CVE-2022-0529 in unzip
Summary
by MITRE • 02/10/2022
A flaw was found in unzip 6.0. The vulnerability occurs during the conversion of wide string to local string that leads to a heap of out-of-bound writes. This flaw allows an attacker to input a specially crafted zip file, leading to a crash or code execution.
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Analysis
by VulDB Data Team • 05/01/2025
The vulnerability identified as CVE-2022-0529 represents a critical heap-based buffer overflow in the unzip utility version 6.0, specifically manifesting during wide string to local string conversion processes. This flaw exists within the decompression functionality of the unzip command-line tool, which is widely used across various operating systems and environments for extracting compressed archive files. The issue stems from improper handling of character encoding conversions where wide character strings containing Unicode data are processed without adequate bounds checking when converted to local character representations. The vulnerability is particularly concerning because it affects a fundamental system utility that is present in most Unix-like systems, Windows environments, and various embedded systems that utilize standard unzip implementations. Attackers can exploit this weakness by crafting malicious zip files containing specially formatted wide character sequences that trigger the overflow condition during extraction operations.
The technical exploitation of CVE-2022-0529 occurs when the unzip utility processes a malformed zip archive containing oversized or improperly encoded wide character data within file names or metadata structures. During the conversion process from wide character strings to local character strings, the software fails to validate the length of the source data against the destination buffer capacity, resulting in memory corruption through out-of-bounds writes. This memory corruption can overwrite adjacent heap memory regions, potentially leading to arbitrary code execution or application crashes. The vulnerability is classified as a heap buffer overflow according to CWE-122, which specifically addresses heap-based buffer overflow conditions that occur when more data is written to a heap buffer than it can hold. The flaw demonstrates characteristics consistent with CWE-787, which covers out-of-bounds writes in heap memory, making it particularly dangerous in environments where unzip is used with untrusted input from network sources or user-provided archives.
The operational impact of this vulnerability extends across multiple attack vectors and system environments where unzip is deployed, including web servers processing user uploads, automated build systems handling third-party libraries, and enterprise environments managing compressed software distributions. An attacker could craft a malicious zip file that, when processed by unzip, would cause the target system to execute arbitrary code with the privileges of the user running the unzip command. This could lead to complete system compromise, especially when unzip is executed with elevated privileges or in automated contexts. The vulnerability also poses risks in network-based attacks where malicious archives are delivered through email attachments, web downloads, or file sharing systems. According to ATT&CK framework, this vulnerability maps to T1059.007 for command and scripting interpreter and T1203 for Exploitation for Client Execution, as it enables attackers to execute code through compromised archive processing. The widespread availability of unzip across different platforms and its common usage in automated workflows amplifies the potential attack surface significantly.
Mitigation strategies for CVE-2022-0529 should prioritize immediate patching of unzip installations to versions that contain proper bounds checking and memory validation during string conversion operations. System administrators should implement strict input validation for all archive files processed through unzip, particularly those from untrusted sources or automated systems. The principle of least privilege should be enforced by running unzip with minimal required permissions and avoiding execution with elevated privileges. Network-level protections including web application firewalls and content filtering systems can help detect and block malicious zip files before they reach systems that process them. Additionally, organizations should consider implementing sandboxed environments for archive processing and regular security scanning of compressed files using updated antivirus and malware detection tools. The vulnerability highlights the importance of proper memory management practices and input validation in security-critical system utilities, emphasizing the need for regular security assessments of commonly used open source tools that form integral parts of system infrastructure.