CVE-2022-31782: FreeType Demo Buffer Overflow Flaw

CVE-2022-31782 Overview

CVE-2022-31782 is a heap-based buffer overflow vulnerability in ftbench.c within FreeType Demo Programs through version 2.12.1. This memory corruption vulnerability allows attackers to potentially execute arbitrary code or cause a denial of service by exploiting improper memory handling during font benchmarking operations.

Critical Impact
A heap-based buffer overflow in FreeType Demo Programs can lead to arbitrary code execution, memory corruption, or application crashes when processing maliciously crafted input.

Affected Products

FreeType Demo Programs versions through 2.12.1
Freedesktop FreeType Demo Programs (all affected versions)
Systems utilizing ftbench utility from the FreeType Demo Programs package

Discovery Timeline

2022-06-02 - CVE CVE-2022-31782 published to NVD
2024-11-21 - Last updated in NVD database

Technical Details for CVE-2022-31782

Vulnerability Analysis

This vulnerability is classified as CWE-787 (Out-of-bounds Write), manifesting as a heap-based buffer overflow in the ftbench.c source file. The vulnerability exists within the FreeType Demo Programs package, which provides various utilities for testing and benchmarking FreeType font rendering capabilities.

The heap-based buffer overflow occurs when the ftbench utility processes input without proper bounds checking, allowing data to be written beyond the allocated heap buffer boundaries. This type of memory corruption can lead to application crashes, corruption of heap metadata, and potentially enable attackers to gain control of program execution flow.

The attack requires local access and user interaction, meaning an attacker must either have local system access or convince a user to process a malicious file with the vulnerable ftbench utility. Successful exploitation can result in complete compromise of confidentiality, integrity, and availability of the affected system.

Root Cause

The root cause of CVE-2022-31782 is improper bounds checking in the ftbench.c source file when handling input data. The vulnerability stems from insufficient validation of buffer sizes during memory operations, allowing write operations to exceed the allocated heap buffer boundaries. This is a classic heap overflow pattern where the application fails to verify that incoming data fits within the pre-allocated memory region.

Attack Vector

The attack vector for this vulnerability requires local access to the target system. An attacker must craft malicious input that triggers the heap-based buffer overflow when processed by the ftbench utility. The exploitation scenario typically involves:

The attacker creates a specially crafted input file designed to trigger the overflow condition
The victim runs the ftbench utility against the malicious input
The overflow corrupts heap memory, potentially allowing the attacker to overwrite critical data structures or function pointers
Successful exploitation can lead to arbitrary code execution within the context of the running process

The vulnerability requires no special privileges to exploit, though user interaction is necessary to trigger the vulnerable code path. Technical details regarding the specific exploitation mechanism can be found in the GitLab Issue Discussion.

Detection Methods for CVE-2022-31782

Indicators of Compromise

Unexpected crashes or segmentation faults when running the ftbench utility
Memory corruption errors or heap-related warnings in system logs
Unusual process behavior or unexpected child process spawning from ftbench
Core dump files generated by the ftbench process

Detection Strategies

Monitor for execution of ftbench with unusual or untrusted input files
Implement application whitelisting to control which utilities can be executed
Deploy memory protection tools such as AddressSanitizer (ASan) to detect heap overflows at runtime
Audit systems for the presence of vulnerable FreeType Demo Programs versions (through 2.12.1)

Monitoring Recommendations

Enable heap memory monitoring and corruption detection in development and testing environments
Configure system auditing to log execution of FreeType Demo Programs utilities
Implement file integrity monitoring on directories containing FreeType binaries
Set up alerts for crash events associated with ftbench or related FreeType utilities

How to Mitigate CVE-2022-31782

Immediate Actions Required

Update FreeType Demo Programs to a version newer than 2.12.1 that contains the security fix
Restrict access to the ftbench utility to only trusted users who require it for legitimate purposes
Avoid processing untrusted font files or input with the vulnerable utility
Consider removing FreeType Demo Programs if not required for production operations

Patch Information

The vulnerability was reported and tracked through the FreeType Demos GitLab repository. Users should update to the latest version of FreeType Demo Programs that addresses this heap-based buffer overflow. Consult the FreeType project's official releases for patched versions containing the security fix.

Workarounds

Isolate systems running FreeType Demo Programs from untrusted networks and input sources
Run the ftbench utility in a sandboxed environment or container with restricted privileges
Implement strict input validation for any files processed by FreeType utilities
Use operating system-level protections such as ASLR and DEP/NX to mitigate exploitation

bash

# Verify installed FreeType Demo Programs version
ftbench --version

# Check for vulnerable package on Debian/Ubuntu systems
dpkg -l | grep freetype | grep demo

# Remove FreeType Demo Programs if not needed
sudo apt-get remove freetype2-demos