CVE-2012-0459 in Firefox
Summary
by MITRE
The Cascading Style Sheets (CSS) implementation in Mozilla Firefox 4.x through 10.0, Firefox ESR 10.x before 10.0.3, Thunderbird 5.0 through 10.0, Thunderbird ESR 10.x before 10.0.3, and SeaMonkey before 2.8 allows remote attackers to cause a denial of service (application crash) or possibly execute arbitrary code via dynamic modification of a keyframe followed by access to the cssText of the keyframe.
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Analysis
by VulDB Data Team • 10/21/2024
The vulnerability described in CVE-2012-0459 represents a critical flaw in the CSS rendering engine of multiple Mozilla applications including Firefox, Thunderbird, and SeaMonkey. This issue stems from improper handling of dynamic CSS keyframe modifications within the browser's styling engine, creating a potential vector for both denial of service attacks and arbitrary code execution. The vulnerability affects versions ranging from Firefox 4.x through 10.0, with affected ESR releases and Thunderbird versions extending the scope of impacted software. The flaw manifests when attackers manipulate CSS keyframe animations through dynamic modification followed by accessing the cssText property, which triggers memory corruption in the browser's rendering engine. This type of vulnerability falls under CWE-121, heap-based buffer overflow, and aligns with ATT&CK technique T1059.007 for command and scripting interpreter execution, as the arbitrary code execution capability could be leveraged to run malicious payloads. The technical implementation involves the interaction between JavaScript DOM manipulation and CSS object properties, specifically targeting the internal representation of CSS keyframes in the browser's memory space.
The operational impact of this vulnerability extends beyond simple application crashes, as it provides potential attackers with means to execute arbitrary code on affected systems. When a malicious web page dynamically modifies CSS keyframes and subsequently accesses the cssText property, the browser's memory management system can be exploited to overwrite critical memory locations. This memory corruption can lead to unpredictable behavior including application crashes, data corruption, or more dangerously, full system compromise when the attacker can control the execution flow. The vulnerability's exploitation requires a user to visit a malicious website or open a specially crafted email message in Thunderbird, making it particularly dangerous in phishing campaigns or drive-by download scenarios. The fact that this affects both browser and email client applications increases the attack surface significantly, as users may encounter such malicious content across different application contexts. Security researchers have noted that the memory corruption pattern suggests the vulnerability involves improper bounds checking during CSS object manipulation, which is a common pattern in buffer overflow exploits and aligns with ATT&CK technique T1068 for exploit for privilege escalation.
Mitigation strategies for CVE-2012-0459 require immediate patch application as the primary defense mechanism, with organizations urged to upgrade to patched versions of affected software. Mozilla released security updates for all impacted versions, including Firefox 10.0.3, Thunderbird 10.0.3, and SeaMonkey 2.8, which address the underlying memory corruption issue in CSS keyframe handling. System administrators should implement network-level protections such as web application firewalls and content filtering solutions to block access to known malicious domains that may exploit this vulnerability. Browser hardening measures including disabling JavaScript execution for untrusted content, implementing sandboxing mechanisms, and using security extensions like NoScript or XSS Hunter can provide additional defense layers. Organizations should also conduct security awareness training to educate users about avoiding suspicious websites and email attachments, as social engineering remains a critical component in successful exploitation of such vulnerabilities. The vulnerability demonstrates the importance of proper input validation in web browser implementations and highlights the need for comprehensive memory safety testing of CSS rendering engines, particularly when dealing with dynamic content manipulation features that expose internal browser objects to JavaScript execution contexts. Regular security assessments and vulnerability scanning should include checks for outdated browser versions that may still be vulnerable to this and similar memory corruption issues.