CVE-2005-0241 in Squid
Summary
by MITRE
The httpProcessReplyHeader function in http.c for Squid 2.5-STABLE7 and earlier does not properly set the debug context when it is handling "oversized" HTTP reply headers, which might allow remote attackers to poison the cache or bypass access controls based on header size.
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Analysis
by VulDB Data Team • 12/16/2024
The vulnerability described in CVE-2005-0241 resides within the Squid web proxy server software, specifically in the http.c source file where the httpProcessReplyHeader function operates. This flaw affects Squid versions 2.5-STABLE7 and earlier, representing a significant security weakness that could be exploited by remote attackers to manipulate the caching behavior of the proxy server. The issue stems from improper handling of HTTP reply headers that exceed normal size limits, creating a potential vector for cache poisoning attacks and access control bypasses that could compromise the integrity of the proxy's caching mechanism.
The technical implementation of this vulnerability involves the httpProcessReplyHeader function failing to correctly establish the debug context when processing oversized HTTP reply headers. This malfunction occurs during the header processing phase where the function should maintain proper state information for debugging purposes but instead creates an inconsistent debug context. When HTTP reply headers exceed predetermined size thresholds, the function's handling of these oversized elements becomes problematic, leading to potential state corruption that could be leveraged by attackers. The failure to properly manage the debug context essentially creates a condition where the proxy server's internal state becomes unpredictable when encountering unusually large headers.
The operational impact of this vulnerability extends beyond simple cache corruption, as it enables attackers to potentially bypass access controls that are typically enforced based on header size limitations. This creates a scenario where malicious actors could craft HTTP responses with oversized headers to manipulate how the proxy server processes and caches content, potentially allowing unauthorized access to protected resources or enabling cache poisoning attacks that could affect multiple users. The vulnerability essentially undermines the proxy server's ability to properly enforce security policies and maintain consistent caching behavior, particularly when processing responses from potentially malicious sources.
Organizations utilizing affected Squid versions should implement immediate mitigations including upgrading to patched versions of the software, as the vulnerability was addressed in subsequent releases. Network administrators should also consider implementing additional monitoring and logging mechanisms to detect unusual header size patterns that might indicate exploitation attempts. The vulnerability aligns with CWE-122, which describes "Heap Overflow" conditions that can occur when buffer management fails, and relates to ATT&CK technique T1071.004, which covers application layer protocol manipulation. Security teams should also consider implementing rate limiting and header size validation mechanisms as additional defensive measures to prevent exploitation of this class of vulnerability.