CVE-2023-3576: Libtiff Memory Leak DOS Vulnerability

CVE-2023-3576 Overview

A memory leak flaw was found in Libtiff's tiffcrop utility. This issue occurs when tiffcrop operates on a TIFF image file, allowing an attacker to pass a crafted TIFF image file to the tiffcrop utility, which causes this memory leak issue, resulting in an application crash and eventually leading to a denial of service.

Critical Impact

This memory leak vulnerability in Libtiff's tiffcrop utility can be exploited through specially crafted TIFF image files to cause application crashes and denial of service conditions on affected systems.

Affected Products

• Libtiff libtiff (all versions prior to patch)
• Fedora (Fedoraproject)
• Red Hat Enterprise Linux 8.0 and 9.0

Discovery Timeline

• 2023-10-04 - CVE-2023-3576 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-3576

Vulnerability Analysis

This vulnerability is classified under CWE-401 (Missing Release of Memory after Effective Lifetime) and CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The flaw resides in Libtiff's tiffcrop utility, a command-line tool used for extracting sections from TIFF image files.

When processing maliciously crafted TIFF image files, the tiffcrop utility fails to properly release allocated memory resources. This improper memory management leads to a progressive memory leak that accumulates over time or during repeated processing operations. The vulnerability requires local access and user interaction to exploit, as an attacker must convince a user to process a malicious TIFF file using the vulnerable utility.

Root Cause

The root cause stems from improper memory management in the tiffcrop utility's TIFF file processing routines. Specifically, memory allocated during image parsing and manipulation operations is not properly freed after use, leading to memory exhaustion over extended operation periods. This falls under CWE-401 (Missing Release of Memory after Effective Lifetime), where dynamically allocated memory is not deallocated after it is no longer needed.

Attack Vector

The attack vector is local, requiring an attacker to deliver a specially crafted TIFF image file to a target user. The attack scenario involves:

1. An attacker creates a malicious TIFF file designed to trigger the memory leak condition
2. The crafted file is delivered to a victim through various means (email attachment, file sharing, etc.)
3. When the victim processes the malicious TIFF file using the tiffcrop utility, memory is allocated but not properly released
4. Repeated processing or processing of multiple crafted files leads to memory exhaustion
5. The application eventually crashes due to resource exhaustion, causing denial of service

The vulnerability requires user interaction as the victim must actively process the malicious file with the vulnerable utility. No remote exploitation path exists without this user action.

Detection Methods for CVE-2023-3576

Indicators of Compromise

• Abnormally high memory consumption by tiffcrop processes during TIFF file operations
• Unexpected crashes of the tiffcrop utility when processing TIFF image files
• System memory exhaustion events correlated with TIFF processing activities
• Presence of suspicious or malformed TIFF files from untrusted sources

Detection Strategies

• Monitor memory usage patterns of tiffcrop processes for unusual growth patterns
• Implement file integrity monitoring for TIFF files in processing directories
• Deploy endpoint detection rules to identify abnormal memory allocation behaviors in Libtiff utilities
• Use application-level monitoring to detect repeated crashes of image processing tools

Monitoring Recommendations

• Configure system resource monitoring to alert on abnormal memory consumption by image processing utilities
• Implement logging for all tiffcrop utility invocations and their exit statuses
• Monitor for core dumps or crash reports associated with Libtiff utilities
• Set up alerting for out-of-memory conditions in systems that regularly process TIFF images

How to Mitigate CVE-2023-3576

Immediate Actions Required

• Update Libtiff to the latest patched version available from your distribution's package repository
• Restrict access to tiffcrop utility to trusted users only until patching is complete
• Implement input validation to screen TIFF files before processing with vulnerable utilities
• Consider using alternative TIFF processing tools while awaiting patches

Patch Information

Red Hat has released security updates addressing this vulnerability. Refer to Red Hat Security Advisory RHSA-2023:6575 for patching instructions specific to Red Hat Enterprise Linux 8.0 and 9.0. Additional information is available in the Red Hat CVE-2023-3576 Information page and Red Hat Bug #2219340 Report. Debian users should consult the Debian LTS Announcement March 2024 for applicable updates.

Workarounds

• Avoid processing TIFF files from untrusted or unknown sources until systems are patched
• Implement resource limits (ulimit) on processes running tiffcrop to prevent system-wide memory exhaustion
• Use containerization or sandboxing for TIFF processing operations to isolate memory consumption
• Consider converting TIFF files to other formats using alternative tools before processing

# Example: Set memory limits for tiffcrop processes
# Limit process to 512MB of memory
ulimit -v 524288
tiffcrop input.tiff output.tiff

# Alternative: Run tiffcrop in a restricted cgroup
# Create memory-limited cgroup and run tiffcrop within it
cgcreate -g memory:/tiffcrop_limited
echo 536870912 > /sys/fs/cgroup/memory/tiffcrop_limited/memory.limit_in_bytes
cgexec -g memory:tiffcrop_limited tiffcrop input.tiff output.tiff