CVE-2012-2841 in libexif
Summary
by MITRE
Integer underflow in the exif_entry_get_value function in exif-entry.c in the EXIF Tag Parsing Library (aka libexif) 0.6.20 might allow remote attackers to execute arbitrary code via vectors involving a crafted buffer-size parameter during the formatting of an EXIF tag, leading to a heap-based buffer overflow.
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Analysis
by VulDB Data Team • 12/06/2021
The vulnerability identified as CVE-2012-2841 represents a critical integer underflow flaw within the EXIF Tag Parsing Library version 0.6.20, specifically within the exif_entry_get_value function located in exif-entry.c. This vulnerability arises from improper input validation when processing EXIF metadata within image files, creating a scenario where a maliciously crafted buffer-size parameter can trigger a heap-based buffer overflow condition. The flaw demonstrates characteristics consistent with CWE-128, which addresses unsigned integer underflow conditions, and aligns with ATT&CK technique T1203 for exploitation of input validation vulnerabilities in image processing libraries.
The technical execution of this vulnerability involves an attacker constructing a specially formatted EXIF tag with manipulated buffer size parameters that, when processed by the vulnerable libexif library, causes an integer underflow condition. This underflow results in a negative buffer size value being passed to memory allocation functions, subsequently leading to heap corruption and potential arbitrary code execution. The vulnerability is particularly dangerous because it can be triggered during routine image processing operations, making it exploitable through common attack vectors such as web browsing, email attachment processing, or image file handling in applications that utilize libexif for metadata parsing.
From an operational impact perspective, this vulnerability poses significant risks to systems that process untrusted image files, including web applications, email servers, image processing services, and digital asset management systems. The heap-based buffer overflow creates opportunities for remote code execution, privilege escalation, and denial of service conditions, making it a highly attractive target for attackers seeking to compromise systems through image file manipulation. The vulnerability's exploitation requires minimal user interaction beyond the mere opening or processing of a malicious image file, making it particularly dangerous in automated processing environments.
Mitigation strategies for CVE-2012-2841 should prioritize immediate patching of affected libexif installations to version 0.6.21 or later, which contains the necessary fixes for the integer underflow condition. Organizations should also implement defensive measures such as input validation for image metadata, sandboxed processing environments for untrusted image files, and regular security assessments of image processing pipelines. Network segmentation and access controls can help limit the potential impact of successful exploitation, while monitoring systems should be configured to detect unusual image processing activities that might indicate exploitation attempts. The vulnerability highlights the importance of robust integer overflow and underflow protections in library code, particularly in security-sensitive components that handle untrusted input data.