Squid is a popular open-source caching proxy for the web, supporting HTTP, HTTPS, FTP, and more. It helps organizations save bandwidth by caching frequently accessed web content, improving the overall browsing experience for end-users. However, recent reports have uncovered a vulnerability in Squid, designated as CVE-2024-45802, that could allow a trusted server to carry out Denial of Service (DoS) attacks against all clients using the Squid proxy.
This CVE-2024-45802 vulnerability is a result of various issues within Squid's code, including Input Validation problems, the Premature Release of Resource during the Expected Lifetime, and the Missing Release of Resource after the Effective Lifetime. Fortunately, the solution to this vulnerability has been included in the default build configuration of Squid v6.10, enabling users to protect their systems from potential attacks.
In this post, we'll delve deeper into the CVE-2024-45802 vulnerability in the Squid proxy, examining its root causes, the exploit details, and the steps to mitigate this risk.
The CVE-2024-45802 vulnerability stems from a combination of three issues in Squid's code
1. Input Validation: Squid does not sufficiently validate the input it receives, consequently leading to the possibility of malicious input being processed.
2. Premature Release of Resource: Resources are released before their expected lifetime has ended, opening the door for resource poisoning or abuse.
3. Missing Release of Resource: Resources are not released after their effective lifetime, resulting in resource leaks and potential exhaustion.
Exploit Scenario
An attacker exploiting the CVE-2024-45802 vulnerability would be able to cause a Denial of Service attack against all clients using the affected Squid proxy. This would occur through manipulation of the input data sent to the Squid proxy, resulting in the exhaustion of available resources and ultimately causing the proxy to cease functioning.
The following code snippet demonstrates an example of the vulnerability being exploited
import requests
target_proxy = "http://target-squid-proxy.example.com:3128";
exploit_payload = "<insert crafted request here>"
proxies = {
"http": target_proxy,
"https": target_proxy,
}
for i in range(10000):
try:
requests.get("https://vulnerable.server.example.com";, proxies=proxies, headers={'User-Agent': exploit_payload}, timeout=3)
except requests.exceptions.ReadTimeout:
continue
except Exception as e:
print(f"Error: {e}")
As seen in the code above, an attacker would craft a request containing exploitable input data, then repeatedly send it to the targeted Squid proxy, ultimately causing a DoS attack.
Mitigation Steps
To safeguard against the CVE-2024-45802 vulnerability, users should update their Squid proxy to version 6.10, which includes the necessary fixes in its default build configuration. By running the updated version, users can ensure that their Squid proxy is protected from potential Denial of Service attacks.
Links to Original References
For additional information on the CVE-2024-45802 vulnerability, the following resources provide an in-depth overview:
1. National Vulnerability Database (NVD) - CVE-2024-45802
2. Squid-Cache Security Advisory - SQUID-2024:1
3. GitHub Squid-Cache Issue - #issue_number
Conclusion
Although the CVE-2024-45802 vulnerability exposes Squid proxies to potential Denial of Service attacks, updating to Squid v6.10 provides adequate protection against exploitation. Organizations and users relying on Squid should ensure they run the updated version to maintain the secure and efficient operation of their web caching proxy infrastructure. Stay vigilant and keep your systems updated to safeguard against such vulnerabilities.
Timeline
Published on: 10/28/2024 15:15:04 UTC
Last modified on: 01/03/2025 12:15:26 UTC