CVE-2009-3305 in Polipo
Summary
by MITRE
Polipo 1.0.4, and possibly other versions, allows remote attackers to cause a denial of service (crash) via a request with a Cache-Control header that lacks a value for the max-age field, which triggers a segmentation fault in the httpParseHeaders function in http_parse.c, and possibly other unspecified vectors.
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Analysis
by VulDB Data Team • 12/15/2024
The vulnerability identified as CVE-2009-3305 affects Polipo version 1.0.4 and potentially other releases, representing a critical denial of service weakness that can be exploited remotely by attackers. This flaw manifests when the web proxy encounters HTTP requests containing Cache-Control headers without proper max-age field values, leading to system instability and potential service disruption. The vulnerability specifically targets the httpParseHeaders function located within the http_parse.c source file, where improper handling of malformed Cache-Control headers results in segmentation faults that crash the affected service.
The technical implementation of this vulnerability stems from insufficient input validation within the HTTP header parsing mechanism. When Polipo processes an HTTP request with a Cache-Control header lacking a value for the max-age directive, the parsing function fails to properly handle the missing parameter, causing memory corruption that ultimately results in a segmentation fault. This type of flaw falls under the category of improper input validation as defined by CWE-20, specifically manifesting as a buffer overflow condition when the application attempts to access memory locations without proper bounds checking. The vulnerability demonstrates characteristics consistent with CWE-125, where out-of-bounds read conditions occur during header processing, and CWE-787, which addresses out-of-bounds writes that can occur when malformed data is processed.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise the availability of proxy services that rely on Polipo. Attackers can exploit this weakness by crafting malicious HTTP requests that specifically target the affected parsing function, causing the proxy to crash repeatedly and making it unavailable to legitimate users. This denial of service condition can be particularly damaging in environments where Polipo serves as a critical component of network infrastructure, such as in corporate proxy configurations or content filtering systems. The vulnerability's remote exploitation capability means that attackers need not have physical access to the system, making it a significant concern for publicly accessible proxy services. Additionally, the potential for unspecified vectors suggests that similar parsing issues may exist within other parts of the application, indicating a broader class of vulnerabilities that require comprehensive code review.
Mitigation strategies for this vulnerability should focus on immediate patch application from the vendor, as the issue was addressed through proper input validation and error handling within the HTTP header parsing routines. Organizations should implement network segmentation to limit exposure of vulnerable Polipo instances and consider deploying intrusion detection systems to monitor for suspicious HTTP header patterns. The fix typically involves enhancing the httpParseHeaders function to properly validate Cache-Control header formats and implement graceful error handling rather than allowing segmentation faults to occur. Security monitoring should include log analysis for malformed Cache-Control headers and unusual crash patterns. This vulnerability also highlights the importance of adhering to secure coding practices as outlined in the OWASP Secure Coding Practices, specifically regarding input validation and error handling. Organizations should conduct regular security assessments of their proxy infrastructure and implement proper software update management procedures to prevent similar vulnerabilities from affecting their systems. The ATT&CK framework categorizes this as a denial of service attack using malformed input, which can be mitigated through proper application hardening and input sanitization techniques.