CVE-2020-8631 Explained : Impact and Mitigation

Cloud-init through version 19.4 has a vulnerability that relies on Mersenne Twister for generating random passwords, making it easier for attackers to predict passwords.

Understanding CVE-2020-8631

This CVE involves a weakness in the password generation process in cloud-init, potentially exposing systems to password prediction attacks.

What is CVE-2020-8631?

Cloud-init through version 19.4 uses the Mersenne Twister algorithm for password generation, which can be exploited by attackers to predict passwords due to the predictable nature of the random number generation.

The Impact of CVE-2020-8631

The vulnerability in cloud-init can lead to compromised system security as attackers may exploit the predictable password generation to gain unauthorized access.

Technical Details of CVE-2020-8631

Cloud-init vulnerability details and affected systems.

Vulnerability Description

The issue stems from the use of Mersenne Twister in cloud-init's password generation process, allowing attackers to predict passwords easily.

Affected Systems and Versions

Cloud-init versions up to 19.4 are affected by this vulnerability.

Exploitation Mechanism

The vulnerability arises from the rand_str function in cloudinit/util.py, which uses the random.choice function with Mersenne Twister, enabling password prediction.

Mitigation and Prevention

Steps to mitigate the CVE-2020-8631 vulnerability.

Immediate Steps to Take

Update cloud-init to a version beyond 19.4 to patch the vulnerability.
Implement strong password policies to mitigate the risk of password prediction attacks.

Long-Term Security Practices

Consider using cryptographically secure random number generators for password generation.
Regularly review and update password generation mechanisms to align with best security practices.

Patching and Updates

Stay informed about security updates for cloud-init and promptly apply patches to address known vulnerabilities.