CVE-2020-24606 Explained : Impact and Mitigation
Learn about CVE-2020-24606, a vulnerability in Squid before 4.13 and 5.x before 5.0.4 allowing a trusted peer to perform Denial of Service by consuming all CPU cycles. Find out the impact, affected systems, exploitation mechanism, and mitigation steps.
Squid before 4.13 and 5.x before 5.0.4 allows a trusted peer to perform Denial of Service by consuming all available CPU cycles during handling of a crafted Cache Digest response message. Learn about the impact, technical details, and mitigation steps for this vulnerability.
Understanding CVE-2020-24606
This CVE involves a vulnerability in Squid versions before 4.13 and 5.x before 5.0.4 that can lead to a Denial of Service attack.
What is CVE-2020-24606?
Squid versions prior to 4.13 and 5.x before 5.0.4 are susceptible to a trusted peer causing a Denial of Service by utilizing all CPU cycles when processing a specially crafted Cache Digest response message.
The Impact of CVE-2020-24606
The vulnerability allows a trusted peer to exhaust CPU resources, leading to a Denial of Service condition. This occurs specifically when cache_peer is used with the cache digests feature due to mishandling of EOF in peerDigestHandleReply() livelocking.
Technical Details of CVE-2020-24606
This section provides more in-depth technical insights into the CVE.
Vulnerability Description
The issue arises from a livelocking problem in peer_digest.cc, where a trusted peer can exploit the cache digests feature to consume all CPU cycles, causing a DoS condition.
Affected Systems and Versions
- Squid versions before 4.13
- Squid 5.x versions before 5.0.4
Exploitation Mechanism
The vulnerability can be exploited by a trusted peer sending a specially crafted Cache Digest response message, triggering the excessive consumption of CPU cycles.
Mitigation and Prevention
Protect your systems from CVE-2020-24606 with these mitigation strategies.
Immediate Steps to Take
- Update Squid to version 4.13 or 5.0.4, which contain patches addressing this vulnerability.
- Disable the cache digests feature if not essential for your setup.
Long-Term Security Practices
- Regularly monitor and update your Squid installations to stay protected against known vulnerabilities.
- Implement network segmentation to limit the impact of potential DoS attacks.
Patching and Updates
- Apply security patches promptly to ensure your Squid instances are protected against the CVE-2020-24606 vulnerability.