CVE-2011-3205 in Squid
Summary
by MITRE
Buffer overflow in the gopherToHTML function in gopher.cc in the Gopher reply parser in Squid 3.0 before 3.0.STABLE26, 3.1 before 3.1.15, and 3.2 before 3.2.0.11 allows remote Gopher servers to cause a denial of service (memory corruption and daemon restart) or possibly have unspecified other impact via a long line in a response. NOTE: This issue exists because of a CVE-2005-0094 regression.
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Analysis
by VulDB Data Team • 03/19/2021
The vulnerability described in CVE-2011-3205 represents a critical buffer overflow condition within Squid's Gopher protocol handling mechanism, specifically affecting the gopherToHTML function in gopher.cc. This flaw emerges in Squid versions prior to the mentioned stable releases, creating a persistent security risk that has significant implications for web proxy and caching systems relying on Gopher protocol support. The vulnerability stems from a regression introduced in CVE-2005-0094, which inadvertently reintroduced memory handling issues that were previously addressed, demonstrating how security patches can sometimes create new vulnerabilities through unintended consequences.
The technical implementation of this buffer overflow occurs within the Gopher reply parser where the gopherToHTML function processes responses from remote Gopher servers. When a remote server sends a response containing an excessively long line, the function fails to properly validate input length before copying data into a fixed-size buffer. This classic buffer overflow condition results in memory corruption that can trigger unpredictable behavior including daemon crashes and automatic restarts, effectively causing a denial of service condition. The vulnerability's impact extends beyond simple service disruption as the memory corruption could potentially enable more sophisticated attacks depending on the execution environment and memory layout.
From an operational perspective, this vulnerability poses significant risks to organizations relying on Squid as their primary web proxy or caching solution, particularly those that may encounter Gopher servers in their network traffic or have Gopher protocol support enabled for legacy compatibility. The remote nature of the attack means that any system processing Gopher responses could be compromised without direct user interaction, making it particularly dangerous in environments where automatic proxy configuration or transparent proxying is in use. The potential for unspecified other impacts suggests that attackers might be able to leverage this vulnerability for privilege escalation or code execution depending on the system configuration and memory protection mechanisms in place.
Organizations should prioritize immediate patching of affected Squid installations to address this vulnerability, with particular attention to the specific version ranges mentioned in the CVE description. The mitigation strategy should include not only applying the appropriate security patches but also implementing network segmentation to limit exposure to potentially malicious Gopher servers. Security monitoring should be enhanced to detect unusual proxy behavior or service restarts that might indicate exploitation attempts. This vulnerability aligns with CWE-121 and CWE-122 categories related to buffer overflow conditions, and could potentially map to ATT&CK techniques involving privilege escalation and denial of service through memory corruption attacks. Regular security audits of proxy configurations and input validation mechanisms should be conducted to prevent similar regressions from occurring in the future.