CVE-2022-4883 in libXpm
Summary
by MITRE • 02/07/2023
A flaw was found in libXpm. When processing files with .Z or .gz extensions, the library calls external programs to compress and uncompress files, relying on the PATH environment variable to find these programs, which could allow a malicious user to execute other programs by manipulating the PATH environment variable.
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Analysis
by VulDB Data Team • 03/06/2023
The vulnerability identified as CVE-2022-4883 resides within the libXpm library, a component commonly used in X Window System applications for handling X PixMap image files. This flaw represents a classic path traversal and command injection vulnerability that arises from the library's improper handling of compressed file extensions. When libXpm encounters files with .Z or .gz extensions, it automatically invokes external compression utilities such as gzip or compress to process these files, creating a direct dependency on system executables that are located through the PATH environment variable.
The technical implementation of this vulnerability stems from the library's design pattern where it relies on shell command execution without proper validation of the command paths. This behavior creates an exploitable condition where an attacker can manipulate the PATH environment variable to point to malicious executables with the same names as legitimate compression utilities. The flaw operates under CWE-78 principles, specifically addressing weak handling of external command execution and environment variable manipulation. When a user or application loads a specially crafted XPM file with compressed extensions, the library's internal logic executes shell commands without sanitizing the environment, thereby allowing arbitrary code execution as the privileges of the user running the application.
The operational impact of this vulnerability extends beyond simple privilege escalation scenarios as it affects any application that utilizes libXpm for image processing, particularly those in graphical environments such as desktop applications, development tools, and X11-based systems. Attackers can leverage this vulnerability to execute arbitrary commands on affected systems, potentially leading to complete system compromise. The attack vector is particularly concerning because it can be triggered through normal file operations, making it difficult to detect and prevent through traditional security measures. This vulnerability aligns with ATT&CK technique T1059.001 for command and scripting interpreter and T1566.001 for spearphishing attachments, as it enables attackers to execute malicious payloads through seemingly legitimate file processing operations.
Mitigation strategies for CVE-2022-4883 should focus on both immediate remediation and long-term architectural improvements. The most effective immediate solution involves updating to patched versions of libXpm where the library has been modified to either avoid external command execution entirely or to implement proper input validation and path sanitization. Organizations should also consider implementing environment variable restrictions, particularly limiting the PATH variable to contain only trusted directories, and employing privilege separation techniques for applications that process untrusted image files. Additionally, system administrators should monitor for unauthorized modifications to compression utilities and implement file integrity monitoring solutions to detect potential exploitation attempts. The vulnerability demonstrates the importance of following secure coding practices as outlined in the OWASP Secure Coding Guidelines, specifically addressing the principle of least privilege and input validation in external command execution scenarios.