CVE-2012-1962 in Firefox
Summary
by MITRE
Use-after-free vulnerability in the JSDependentString::undepend function in Mozilla Firefox 4.x through 13.0, Firefox ESR 10.x before 10.0.6, Thunderbird 5.0 through 13.0, Thunderbird ESR 10.x before 10.0.6, and SeaMonkey before 2.11 allows remote attackers to cause a denial of service (memory corruption) or possibly execute arbitrary code via vectors involving strings with multiple dependencies.
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Analysis
by VulDB Data Team • 10/21/2024
The CVE-2012-1962 vulnerability represents a critical use-after-free flaw in Mozilla's JavaScript engine that affects multiple browser products including Firefox, Thunderbird, and SeaMonkey. This vulnerability resides within the JSDependentString::undepend function which handles string dependency management in the JavaScript runtime environment. The flaw occurs when the JavaScript engine processes strings that have multiple dependencies, creating a scenario where freed memory can be accessed after it has been deallocated. This type of vulnerability falls under CWE-416 which specifically addresses use-after-free conditions, making it a prime target for exploitation by malicious actors seeking to compromise system integrity. The vulnerability is particularly dangerous because it can be triggered through web content, allowing remote attackers to exploit it without requiring local system access.
The technical implementation of this vulnerability involves the JavaScript engine's handling of dependent strings where multiple references point to the same underlying data structure. When the undepend function is called to remove dependencies from a string, it improperly manages the memory references, leading to a situation where the memory location containing the string data is freed but subsequent operations attempt to access that same memory region. This memory corruption can manifest as heap corruption, which provides attackers with opportunities to manipulate the execution flow of the application. The vulnerability is particularly insidious because it can be exploited through standard web browsing activities, making it highly relevant to the ATT&CK framework's T1203 technique for exploitation of remote services. The flaw affects a broad range of versions including Firefox 4.x through 13.0, Firefox ESR 10.x before 10.0.6, Thunderbird 5.0 through 13.0, Thunderbird ESR 10.x before 10.0.6, and SeaMonkey before 2.11, indicating the widespread nature of the issue.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enabling arbitrary code execution, making it a severe threat to user security. When exploited successfully, the memory corruption can allow attackers to inject malicious code into the browser process, potentially leading to complete system compromise. The vulnerability's remote exploitability means that users can be compromised simply by visiting malicious websites or opening specially crafted email attachments. This makes it particularly dangerous in enterprise environments where users may encounter untrusted web content regularly. The flaw's ability to cause memory corruption also means that it can be leveraged to bypass security mechanisms such as address space layout randomization and data execution prevention, as demonstrated by various exploitation techniques documented in security research. Organizations using affected versions of these Mozilla products face significant risk without immediate patching.
Mitigation strategies for CVE-2012-1962 focus primarily on immediate patching of affected software versions, as this represents the most effective defense against exploitation. Mozilla released security updates for all affected versions, and organizations should prioritize deployment of these patches across their infrastructure. Additional protective measures include implementing web application firewalls, restricting access to potentially malicious websites, and employing sandboxing techniques to limit the impact of successful exploitation attempts. Security monitoring should be enhanced to detect unusual memory access patterns or heap corruption indicators that might signal exploitation attempts. Network segmentation and access controls can help limit the potential damage from successful exploitation attempts, while regular security assessments should verify that all affected systems have been properly patched. The vulnerability's classification as a use-after-free issue also emphasizes the importance of regular code reviews and static analysis to identify similar memory management flaws in other components of the browser ecosystem.