CVE-2019-11044 : Exploit Details and Defense Strategies

PHP link() function vulnerability on Windows

Understanding CVE-2019-11044

What is CVE-2019-11044?

In PHP versions 7.2.x below 7.2.26, 7.3.x below 7.3.13, and 7.4.0 on Windows, the PHP link() function has a security vulnerability. It mishandles filenames with an embedded \0 byte, potentially leading to security risks, especially in applications that validate paths.

The Impact of CVE-2019-11044

The vulnerability allows attackers to manipulate filenames, posing security risks in path verification processes.

Technical Details of CVE-2019-11044

Vulnerability Description

The PHP link() function on Windows incorrectly processes filenames with embedded \0 bytes, which can be exploited by attackers.

Affected Systems and Versions

Platforms: Windows
PHP Versions: 7.2.x (<7.2.26), 7.3.x (<7.3.13), 7.4.x (<7.4.1)

Exploitation Mechanism

Attackers can use filenames with embedded \0 bytes to bypass path verification, potentially accessing unauthorized areas.

Mitigation and Prevention

Immediate Steps to Take

Update PHP to versions 7.2.26, 7.3.13, or 7.4.1 to mitigate the vulnerability.
Review and restrict access permissions to sensitive directories.

Long-Term Security Practices

Regularly monitor and update PHP versions to address security flaws.
Implement input validation to prevent malicious filenames.
Conduct security audits to identify and remediate vulnerabilities.

Patching and Updates

Apply patches provided by PHP Group to fix the link() function vulnerability.