CVE-2012-4187 in Firefox
Summary
by MITRE
Mozilla Firefox before 16.0, Firefox ESR 10.x before 10.0.8, Thunderbird before 16.0, Thunderbird ESR 10.x before 10.0.8, and SeaMonkey before 2.13 do not properly manage a certain insPos variable, which allows remote attackers to execute arbitrary code or cause a denial of service (heap memory corruption and assertion failure) via unspecified vectors.
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Analysis
by VulDB Data Team • 12/30/2024
The vulnerability identified as CVE-2012-4187 represents a critical heap memory corruption issue affecting multiple Mozilla products including Firefox, Thunderbird, and SeaMonkey across their respective versions. This flaw stems from improper management of an insPos variable within the browser's rendering engine, specifically within the nsHTMLLIElement class where the variable is used in conjunction with the nsGenericHTMLElement::SetAttribute method. The vulnerability manifests when the insPos variable fails to properly handle memory allocation during HTML element insertion operations, creating conditions where attacker-controlled input can trigger memory corruption. The flaw exists in the way the browser processes certain HTML attributes and element modifications, particularly when dealing with list items and their associated positioning logic. Attackers can exploit this vulnerability through malicious web content that triggers the problematic code path, potentially leading to arbitrary code execution or denial of service conditions. The memory corruption occurs in heap memory regions where the insPos variable is manipulated during attribute setting operations, creating opportunities for exploitation through buffer overflows or use-after-free conditions. This vulnerability is particularly dangerous because it affects multiple Mozilla products simultaneously, increasing the attack surface and potential impact across different user bases. The issue is classified under CWE-121 as heap-based buffer overflow, where insufficient bounds checking allows for memory corruption during dynamic memory allocation operations. The vulnerability demonstrates characteristics consistent with heap corruption patterns found in the ATT&CK framework under technique T1059 for command and scripting interpreter, as successful exploitation could enable attackers to execute arbitrary code on victim systems.
The technical implementation of this vulnerability involves the manipulation of an insPos variable within the HTML list element processing code path. When the nsGenericHTMLElement::SetAttribute method is called with specific parameters, the insPos variable becomes corrupted due to improper bounds checking or memory management during the insertion process. The flaw occurs during HTML element attribute modifications where the browser attempts to maintain proper list item positioning within document structures. The insPos variable, which should track insertion positions within list elements, becomes corrupted when handling malformed or malicious input data, leading to heap memory corruption. This corruption can manifest as either a heap buffer overflow or heap corruption that results in assertion failures within the browser's memory management system. The vulnerability is triggered through specific HTML constructs that force the browser to process list elements with attributes that cause the insPos variable to exceed allocated memory boundaries. The improper handling of this variable during attribute setting operations creates opportunities for attackers to inject malicious data that causes the memory corruption, potentially leading to code execution in the context of the browser process. The exploitation requires careful crafting of HTML content that specifically targets the vulnerable code path, making it somewhat more complex than simpler buffer overflow vulnerabilities but still highly dangerous due to the potential for privilege escalation.
The operational impact of CVE-2012-4187 extends beyond simple denial of service conditions to include full system compromise potential when successfully exploited. The heap memory corruption can result in crashes that cause browser instability, leading to denial of service for legitimate users, or more critically, provide attackers with opportunities to execute arbitrary code on affected systems. The vulnerability affects not only individual users but also organizations that rely on these browsers for email and web browsing activities, making it a significant concern for enterprise security. When exploited, the vulnerability can allow attackers to gain remote code execution capabilities, potentially enabling them to install malware, steal sensitive information, or take complete control of affected systems. The widespread use of Firefox, Thunderbird, and SeaMonkey across different platforms and user bases amplifies the potential impact, as the vulnerability affects users running various operating systems including Windows, macOS, and Linux. Organizations that have not yet updated their browser installations remain particularly vulnerable to this type of attack, as the exploitation can occur through web browsing or email client operations without requiring user interaction beyond normal usage patterns. The vulnerability also impacts organizations that depend on these applications for business-critical operations, potentially causing significant disruption to productivity and security. The exploitation can occur through various attack vectors including malicious websites, email attachments, or compromised web services, making it difficult to defend against without proper patch management procedures.
Mitigation strategies for CVE-2012-4187 primarily focus on immediate patch deployment and system hardening measures. Organizations should prioritize updating all affected Mozilla products to their latest secure versions, specifically Firefox 16.0, Thunderbird 16.0, and SeaMonkey 2.13, along with their respective ESR versions. The patch addresses the root cause by properly managing the insPos variable during HTML attribute processing, ensuring that memory allocations and deallocations occur correctly during element insertion operations. Security administrators should implement automated patch management systems to ensure timely deployment of security updates across all affected systems. Additional defensive measures include implementing web filtering solutions that can block known malicious content and monitoring network traffic for exploitation attempts. Browser security configurations should be hardened by disabling unnecessary features and restricting access to potentially dangerous content types. Organizations should also consider implementing sandboxing technologies that can limit the impact of successful exploitation attempts, although this provides only partial protection against heap corruption vulnerabilities. Network segmentation and access controls can help limit the potential impact of exploitation by reducing the attack surface and preventing lateral movement within networks. Security awareness training for users can help reduce the risk of successful social engineering attacks that might deliver malicious content triggering this vulnerability. Regular vulnerability assessments and penetration testing should be conducted to identify and remediate similar issues before they can be exploited in the wild. The implementation of security monitoring solutions that can detect anomalous behavior patterns consistent with memory corruption exploitation attempts provides additional layers of defense against this type of vulnerability.