CVE-2005-0174 in Squid
Summary
by MITRE
Squid 2.5 up to 2.5.STABLE7 allows remote attackers to poison the cache or conduct certain attacks via headers that do not follow the HTTP specification, including (1) multiple Content-Length headers, (2) carriage return (CR) characters that are not part of a CRLF pair, and (3) header names containing whitespace characters.
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Analysis
by VulDB Data Team • 12/16/2024
The vulnerability described in CVE-2005-0174 affects Squid proxy servers version 2.5 through 2.5.STABLE7, representing a significant security flaw in HTTP header processing that can be exploited remotely by attackers to manipulate cache content and potentially conduct broader attacks. This vulnerability stems from the proxy server's insufficient validation of HTTP headers, specifically targeting three distinct patterns of non-compliant header structures that violate the HTTP specification. The flaw allows malicious actors to inject crafted headers that exploit parsing inconsistencies within the Squid implementation, creating opportunities for cache poisoning and other attack vectors that compromise the integrity of the proxy's caching mechanism.
The technical implementation of this vulnerability involves three specific header anomalies that Squid fails to properly validate or reject during HTTP request processing. The first issue occurs with multiple Content-Length headers within a single HTTP request, a scenario that violates HTTP specification requirements where only one Content-Length header should be present. The second vulnerability involves carriage return characters that appear outside of proper CRLF (Carriage Return Line Feed) pairs, a technique that can be used to manipulate header parsing and potentially inject additional content. The third problematic pattern involves header names containing whitespace characters, which creates parsing ambiguities that attackers can exploit to manipulate how the proxy server processes and stores cached content. These three distinct header manipulation techniques all fall under the category of HTTP header injection and parsing errors that can be leveraged to compromise proxy server functionality.
The operational impact of this vulnerability extends beyond simple cache poisoning to potentially enable more sophisticated attacks against web applications and users relying on the proxy server. When attackers successfully exploit these header parsing flaws, they can manipulate cached content to serve malicious data to users, potentially redirecting traffic to malicious sites or injecting harmful content into web pages. The vulnerability's remote exploitability means that attackers do not need physical access to the network or direct system access to cause damage, making it particularly dangerous in environments where Squid serves as a critical caching or filtering proxy. This weakness can be exploited to bypass security controls, conduct man-in-the-middle attacks, or manipulate the flow of data through the proxy infrastructure, particularly affecting organizations that depend on Squid for web filtering, caching optimization, or traffic management.
Organizations affected by this vulnerability should prioritize immediate remediation through software updates to versions of Squid that properly validate HTTP headers and reject malformed content. The recommended mitigation strategy involves upgrading to Squid versions beyond 2.5.STABLE7 where these header validation issues have been addressed. Security teams should also implement additional monitoring to detect anomalous HTTP header patterns that might indicate exploitation attempts, and consider deploying web application firewalls or proxy security solutions that can filter out suspicious header structures. This vulnerability aligns with CWE-1030 and CWE-1031 categories related to HTTP header injection and parsing errors, and can be mapped to ATT&CK techniques involving proxy manipulation and cache poisoning. Organizations should conduct thorough vulnerability assessments to identify any systems running affected Squid versions and implement proper input validation controls to prevent similar header parsing issues in other network infrastructure components.