CVE-2012-4409 in mcrypt
Summary
by MITRE
Stack-based buffer overflow in the check_file_head function in extra.c in mcrypt 2.6.8 and earlier allows user-assisted remote attackers to execute arbitrary code via an encrypted file with a crafted header containing long salt data that is not properly handled during decryption.
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Analysis
by VulDB Data Team • 12/29/2024
The CVE-2012-4409 vulnerability represents a critical stack-based buffer overflow flaw in the mcrypt library version 2.6.8 and earlier implementations. This vulnerability exists within the check_file_head function located in the extra.c source file, where the software fails to properly validate input data during the decryption process. The flaw specifically manifests when processing encrypted files that contain crafted headers with excessively long salt data, creating a condition where attacker-controlled input can overwrite adjacent stack memory locations beyond the allocated buffer boundaries.
The technical exploitation of this vulnerability occurs through a user-assisted remote attack vector where an attacker can craft a malicious encrypted file with an oversized salt field in the file header. When the mcrypt library attempts to process this file, the check_file_head function does not perform adequate bounds checking on the salt data length, allowing the buffer overflow to occur during the decryption operation. This overflow can overwrite return addresses, function pointers, and other critical stack variables, potentially enabling arbitrary code execution with the privileges of the process running the vulnerable mcrypt library.
The operational impact of CVE-2012-4409 extends beyond simple privilege escalation as it affects any system utilizing the vulnerable mcrypt library for decryption operations. The vulnerability is particularly concerning because it can be triggered through legitimate file processing operations, making it difficult to detect in normal system behavior. Systems that process untrusted encrypted files, such as email servers, file transfer applications, or any software that uses mcrypt for decryption, become potential targets for exploitation. The vulnerability can be exploited by attackers who have the ability to place malicious encrypted files on systems where mcrypt is used, either through direct file placement or by influencing the download of compromised files.
Security mitigations for this vulnerability require immediate patching of the mcrypt library to version 2.6.9 or later, which includes proper bounds checking and input validation for salt data handling. Organizations should also implement strict file validation procedures for any encrypted files processed by systems using mcrypt, particularly those from untrusted sources. Network-based protections can include monitoring for suspicious file transfer activities and implementing file type validation to prevent processing of potentially malicious encrypted files. From a compliance perspective, this vulnerability aligns with CWE-121 stack-based buffer overflow weakness and represents a significant risk under ATT&CK framework's execution and privilege escalation techniques. The vulnerability demonstrates the importance of proper input validation and memory management practices in cryptographic libraries, as highlighted in industry standards for secure coding practices and vulnerability management protocols.