CVE-2012-2813 in libexif
Summary
by MITRE
The exif_convert_utf16_to_utf8 function in exif-entry.c in the EXIF Tag Parsing Library (aka libexif) before 0.6.21 allows remote attackers to cause a denial of service (out-of-bounds read) or possibly obtain sensitive information from process memory via crafted EXIF tags in an image.
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Analysis
by VulDB Data Team • 12/06/2021
The vulnerability identified as CVE-2012-2813 affects the EXIF Tag Parsing Library commonly known as libexif, specifically targeting the exif_convert_utf16_to_utf8 function within the exif-entry.c source file. This flaw exists in versions prior to 0.6.21 and represents a critical security issue that can be exploited remotely by attackers who craft malicious EXIF metadata within image files. The vulnerability stems from inadequate input validation and memory handling within the library's text conversion routines, creating a scenario where malformed UTF-16 encoded data can trigger unexpected behavior in the parsing process.
The technical implementation of this vulnerability involves a classic out-of-bounds read condition that occurs when the exif_convert_utf16_to_utf8 function attempts to process UTF-16 encoded strings without proper bounds checking. When an attacker supplies crafted EXIF tags containing malformed UTF-16 sequences, the function accesses memory locations beyond the allocated buffer boundaries, leading to either a denial of service condition where the application crashes or potentially sensitive information leakage from adjacent memory regions. This type of vulnerability falls under the CWE-125 Out-of-Bounds Read category, which is classified as a memory safety issue in the Common Weakness Enumeration catalog, and represents a fundamental flaw in how the library handles character encoding conversions.
The operational impact of CVE-2012-2813 extends beyond simple service disruption to potentially expose sensitive data from process memory, making it particularly dangerous in environments where image processing applications handle untrusted user uploads. Systems utilizing libexif for image metadata extraction, including web applications, content management systems, and digital asset management platforms, become vulnerable to this attack vector. The vulnerability can be exploited through various image formats that support EXIF metadata such as jpeg, tiff, and other formats that incorporate EXIF data, making it a widespread concern across digital media processing infrastructure. According to ATT&CK framework categorization, this vulnerability maps to T1059 Command and Scripting Interpreter and T1499 Endpoint Denial of Service, as it enables both service disruption and potential information disclosure attacks.
Mitigation strategies for this vulnerability require immediate patching of affected libexif installations to version 0.6.21 or later, which includes proper bounds checking and input validation for UTF-16 to UTF-8 conversion routines. Organizations should also implement input sanitization measures at network boundaries, particularly for image uploads in web applications, by validating and normalizing EXIF metadata before processing. Additional protective measures include deploying web application firewalls that can detect and block suspicious image file patterns, implementing strict file type validation, and ensuring that image processing applications run with minimal privileges to limit potential damage from successful exploitation. The fix implemented in libexif 0.6.21 specifically addresses the buffer overflow condition by introducing proper boundary checks and robust error handling for malformed UTF-16 sequences, thereby eliminating the conditions that previously enabled both denial of service and information disclosure attacks.