CVE-2013-1677 in Firefox
Summary
by MITRE
The gfxSkipCharsIterator::SetOffsets function in Mozilla Firefox before 21.0, Firefox ESR 17.x before 17.0.6, Thunderbird before 17.0.6, and Thunderbird ESR 17.x before 17.0.6 allows remote attackers to execute arbitrary code or cause a denial of service (out-of-bounds read) via unspecified vectors.
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Analysis
by VulDB Data Team • 05/11/2021
The vulnerability identified as CVE-2013-1677 represents a critical out-of-bounds read flaw within the graphics rendering subsystem of Mozilla Firefox and Thunderbird applications. This issue resides in the gfxSkipCharsIterator::SetOffsets function which handles character iteration and offset calculations during text rendering operations. The flaw manifests when processing malformed or specially crafted input data that triggers improper memory access patterns, potentially leading to system compromise or application instability. The vulnerability affects multiple versions of Firefox and Thunderbird across both regular and extended support release channels, making it particularly widespread in affected deployments.
The technical implementation of this vulnerability stems from inadequate bounds checking within the graphics iterator component responsible for processing text character sequences. When the SetOffsets function processes input data, it fails to properly validate array indices or memory boundaries before accessing memory locations. This deficiency creates opportunities for attackers to craft malicious content that causes the application to read memory beyond allocated buffers, potentially exposing sensitive data or triggering memory corruption that can be exploited for code execution. The flaw operates at the intersection of graphics rendering and memory management, leveraging the complex interaction between text processing and graphical display components.
From an operational perspective, this vulnerability presents significant risk to end users as it can be exploited through various attack vectors including web pages, email content, or other media containing malicious text sequences. Remote attackers can leverage this flaw to execute arbitrary code on affected systems with the privileges of the user running the vulnerable application, potentially leading to full system compromise. The out-of-bounds read condition can also result in denial of service scenarios where application stability is compromised, causing crashes or unexpected behavior that disrupts normal user operations. The vulnerability's impact extends beyond individual user sessions to potentially affect enterprise environments where these applications are widely deployed.
Security professionals should implement immediate mitigations including deployment of patched versions of affected applications, as Mozilla released security updates for Firefox 21.0 and Thunderbird 17.0.6 to address this issue. Organizations should also consider network-level protections such as web application firewalls and content filtering solutions that can help detect and block malicious content targeting this vulnerability. The flaw aligns with CWE-129, which addresses improper validation of array indices, and can be mapped to ATT&CK technique T1059 for execution through command and scripting interpreters. Additionally, this vulnerability demonstrates the importance of input validation in graphics processing components and highlights the need for comprehensive memory safety testing in complex software systems where rendering engines interact with user-supplied data.