CVE-2023-1916: Libtiff Denial of Service Vulnerability

CVE-2023-1916 Overview

A flaw was found in tiffcrop, a program distributed by the libtiff package. A specially crafted TIFF file can lead to an out-of-bounds read in the extractImageSection function in tools/tiffcrop.c, resulting in a denial of service and limited information disclosure. This issue affects libtiff versions 4.x.

Critical Impact

Processing a maliciously crafted TIFF file with tiffcrop can cause application crashes (denial of service) and potentially leak sensitive memory contents through information disclosure.

Affected Products

• libtiff 4.x versions
• Systems utilizing tiffcrop for TIFF image processing
• Applications depending on libtiff library (including Apple products per HT213844)

Discovery Timeline

• 2023-04-10 - CVE-2023-1916 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-1916

Vulnerability Analysis

This vulnerability is classified as CWE-125: Out-of-Bounds Read. The flaw exists in the extractImageSection function within tools/tiffcrop.c, which is part of the tiffcrop utility used for cropping and manipulating TIFF images. When processing a specially crafted TIFF file, the function fails to properly validate boundaries before reading image data, allowing an attacker to cause the program to read memory beyond the allocated buffer.

The local attack vector requires user interaction, as a victim must process a malicious TIFF file using tiffcrop. While exploitation does not require privileges, the attacker must convince a user to open or process the malicious file. The vulnerability primarily impacts availability through denial of service, with a secondary impact on confidentiality through limited information disclosure from leaked memory contents.

Root Cause

The root cause is insufficient boundary checking in the extractImageSection function. When parsing TIFF image sections, the code does not adequately validate that the requested image coordinates and dimensions fall within the bounds of the actual image data buffer. This allows crafted TIFF files with malformed section parameters to trigger reads beyond the allocated memory region.

Attack Vector

The attack requires local access and user interaction. An attacker must craft a malicious TIFF file with specially constructed image section parameters and deliver it to a victim. When the victim processes this file using tiffcrop or an application that utilizes the vulnerable libtiff functionality, the out-of-bounds read is triggered.

The exploitation scenario typically involves:

1. Attacker creates a malicious TIFF file with manipulated image section metadata
2. The file is delivered to the victim through email, web download, or file sharing
3. The victim processes the TIFF file using tiffcrop or a vulnerable application
4. The extractImageSection function reads beyond buffer boundaries
5. This results in application crash (DoS) or potential memory content leakage

For detailed technical analysis, refer to GitLab Issue #536 and GitLab Issue #537.

Detection Methods for CVE-2023-1916

Indicators of Compromise

• Unexpected crashes of tiffcrop or applications using libtiff when processing TIFF files
• Core dumps or crash logs indicating segmentation faults in extractImageSection or related functions
• Unusual TIFF files with malformed or suspicious image section metadata

Detection Strategies

• Monitor for abnormal termination of processes using libtiff components
• Implement file integrity monitoring for TIFF files processed in sensitive environments
• Deploy application-level monitoring to detect repeated crashes when processing image files
• Use memory sanitizers (ASan, MSan) in development/testing environments to catch out-of-bounds reads

Monitoring Recommendations

• Configure crash reporting to capture and analyze tiffcrop failures
• Implement input validation for TIFF files before processing in production workflows
• Monitor system logs for patterns of repeated image processing failures
• Deploy SentinelOne endpoint protection to detect exploitation attempts and anomalous process behavior

How to Mitigate CVE-2023-1916

Immediate Actions Required

• Update libtiff to the latest patched version available from your distribution
• Restrict use of tiffcrop to trusted TIFF files only
• Implement input validation for TIFF files from untrusted sources
• Consider sandboxing tiffcrop operations to limit potential impact

Patch Information

Users should update to a patched version of libtiff that addresses this vulnerability. Check your operating system's package manager for security updates to the libtiff package. Apple users should refer to the Apple Support Article HT213844 for relevant security updates.

For tracking and additional details, see GitLab Issue #536 and GitLab Issue #537.

Workarounds

• Avoid processing TIFF files from untrusted or unknown sources with tiffcrop
• Use alternative tools for TIFF manipulation until patching is complete
• Implement strict file type validation before processing image files
• Run tiffcrop in a sandboxed or containerized environment to limit impact of potential exploitation

# Example: Running tiffcrop in a restricted environment
# Using firejail to sandbox tiffcrop execution
firejail --private --net=none tiffcrop input.tiff output.tiff

# Check installed libtiff version
pkg-config --modversion libtiff