CVE-2019-15796 Explained : Impact and Mitigation

Python-apt downloads from untrusted sources.

Understanding CVE-2019-15796

In versions 1.9.3ubuntu2 and earlier, Python-apt did not verify signed hashes in certain functions, allowing downloads from unsigned repositories, posing a security risk. This vulnerability has been fixed in later versions.

What is CVE-2019-15796?

Python-apt versions prior to 1.9.5 did not enforce signed hashes in critical functions, enabling downloads from untrusted sources.

The Impact of CVE-2019-15796

The vulnerability allowed malicious actors to download packages from unsigned repositories, potentially leading to the installation of compromised software.

Technical Details of CVE-2019-15796

Vulnerability Description

Python-apt versions before 1.9.5 lacked proper checks for signed hashes, enabling downloads from untrusted sources.

Affected Systems and Versions

Python-apt versions 0.8.3ubuntu7.5, 0.9.3.5ubuntu3+esm2, 1.1.0~beta1ubuntu0.16.04.7, 1.6.5ubuntu0.1, 1.9.0ubuntu1.2, and 1.9.5 were affected.

Exploitation Mechanism

The lack of hash signing verification in specific functions allowed attackers to download packages from repositories without proper validation.

Mitigation and Prevention

Immediate Steps to Take

Upgrade Python-apt to version 1.9.5 or later to mitigate the vulnerability.
Avoid downloading packages from untrusted repositories.

Long-Term Security Practices

Regularly update software to the latest versions to patch known vulnerabilities.
Implement secure coding practices to prevent similar issues in the future.

Patching and Updates

Apply patches provided by Canonical to address the security flaw in Python-apt.