CVE-2018-20969 : Exploit Details and Defense Strategies

This CVE-2018-20969 article provides insights into a vulnerability in GNU patch up to version 2.7.6 that allows the usage of strings starting with a "!" character.

Understanding CVE-2018-20969

The vulnerability identified in the CVE-2018-20969 commit relates to the pch.c file in GNU patch and its handling of strings starting with a "!" character.

What is CVE-2018-20969?

The issue in GNU patch allows the use of strings starting with a "!" character, specifically related to the syntax used in the ed program, unrelated to shell metacharacters.

The Impact of CVE-2018-20969

The vulnerability could potentially lead to command injection or directory traversal attacks, compromising system integrity and security.

Technical Details of CVE-2018-20969

The technical aspects of the CVE-2018-20969 vulnerability are as follows:

Vulnerability Description

The do_ed_script function in pch.c in GNU patch through 2.7.6 does not block strings beginning with a "!" character, allowing potential exploitation.

Affected Systems and Versions

Product: GNU patch
Vendor: GNU
Versions affected: Up to version 2.7.6

Exploitation Mechanism

The vulnerability allows attackers to inject malicious commands or traverse directories by utilizing strings starting with a "!" character.

Mitigation and Prevention

To address CVE-2018-20969, consider the following mitigation strategies:

Immediate Steps to Take

Update GNU patch to version 2.7.7 or later to patch the vulnerability.
Monitor and restrict user input that may contain strings starting with a "!" character.

Long-Term Security Practices

Implement input validation mechanisms to sanitize user inputs effectively.
Regularly update software and apply security patches to prevent known vulnerabilities.

Patching and Updates

Stay informed about security advisories and updates from GNU and other relevant vendors.
Apply patches promptly to ensure system security and integrity.