

What is CVE-2019-11251?

In versions 1.1-1.12 of Kubernetes, as well as versions prior to 1.13.11, 1.14.7, and 1.15.4, a vulnerability in the kubectl cp command allows an attacker to place a file outside the intended destination directory by exploiting symlinks.

The Impact of CVE-2019-11251

Attack Complexity: High
Attack Vector: Network
Base Score: 4.8 (Medium)
Integrity Impact: High
Privileges Required: Low
User Interaction: Required

Technical Details of CVE-2019-11251

Affects Kubernetes versions 1.1-1.12 and prior to 1.13.11, 1.14.7, and 1.15.4.

Vulnerability Description

Attacker uses two symlinks from a malicious container's tar output to place a file outside the intended directory.

Affected Systems and Versions

Kubernetes versions prior to 1.13.11, 1.14.7, and 1.15.4, as well as versions 1.1-1.12.

Exploitation Mechanism

Attacker exploits the kubectl cp command vulnerability to place a file outside the specified destination directory.

Mitigation and Prevention

Immediate Steps to Take:

Update Kubernetes to versions 1.13.11, 1.14.7, or 1.15.4.
Avoid using the kubectl cp command in untrusted environments. Long-Term Security Practices:
Regularly monitor and update Kubernetes for security patches.
Implement least privilege access controls.
Educate users on secure container practices.
Conduct security audits and penetration testing.
Stay informed about security advisories and best practices.

Patching and Updates

Apply security releases of kubectl versions v1.16.0, 1.15.4, 1.14.7, and 1.13.11.