CVE-2005-0175 in Squid
Summary
by MITRE
Squid 2.5 up to 2.5.STABLE7 allows remote attackers to poison the cache via an HTTP response splitting attack.
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Analysis
by VulDB Data Team • 12/16/2024
The vulnerability described in CVE-2005-0175 represents a critical security flaw in Squid proxy server versions 2.5 through 2.5.STABLE7 that enables remote attackers to perform HTTP response splitting attacks. This vulnerability occurs within the HTTP protocol handling mechanisms of the proxy server, specifically in how it processes and caches HTTP responses. The flaw allows malicious actors to inject malicious content into the proxy cache by manipulating HTTP response headers, potentially leading to various downstream security issues including cross-site scripting attacks, session hijacking, and cache poisoning. The vulnerability is classified under CWE-110, which specifically addresses HTTP response splitting, and aligns with ATT&CK technique T1190 for exploitation of vulnerabilities in proxy services.
The technical implementation of this vulnerability stems from insufficient input validation and sanitization of HTTP response headers within the Squid proxy server's caching mechanism. When processing HTTP responses, the proxy server fails to properly validate or sanitize header values that contain special characters or sequences that could be interpreted as delimiters or control characters in HTTP protocol parsing. Attackers can exploit this weakness by crafting malicious HTTP responses that contain carriage return and line feed characters within response headers, effectively splitting the HTTP response into multiple parts. This manipulation allows attackers to inject arbitrary content into the cache, which can then be served to unsuspecting users who access the cached content through the vulnerable proxy server.
The operational impact of this vulnerability extends beyond simple cache poisoning, creating significant risks for organizations relying on Squid as their primary proxy infrastructure. When successful, HTTP response splitting attacks can enable attackers to redirect users to malicious websites, inject malicious scripts into web pages, or steal session cookies and other sensitive information. The cached malicious content can persist for extended periods depending on cache expiration policies, potentially affecting numerous users over time. Organizations may experience reputational damage, regulatory compliance issues, and potential data breaches when this vulnerability is exploited. The vulnerability particularly affects web applications that depend on Squid for content caching and proxy services, making it a critical concern for enterprises with extensive proxy infrastructure deployments.
Mitigation strategies for CVE-2005-0175 require immediate action to address the underlying vulnerability through software updates and configuration hardening. Organizations should upgrade to Squid versions that have patched this vulnerability, specifically versions beyond 2.5.STABLE7, as these releases contain proper input validation mechanisms for HTTP headers. Network administrators should implement additional security controls including HTTP header sanitization rules, content filtering mechanisms, and regular monitoring of cache content for suspicious entries. The implementation of proper input validation and sanitization at the proxy level can prevent malicious header sequences from being processed and cached. Security teams should also consider implementing web application firewalls and intrusion detection systems to monitor for patterns indicative of HTTP response splitting attempts. The vulnerability demonstrates the critical importance of maintaining up-to-date proxy server software and implementing defense-in-depth strategies to protect against protocol-level attacks that can compromise entire network infrastructures.