CVE-2012-5643 in Squid
Summary
by MITRE
Multiple memory leaks in tools/cachemgr.cc in cachemgr.cgi in Squid 2.x and 3.x before 3.1.22, 3.2.x before 3.2.4, and 3.3.x before 3.3.0.2 allow remote attackers to cause a denial of service (memory consumption) via (1) invalid Content-Length headers, (2) long POST requests, or (3) crafted authentication credentials.
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Analysis
by VulDB Data Team • 04/20/2021
The vulnerability identified as CVE-2012-5643 represents a critical memory management flaw within the Squid caching proxy software that affects multiple versions across its 2.x and 3.x release lines. This issue resides in the tools/cachemgr.cc component of cachemgr.cgi, which serves as the web-based management interface for Squid cache servers. The vulnerability stems from inadequate input validation and memory handling mechanisms that fail to properly process malformed or excessive data inputs. Attackers can exploit this weakness by crafting specific malicious requests that trigger memory allocation without corresponding deallocation, leading to progressive memory exhaustion on the target system.
The technical exploitation of this vulnerability occurs through three distinct attack vectors that all leverage malformed HTTP request parameters. The first vector involves sending requests with invalid Content-Length headers that confuse the memory allocation routines within the cachemgr.cgi interface. The second vector targets long POST requests that exceed normal processing limits, causing the system to allocate memory for data that may never be properly processed or released. The third vector exploits crafted authentication credentials that trigger memory leaks during the authentication validation process. These attack methods align with CWE-401, which specifically addresses improper handling of memory allocation and deallocation in software systems. Each vector demonstrates how seemingly benign HTTP operations can be weaponized to consume system resources without proper cleanup mechanisms.
The operational impact of CVE-2012-5643 extends beyond simple denial of service conditions to potentially compromise the entire caching infrastructure. As memory consumption gradually increases through repeated exploitation attempts, the affected Squid server experiences progressive performance degradation that can eventually lead to complete system unresponsiveness. Network administrators may observe increasing memory usage patterns, system slowdowns, and potential service interruptions that affect all users relying on the caching proxy. This vulnerability particularly affects organizations that depend on Squid for content caching and web filtering operations, where sustained memory exhaustion could result in significant business disruption. The vulnerability's classification under ATT&CK technique T1499.004, which covers network denial of service, demonstrates how this memory leak can be systematically exploited to create sustained service degradation.
Mitigation strategies for CVE-2012-5643 primarily focus on immediate software updates to patched versions of Squid, specifically versions 3.1.22, 3.2.4, and 3.3.0.2 respectively. Organizations should implement network monitoring to detect unusual memory consumption patterns that may indicate exploitation attempts, particularly focusing on anomalous Content-Length header values and unusually long POST requests. Additional defensive measures include implementing request rate limiting, enforcing strict input validation for HTTP headers, and configuring proper resource limits on the caching server. System administrators should also consider implementing intrusion detection systems that can identify patterns consistent with the three identified attack vectors. The vulnerability highlights the importance of proper memory management practices and input validation in web-based management interfaces, as demonstrated by the CWE-401 classification that emphasizes the critical nature of resource leak prevention in software development lifecycle processes.