CVE-2022-28506: Giflib Buffer Overflow Vulnerability

CVE-2022-28506 Overview

A heap-buffer-overflow vulnerability exists in GIFLIB version 5.2.1, specifically in the DumpScreen2RGB() function located in gif2rgb.c at line 298, column 45. This memory corruption flaw occurs during the processing of GIF image files, potentially allowing attackers to read sensitive information from memory through a specially crafted GIF file.

Critical Impact

Attackers can exploit this heap-buffer-overflow to access sensitive information stored in memory by tricking users into processing malicious GIF files with the vulnerable gif2rgb utility.

Affected Products

• GIFLIB Project GIFLIB version 5.2.1
• Fedora Project Fedora 35
• Fedora Project Fedora 36

Discovery Timeline

• April 25, 2022 - CVE-2022-28506 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2022-28506

Vulnerability Analysis

The vulnerability is a heap-buffer-overflow (CWE-787: Out-of-bounds Write) that occurs within the DumpScreen2RGB() function of the GIFLIB library. This function is responsible for converting GIF image data to RGB format during image processing operations. The flaw manifests when the function processes image data without properly validating buffer boundaries, leading to an out-of-bounds memory access condition.

The vulnerability requires local access and user interaction to exploit. An attacker must convince a user to open or process a maliciously crafted GIF file using the vulnerable gif2rgb utility or any application that incorporates the affected GIFLIB library code path.

Root Cause

The root cause of this vulnerability lies in inadequate bounds checking within the DumpScreen2RGB() function. When processing GIF image data, the function fails to properly validate that memory access operations stay within allocated buffer boundaries. This allows reads beyond the allocated heap buffer when processing specially crafted GIF files with manipulated dimension or color table parameters.

Attack Vector

The attack vector for CVE-2022-28506 requires local access to the target system. An attacker must craft a malicious GIF file designed to trigger the heap-buffer-overflow condition. When a user processes this file using the gif2rgb utility or an application linked against the vulnerable GIFLIB version, the overflow occurs.

The exploitation scenario typically involves:

1. Crafting a GIF file with manipulated image dimensions or color data
2. Delivering the malicious file to the target user
3. Waiting for the user to process the file with the gif2rgb tool
4. The overflow allows reading sensitive data from adjacent heap memory

For technical details and a proof-of-concept, refer to the GitHub PoC Repository and the SourceForge Bug Report.

Detection Methods for CVE-2022-28506

Indicators of Compromise

• Unexpected crashes or abnormal termination of applications using GIFLIB when processing GIF files
• AddressSanitizer (ASAN) reports indicating heap-buffer-overflow in the DumpScreen2RGB function
• Memory access violations originating from gif2rgb.c line 298 in crash dumps
• Suspicious GIF files with unusual dimension values or malformed color table entries

Detection Strategies

• Deploy memory sanitization tools (ASAN, Valgrind) in development and testing environments to detect heap overflow attempts
• Monitor system logs for application crashes related to GIF file processing utilities
• Implement file integrity monitoring for GIFLIB library files to detect unauthorized modifications
• Use static analysis tools to identify applications linked against vulnerable GIFLIB versions

Monitoring Recommendations

• Configure crash reporting systems to alert on failures in applications using GIFLIB
• Establish baseline behavior for GIF processing applications and alert on deviations
• Monitor network traffic for delivery of potentially malicious GIF files
• Enable verbose logging for image processing applications in sensitive environments

How to Mitigate CVE-2022-28506

Immediate Actions Required

• Update GIFLIB to a patched version that addresses the heap-buffer-overflow in DumpScreen2RGB()
• Review and update all applications that statically link or bundle GIFLIB 5.2.1
• Restrict usage of the gif2rgb utility to trusted GIF files only
• Consider implementing application sandboxing for processes that handle untrusted image files

Patch Information

Fedora has released security updates addressing this vulnerability. Users of affected Fedora versions should apply the available patches through standard package management. For details, see the Fedora Package Announcement for Fedora 35 and the Fedora Package Announcement for Fedora 36.

Workarounds

• Avoid processing untrusted GIF files with the gif2rgb utility until patches are applied
• Implement input validation to reject GIF files with suspicious or malformed headers before processing
• Run GIF processing utilities in a sandboxed or containerized environment to limit potential impact
• Disable or remove the gif2rgb utility if not required for operational purposes

# Check installed GIFLIB version on Fedora
rpm -q giflib

# Update GIFLIB package on Fedora systems
sudo dnf update giflib

# Verify update was applied
rpm -q giflib