CVE-2012-4504 in libproxy
Summary
by MITRE
Stack-based buffer overflow in the url::get_pac function in url.cpp in libproxy 0.4.x before 0.4.9 allows remote servers to have an unspecified impact via a large proxy.pac file.
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Analysis
by VulDB Data Team • 12/19/2021
The vulnerability identified as CVE-2012-4504 represents a critical stack-based buffer overflow flaw within the libproxy library version 0.4.x prior to 0.4.9. This vulnerability specifically affects the url::get_pac function located in the url.cpp source file, creating a dangerous condition that can be exploited by remote attackers through maliciously crafted proxy.pac files. The issue stems from insufficient input validation and bounds checking within the function that processes proxy auto-configuration files, which are commonly used to automate proxy server selection in network environments.
The technical implementation of this vulnerability involves the manipulation of proxy.pac files to trigger a buffer overflow condition in the stack memory of applications using libproxy. When a remote server delivers an oversized proxy.pac file, the url::get_pac function fails to properly validate the input size before attempting to process it, leading to memory corruption that can result in arbitrary code execution or application crashes. This flaw directly corresponds to CWE-121 Stack-based Buffer Overflow, which is classified as a critical weakness in software security. The vulnerability's impact is particularly severe because proxy.pac files are commonly used in enterprise environments and web browsers, making the attack surface wide and potentially affecting numerous applications that depend on libproxy for network configuration management.
The operational implications of this vulnerability extend beyond simple application instability to encompass potential security breaches and system compromise. Attackers can leverage this flaw to execute malicious code on systems that process proxy.pac files, potentially gaining unauthorized access to sensitive network resources or elevating privileges within the affected applications. The unspecified impact mentioned in the CVE description suggests that the vulnerability could enable various attack vectors including denial of service, privilege escalation, or remote code execution depending on the specific implementation and system configuration. This vulnerability aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter, as it could enable attackers to execute arbitrary commands through compromised applications that utilize the vulnerable libproxy library.
Mitigation strategies for CVE-2012-4504 require immediate patching of all affected libproxy installations to version 0.4.9 or later, which contains the necessary fixes to prevent the buffer overflow condition. Organizations should conduct comprehensive inventory audits to identify all systems and applications that depend on libproxy, particularly those that process external proxy.pac files. Network administrators should implement additional security controls such as proxy.pac file validation and size restrictions to prevent the processing of suspiciously large files. The vulnerability also highlights the importance of input validation and proper memory management practices in network security libraries, emphasizing the need for regular security assessments of third-party components. System administrators should monitor for any signs of exploitation attempts and implement network segmentation to limit the potential impact of successful attacks. Additionally, organizations should consider implementing automated patch management processes to ensure timely deployment of security updates and reduce the window of vulnerability exposure.