CVE-2021-3761 Explained : Impact and Mitigation

A vulnerability has been discovered in OctoRPKI, a product developed by Cloudflare, that allows a CA issuer in the RPKI to manipulate VRP values, potentially impacting BGP routing.

Understanding CVE-2021-3761

This CVE highlights a security issue in OctoRPKI that could be exploited by attackers to disable RPKI Origin Validation in a victim network.

What is CVE-2021-3761?

The vulnerability in OctoRPKI prior to version 1.3.0 allows a CA issuer to emit an invalid VRP "MaxLength" value, leading to RTR session termination and potential BGP hijacking attempts.

The Impact of CVE-2021-3761

Attackers can exploit this vulnerability to disable RPKI Origin Validation in target networks, such as AS 13335 (Cloudflare), before launching BGP hijacks that could lead to availability issues.

Technical Details of CVE-2021-3761

This section delves into the specifics of the vulnerability within OctoRPKI.

Vulnerability Description

The issue arises due to a contextual out-of-bounds check missing in OctoRPKI, allowing malicious manipulation of VRP values.

Affected Systems and Versions

OctoRPKI versions prior to 1.3.0 are vulnerable to this issue, leaving networks at risk of RTR session termination and BGP routing churn.

Exploitation Mechanism

By tricking OctoRPKI into emitting an invalid VRP value, attackers can disrupt RPKI Origin Validation and potentially launch BGP hijacking attacks.

Mitigation and Prevention

To address CVE-2021-3761, proactive security measures and updates are essential.

Immediate Steps to Take

Organizations using OctoRPKI should upgrade to version 1.3.0 to prevent exploitation of this vulnerability.

Long-Term Security Practices

Regularly monitor RPKI implementations and verify the integrity of BGP routing to detect and mitigate potential threats.

Patching and Updates

Cloudflare has released version 1.3.0 as a solution to this vulnerability. It is crucial for affected users to apply this patch promptly to secure their networks.