CVE-2013-0768 in Firefox
Summary
by MITRE
Stack-based buffer overflow in the Canvas implementation in Mozilla Firefox before 18.0, Firefox ESR 17.x before 17.0.2, Thunderbird before 17.0.2, Thunderbird ESR 17.x before 17.0.2, and SeaMonkey before 2.15 allows remote attackers to execute arbitrary code via an HTML document that specifies invalid width and height values.
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Analysis
by VulDB Data Team • 04/20/2021
The vulnerability CVE-2013-0768 represents a critical stack-based buffer overflow within the canvas implementation of Mozilla Firefox and related products, affecting versions prior to 18.0 and corresponding ESR releases. This flaw resides in how the browser processes canvas elements when invalid width and height parameters are specified in HTML documents, creating a potential attack vector for remote code execution. The vulnerability specifically targets the rendering engine's handling of canvas dimensions, where improper validation leads to memory corruption that can be exploited by malicious actors.
The technical implementation of this vulnerability stems from inadequate input validation within the canvas API implementation, where the browser fails to properly sanitize width and height values when constructing canvas elements. When an attacker crafts an HTML document containing malformed canvas dimensions, the application's stack memory becomes corrupted through buffer overflow conditions. This occurs because the rendering engine allocates stack space based on assumed valid dimensions, but when invalid values are provided, the system overflows into adjacent memory regions. The flaw manifests as a classic stack-based buffer overflow, which is classified under CWE-121, and represents a fundamental weakness in memory management and input validation. The attack can be executed remotely through web pages, making it particularly dangerous as it requires no user interaction beyond visiting a malicious website.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with the capability to gain complete control over affected systems. The remote code execution potential means that malicious actors can install malware, steal sensitive data, or establish persistent access to vulnerable systems. The vulnerability affects multiple Mozilla products including Firefox, Thunderbird, and SeaMonkey, creating widespread exposure across different application contexts. Security researchers have categorized this as a high-severity issue due to its remote exploitability and the potential for privilege escalation. The flaw can be leveraged in conjunction with other techniques to bypass security measures such as ASLR and DEP, making it particularly dangerous in modern threat landscapes where defense-in-depth strategies are employed.
Mitigation strategies for CVE-2013-0768 primarily focus on immediate patching and version upgrades to supported releases. Organizations should prioritize updating all affected Mozilla products to versions 18.0 or later, ensuring that ESR releases are also updated to their respective secure versions. Additional defensive measures include implementing web application firewalls to filter malicious HTML content, deploying content security policies to restrict canvas element usage, and conducting regular security assessments of web applications that may be vulnerable to similar buffer overflow conditions. Network administrators should monitor for exploitation attempts and implement intrusion detection systems that can identify malicious canvas element usage patterns. The vulnerability serves as a reminder of the importance of robust input validation and memory safety practices, aligning with ATT&CK technique T1059.007 for command and scripting interpreter usage, as attackers may leverage such vulnerabilities to execute malicious payloads through web-based attack vectors. Organizations should also consider implementing automated patch management systems to ensure timely remediation of similar vulnerabilities in the future.