CVE-2013-0189 in Squid
Summary
by MITRE
cachemgr.cgi in Squid 3.1.x and 3.2.x, possibly 3.1.22, 3.2.4, and other versions, allows remote attackers to cause a denial of service (resource consumption) via a crafted request. NOTE: this issue is due to an incorrect fix for CVE-2012-5643, possibly involving an incorrect order of arguments or incorrect comparison.
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Analysis
by VulDB Data Team • 12/29/2021
The vulnerability identified as CVE-2013-0189 represents a significant security flaw in the Squid caching proxy software that affects versions 3.1.x and 3.2.x, with potential impacts extending to specific patch versions including 3.1.22 and 3.2.4. This issue manifests as a remote denial of service condition that can be triggered through carefully crafted HTTP requests, leading to excessive resource consumption on affected systems. The vulnerability specifically targets the cachemgr.cgi component within Squid, which serves as the cache manager interface for monitoring and managing the proxy cache. The flaw was introduced as an unintended consequence of an earlier fix for CVE-2012-5643, demonstrating how security patches can sometimes introduce new vulnerabilities through incorrect implementation or logic errors.
The technical root cause of this vulnerability lies in improper argument handling or incorrect comparison operations within the cachemgr.cgi script, as evidenced by the description indicating an "incorrect order of arguments or incorrect comparison." This type of flaw typically occurs when developers modify existing code to address one security issue but inadvertently introduce new logic errors that create exploitable conditions. The vulnerability operates by sending maliciously constructed requests that cause the cache manager to consume excessive system resources, potentially leading to system instability or complete service unavailability. The resource consumption aspect of this vulnerability aligns with common denial of service attack patterns where attackers exploit software logic flaws to exhaust memory, CPU cycles, or other critical system resources.
From an operational standpoint, this vulnerability presents a serious risk to organizations relying on Squid as their primary caching proxy solution, particularly in environments where continuous availability is critical. Attackers can exploit this vulnerability remotely without requiring authentication, making it especially dangerous in publicly accessible proxy configurations. The impact extends beyond simple service disruption as the resource exhaustion can potentially affect system performance, leading to cascading failures in dependent services or applications that rely on the proxy infrastructure. Organizations may experience extended downtime while investigating and resolving the issue, and the vulnerability can be particularly problematic in high-traffic environments where the denial of service can be sustained or amplified through automated attack vectors.
The remediation approach for this vulnerability requires immediate application of vendor patches or updates to Squid versions that contain proper fixes for both CVE-2013-0189 and its underlying cause CVE-2012-5643. System administrators should prioritize updating their Squid installations to versions that have been verified as free from this flaw, typically requiring careful testing to ensure that the updated patches do not introduce compatibility issues with existing proxy configurations. Network segmentation and access controls should be implemented to limit exposure of the affected cachemgr.cgi interface to trusted networks only, while monitoring should be enhanced to detect unusual resource consumption patterns that might indicate exploitation attempts. This vulnerability demonstrates the importance of thorough regression testing during security patch deployment and the potential for unintended consequences when addressing one security issue while potentially creating another. The incident also highlights the need for continuous security assessment and validation of software updates, as the flaw represents a classic example of how security fixes can sometimes introduce new attack vectors through incorrect implementation logic.