CVE-2018-12359 in Firefox
Summary
by MITRE
A buffer overflow can occur when rendering canvas content while adjusting the height and width of the canvas element dynamically, causing data to be written outside of the currently computed boundaries. This results in a potentially exploitable crash. This vulnerability affects Thunderbird < 60, Thunderbird < 52.9, Firefox ESR < 60.1, Firefox ESR < 52.9, and Firefox < 61.
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Analysis
by VulDB Data Team • 03/29/2023
This buffer overflow vulnerability arises from improper memory management during dynamic canvas element manipulation in web browsers. The flaw occurs when the browser attempts to render canvas content while simultaneously adjusting the height and width properties of the canvas element. The underlying technical issue stems from insufficient bounds checking in the rendering engine's memory allocation routines, allowing data to be written beyond the allocated buffer boundaries. This type of vulnerability falls under the CWE-121 category of stack-based buffer overflow, though it manifests in heap memory operations during dynamic content rendering. The vulnerability specifically affects Mozilla's Gecko rendering engine which powers Firefox and Thunderbird browsers, creating a critical security risk that can be exploited through malicious web content.
The operational impact of this vulnerability extends beyond simple crash conditions to potentially enable remote code execution in targeted scenarios. When an attacker crafts malicious HTML content that dynamically modifies canvas dimensions while rendering content, the buffer overflow can corrupt adjacent memory regions and potentially overwrite critical program execution pointers. This memory corruption can lead to arbitrary code execution, allowing attackers to gain control over the affected browser process. The vulnerability affects multiple browser versions including Thunderbird versions prior to 60 and 52.9, as well as Firefox ESR versions before 60.1 and 52.9, and Firefox versions before 61, representing a significant attack surface across the Mozilla ecosystem. According to ATT&CK framework, this vulnerability maps to T1059.007 for command and scripting interpreter and T1203 for exploitation for client execution, as it enables attackers to execute arbitrary code through browser-based attacks.
Mitigation strategies for this vulnerability require immediate patching of affected browser versions to address the memory management flaw in the rendering engine. Organizations should implement browser update policies that ensure all systems are running patched versions of Firefox and Thunderbird, with particular attention to the ESR releases that address this specific buffer overflow condition. Additionally, network administrators should consider implementing web content filtering solutions that can detect and block malicious canvas manipulation patterns, though this represents a secondary mitigation approach. The fix typically involves implementing proper bounds checking before memory allocation and ensuring that dynamic canvas dimension changes are handled with appropriate memory safety mechanisms. Security teams should also monitor for exploitation attempts through threat intelligence feeds and implement intrusion detection systems that can identify suspicious canvas rendering patterns that might indicate exploitation attempts. The vulnerability demonstrates the importance of memory safety in browser rendering engines and highlights the need for continuous security auditing of core browser components that handle dynamic content manipulation.