CVE-2019-9639 : Exploit Details and Defense Strategies

A problem was found in the EXIF component of PHP versions prior to 7.1.27, 7.2.x before 7.2.16, and 7.3.x before 7.3.3. An uninitialized read occurs in the exif_process_IFD_in_MAKERNOTE function due to mishandling of the data_len variable.

Understanding CVE-2019-9639

What is CVE-2019-9639?

CVE-2019-9639 is a vulnerability in the EXIF component of PHP versions before 7.1.27, 7.2.x before 7.2.16, and 7.3.x before 7.3.3, leading to an uninitialized read in a specific function.

The Impact of CVE-2019-9639

This vulnerability could allow an attacker to exploit the uninitialized read issue in the PHP EXIF component, potentially leading to information disclosure or further attacks.

Technical Details of CVE-2019-9639

Vulnerability Description

The vulnerability stems from mishandling the data_len variable in the exif_process_IFD_in_MAKERNOTE function in PHP versions prior to 7.1.27, 7.2.x before 7.2.16, and 7.3.x before 7.3.3.

Affected Systems and Versions

PHP versions before 7.1.27
PHP 7.2.x before 7.2.16
PHP 7.3.x before 7.3.3

Exploitation Mechanism

The vulnerability allows for an uninitialized read in a specific PHP function, potentially enabling attackers to access sensitive information.

Mitigation and Prevention

Immediate Steps to Take

Update PHP to versions 7.1.27, 7.2.16, or 7.3.3 or later to mitigate the vulnerability.
Monitor official security advisories for patches and updates.

Long-Term Security Practices

Regularly update PHP and other software components to the latest secure versions.
Implement secure coding practices to prevent similar vulnerabilities.

Patching and Updates

Apply patches provided by PHP to address the uninitialized read vulnerability in the EXIF component.