CVE-2012-3960 in Firefox
Summary
by MITRE
Use-after-free vulnerability in the mozSpellChecker::SetCurrentDictionary function in Mozilla Firefox before 15.0, Firefox ESR 10.x before 10.0.7, Thunderbird before 15.0, Thunderbird ESR 10.x before 10.0.7, and SeaMonkey before 2.12 allows remote attackers to execute arbitrary code or cause a denial of service (heap memory corruption) via unspecified vectors.
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Analysis
by VulDB Data Team • 10/22/2024
The CVE-2012-3960 vulnerability represents a critical use-after-free flaw within Mozilla's spell checking implementation that affected multiple browser and email client products including Firefox, Thunderbird, and SeaMonkey. This vulnerability resides in the mozSpellChecker::SetCurrentDictionary function which handles dictionary switching operations during spell checking processes. The flaw occurs when the application attempts to access memory that has already been freed, creating a dangerous condition that can be exploited by remote attackers to execute arbitrary code or cause system instability.
The technical nature of this vulnerability falls under the CWE-416 category of Use After Free, where memory that has been deallocated is still referenced by the application. In the context of Mozilla's spell checking system, when SetCurrentDictionary is called to switch between different dictionary files, the application fails to properly manage the memory lifecycle of dictionary objects. This improper memory management creates a scenario where freed memory chunks can be reallocated and subsequently accessed by malicious code, leading to heap corruption that can be leveraged for code execution.
The operational impact of this vulnerability extends beyond simple exploitation capabilities to include significant security risks for users of affected Mozilla products. Attackers can craft malicious web content or email messages that trigger the vulnerable spell checking functionality, potentially leading to complete system compromise when users interact with such content. The vulnerability affects not just regular Firefox users but also those using Firefox ESR, Thunderbird, and SeaMonkey products, creating a broad attack surface that spans multiple Mozilla applications. The heap memory corruption resulting from this flaw can manifest as unpredictable application behavior, crashes, or more dangerously, provide attackers with opportunities to inject and execute malicious code within the context of the affected applications.
Mitigation strategies for CVE-2012-3960 primarily focus on immediate product updates and patches released by Mozilla to address the memory management issues in the spell checking component. Organizations should prioritize updating all affected versions to the patched releases including Firefox 15.0, Thunderbird 15.0, and SeaMonkey 2.12, along with their respective ESR versions. Additional defensive measures include implementing content filtering solutions that can detect and block potentially malicious spell checking operations, enabling sandboxing features where available, and monitoring for unusual application behavior that might indicate exploitation attempts. The vulnerability also highlights the importance of proper memory management practices in security-critical components and aligns with ATT&CK techniques related to memory corruption exploits and privilege escalation through application vulnerabilities.