CVE-2013-0771 in Firefox
Summary
by MITRE
Heap-based buffer overflow in the gfxTextRun::ShrinkToLigatureBoundaries function in Mozilla Firefox before 18.0, Firefox ESR 17.x before 17.0.1, Thunderbird before 17.0.2, Thunderbird ESR 17.x before 17.0.1, and SeaMonkey before 2.15 allows remote attackers to execute arbitrary code via a crafted document.
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Analysis
by VulDB Data Team • 04/20/2021
The vulnerability identified as CVE-2013-0771 represents a critical heap-based buffer overflow affecting Mozilla Firefox and related applications prior to specific version releases. This flaw exists within the gfxTextRun::ShrinkToLigatureBoundaries function, which handles text rendering operations in the browser's graphics subsystem. The vulnerability arises from insufficient bounds checking when processing text elements that contain ligature boundaries, creating an exploitable condition that can be triggered through maliciously crafted web content.
The technical implementation of this vulnerability stems from improper memory management within the text rendering pipeline. When the gfxTextRun::ShrinkToLigatureBoundaries function processes text containing specific character sequences that form ligatures, it fails to validate the boundaries of heap-allocated memory regions. This allows attackers to write beyond allocated buffer limits, potentially overwriting adjacent memory locations with malicious data. The flaw specifically manifests when processing complex text layouts that require ligature handling, making it particularly relevant to international character sets and typography-heavy web content.
From an operational perspective, this vulnerability presents a severe remote code execution risk that can be exploited through web-based attacks. Attackers can craft malicious HTML documents containing specially formatted text that, when rendered by vulnerable browsers, triggers the buffer overflow condition. The exploitability of this flaw is enhanced by the fact that it operates within the browser's core rendering engine, meaning successful exploitation can lead to complete system compromise without requiring user interaction beyond visiting a malicious website. The vulnerability affects multiple Mozilla products including Firefox, Thunderbird, and SeaMonkey, creating widespread potential impact across different application domains.
The security implications of CVE-2013-0771 align with CWE-121, heap-based buffer overflow, and demonstrates characteristics consistent with ATT&CK technique T1059.1.001 for command and scripting interpreter. Organizations affected by this vulnerability face significant risk of unauthorized code execution, data theft, and system compromise. The flaw represents a classic example of how text processing libraries can introduce critical security vulnerabilities when proper input validation and memory bounds checking are insufficiently implemented.
Mitigation strategies for this vulnerability require immediate patching of affected software versions to the recommended secure releases. System administrators should prioritize updating Firefox 18.0, Thunderbird 17.0.2, and SeaMonkey 2.15, along with their respective ESR versions. Additionally, organizations should implement network-level protections including web application firewalls and content filtering systems that can detect and block malicious text-based content. Browser hardening measures such as disabling unnecessary text rendering features and implementing strict sandboxing policies can provide additional defense-in-depth protection against exploitation attempts. The vulnerability serves as a reminder of the critical importance of thorough memory management practices in graphics and text rendering components of browser applications.