CVE-2002-0713 in Squid
Summary
by MITRE
Buffer overflows in Squid before 2.4.STABLE6 allow remote attackers to cause a denial of service (crash) and possibly execute arbitrary code (1) via the MSNT auth helper (msnt_auth) when using denyusers or allowusers files, (2) via the gopher client, or (3) via the FTP server directory listing parser when HTML output is generated.
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Analysis
by VulDB Data Team • 05/09/2019
The vulnerability identified as CVE-2002-0713 represents a critical buffer overflow issue affecting Squid proxy server versions prior to 2.4.STABLE6. This vulnerability resides within multiple components of the Squid software including the MSNT authentication helper, gopher client implementation, and FTP server directory listing parser. The buffer overflow conditions occur when processing user input in these specific modules, creating opportunities for remote attackers to manipulate memory allocation and potentially execute malicious code. The flaw specifically manifests when Squid processes denyusers or allowusers files through the msnt_auth helper, handles gopher protocol requests, or generates HTML output during FTP directory listings.
The technical exploitation of this vulnerability follows established patterns of buffer overflow attacks that fall under CWE-121, which describes heap-based buffer overflow conditions. When the MSNT auth helper processes user credentials from denyusers or allowusers files, insufficient bounds checking allows attackers to overwrite adjacent memory locations, potentially leading to program termination or code execution. Similarly, the gopher client and FTP server directory listing parser components lack proper input validation mechanisms when handling user-supplied data, creating identical attack vectors. These buffer overflows represent a fundamental failure in input sanitization and memory management practices that violate security principles outlined in the OWASP Top Ten and other industry standards for secure coding practices.
The operational impact of CVE-2002-0713 extends beyond simple denial of service conditions, as the vulnerability presents potential for remote code execution within the target system. Attackers exploiting these buffer overflows can cause the Squid proxy to crash and potentially gain unauthorized access to the underlying system through code execution capabilities. This represents a significant risk to network infrastructure since Squid servers often serve as critical components in enterprise proxy and caching environments. The vulnerability affects systems where Squid is configured to use MSNT authentication, handle gopher protocol requests, or generate HTML output for FTP directory listings, making it particularly dangerous in environments with multiple protocol support enabled.
Mitigation strategies for CVE-2002-0713 primarily focus on immediate software updates and configuration hardening. Organizations should upgrade to Squid version 2.4.STABLE6 or later, which contains patches addressing the specific buffer overflow conditions. Additionally, implementing proper input validation and bounds checking mechanisms in custom configurations can provide temporary protection while awaiting updates. Network segmentation and access controls should limit exposure to these vulnerable components, particularly disabling unnecessary protocol support such as gopher and FTP directory listing HTML generation when not required. The vulnerability demonstrates the importance of maintaining current software versions and implementing robust security monitoring to detect potential exploitation attempts. Security teams should also consider implementing intrusion detection systems that can identify suspicious patterns associated with buffer overflow exploitation attempts, particularly those targeting authentication helpers and protocol handlers. The ATT&CK framework categorizes this vulnerability under privilege escalation and denial of service tactics, emphasizing the need for comprehensive security controls that address both availability and integrity concerns in proxy server environments.