CVE-2012-1947 in Firefox
Summary
by MITRE
Heap-based buffer overflow in the utf16_to_isolatin1 function in Mozilla Firefox 4.x through 12.0, Firefox ESR 10.x before 10.0.5, Thunderbird 5.0 through 12.0, Thunderbird ESR 10.x before 10.0.5, and SeaMonkey before 2.10 allows remote attackers to execute arbitrary code via vectors that trigger a character-set conversion failure.
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Analysis
by VulDB Data Team • 10/21/2024
The vulnerability identified as CVE-2012-1947 represents a critical heap-based buffer overflow affecting multiple Mozilla products including Firefox, Thunderbird, and SeaMonkey across specific version ranges. This flaw exists within the utf16_to_isolatin1 function which handles character encoding conversions between UTF-16 and ISO Latin-1 formats. The vulnerability arises when processing malformed input data that triggers a character-set conversion failure, creating conditions where attacker-controlled data can overwrite adjacent memory locations in the heap. The technical implementation of this vulnerability falls under CWE-121, heap-based buffer overflow, which is classified as a memory safety error that occurs when more data is written to a buffer than it can hold, potentially allowing arbitrary code execution. Attackers can exploit this weakness by crafting malicious web content that when processed by the affected browsers triggers the problematic conversion function, leading to memory corruption that can be leveraged for remote code execution. The operational impact of this vulnerability extends across all affected versions of Mozilla's browser and email client products, making it particularly dangerous as it affects widely used software with broad user bases. The vulnerability's exploitation requires a remote attacker to deliver malicious content that will be processed by the affected applications, typically through web pages or email messages containing specially crafted Unicode sequences that cause the conversion failure. This attack vector aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as successful exploitation can lead to arbitrary code execution on vulnerable systems. The vulnerability's presence in Firefox 4.x through 12.0, Firefox ESR 10.x before 10.0.5, Thunderbird 5.0 through 12.0, Thunderbird ESR 10.x before 10.0.5, and SeaMonkey before 2.10 represents a significant security gap that could be exploited by threat actors to gain unauthorized access to systems. The heap-based nature of the overflow means that the memory corruption occurs in the heap memory region, which is typically used for dynamic memory allocation and can contain critical application data including pointers and control structures. When the buffer overflow occurs, it can overwrite important memory locations such as return addresses or function pointers, potentially allowing attackers to redirect program execution flow to malicious code. The character-set conversion failure that triggers this vulnerability is particularly insidious because it occurs during normal processing of web content, making it difficult to detect and prevent through conventional security measures. The exploitation of this vulnerability requires precise control over the input data to ensure that the overflow occurs in a manner that can be leveraged for code execution, typically involving careful crafting of Unicode sequences that will trigger the specific conversion path in the utf16_to_isolatin1 function. This vulnerability demonstrates the ongoing challenges in implementing secure character encoding conversions, which remain a common source of memory safety issues in web browsers and applications that process untrusted text input. The affected products' widespread use across enterprise and consumer environments makes this vulnerability particularly concerning, as successful exploitation could lead to complete system compromise. Security researchers have documented similar vulnerabilities in other applications that handle character encoding, highlighting the need for robust input validation and memory safety mechanisms in text processing functions. The fix for this vulnerability required modifications to the character conversion logic to properly validate input sizes and prevent buffer overflows during encoding operations, emphasizing the importance of proper bounds checking in memory-sensitive operations. Organizations should prioritize updating to patched versions of these applications to mitigate the risk of exploitation, as the vulnerability provides attackers with a straightforward path to remote code execution in vulnerable systems. The presence of this vulnerability in extended support releases (ESR versions) demonstrates how security issues can persist across long-term support cycles, requiring careful monitoring and timely patch management to maintain security posture. This vulnerability serves as a reminder of the critical importance of secure coding practices in applications that handle text processing, particularly in environments where untrusted input must be safely converted between different character encodings. The technical complexity of character encoding conversion functions makes them particularly prone to memory safety issues, requiring extensive testing and code review to identify potential overflow conditions. Modern security practices emphasize the need for address space layout randomization, stack canaries, and other exploit mitigations to reduce the effectiveness of buffer overflow attacks, but the fundamental issue requires proper bounds checking in the application code itself. The vulnerability's classification as a heap-based buffer overflow underscores the need for comprehensive memory safety testing and the importance of following secure coding guidelines that prevent such memory corruption issues in software development practices.