CVE-2022-0529: Unzip Heap Overflow RCE Vulnerability

CVE-2022-0529 Overview

A heap out-of-bounds write vulnerability has been discovered in Unzip, the popular archive extraction utility. The flaw occurs during the conversion of a wide string to a local string, resulting in a heap out-of-bound write condition. This vulnerability allows an attacker to craft a specially designed zip file that, when processed by a vulnerable version of Unzip, can lead to application crashes or potentially arbitrary code execution.

Critical Impact
Attackers can exploit this vulnerability by distributing malicious zip files that trigger heap corruption when extracted, potentially allowing code execution on the target system.

Affected Products

Unzip Project Unzip 6.0
Red Hat Enterprise Linux 8.0
Fedora 35
Debian Linux 10.0 and 11.0

Discovery Timeline

February 9, 2022 - CVE-2022-0529 published to NVD
November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2022-0529

Vulnerability Analysis

This vulnerability is classified as CWE-787 (Out-of-bounds Write), a memory corruption issue that occurs when software writes data past the end, or before the beginning, of an allocated memory buffer. In the case of CVE-2022-0529, the flaw manifests during character encoding conversion operations within Unzip.

The vulnerability requires local access and user interaction to exploit, as the victim must process a maliciously crafted zip archive. While the attack complexity is low, the impact is primarily limited to availability concerns, causing denial of service through application crashes. However, in certain scenarios, the heap corruption could potentially be leveraged for code execution.

Root Cause

The root cause lies in improper bounds checking during the wide string to local string conversion process in Unzip. When processing filenames or other string data within zip archives, the application fails to properly validate the size of the destination buffer before writing converted character data. This allows an attacker to craft archive entries with specially formatted strings that overflow the allocated heap buffer during the conversion process.

Attack Vector

The attack vector is local, requiring an attacker to deliver a malicious zip file to the target system. The exploitation scenario typically involves:

An attacker creates a specially crafted zip archive containing malformed string data designed to trigger the out-of-bounds write
The victim downloads or receives the malicious archive through email, file sharing, or other delivery mechanisms
When the victim extracts the archive using a vulnerable version of Unzip, the wide-to-local string conversion triggers the heap overflow
The resulting memory corruption causes the application to crash, and under specific conditions, may allow code execution

Technical details and proof-of-concept materials are available in the GitHub PoC Repository. Additional technical analysis can be found in the Red Hat Bug Report #2051395.

Detection Methods for CVE-2022-0529

Indicators of Compromise

Unexpected crashes of the unzip binary when processing archive files
Core dumps or crash reports indicating heap corruption in the unzip process
Suspicious zip files with unusually long or malformed filenames containing non-ASCII characters
Segmentation faults during archive extraction operations

Detection Strategies

Monitor system logs for unzip process crashes and segmentation faults
Implement file integrity monitoring to detect unauthorized changes to the unzip binary
Deploy endpoint detection solutions like SentinelOne to identify exploitation attempts targeting memory corruption vulnerabilities
Scan inbound archives at email and web gateways for known exploit patterns

Monitoring Recommendations

Enable crash reporting and core dump collection for forensic analysis
Monitor for unusual unzip process behavior including unexpected termination or memory access violations
Implement alerting for multiple failed archive extraction attempts from the same source
Review audit logs for archive extraction activities, particularly from untrusted sources

How to Mitigate CVE-2022-0529

Immediate Actions Required

Update Unzip to the latest patched version available from your distribution
Restrict the use of unzip to trusted archive files from verified sources
Implement user awareness training about the risks of extracting untrusted archives
Consider using alternative archive tools with stronger security validation while awaiting patches

Patch Information

Security patches are available from multiple Linux distributions. Administrators should apply updates from the following advisories:

For Red Hat Enterprise Linux systems, check the Red Hat Bug Report #2051395 for patch availability and deployment guidance.

Workarounds

Use alternative archive extraction tools such as 7z or p7zip that are not affected by this vulnerability
Implement strict file validation policies for incoming archives before extraction
Run unzip operations in sandboxed or containerized environments to limit potential damage
Configure file access controls to limit which users can execute the unzip binary

bash

# Configuration example
# Check current unzip version
unzip -v

# Update unzip on Debian/Ubuntu systems
sudo apt update && sudo apt upgrade unzip

# Update unzip on RHEL/CentOS systems
sudo yum update unzip

# Update unzip on Fedora systems
sudo dnf update unzip