CVE-2018-17828 in ZZIPlib
Summary
by MITRE
Directory traversal vulnerability in ZZIPlib 0.13.69 allows attackers to overwrite arbitrary files via a .. (dot dot) in a zip file, because of the function unzzip_cat in the bins/unzzipcat-mem.c file.
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Analysis
by VulDB Data Team • 07/10/2025
The vulnerability identified as CVE-2018-17828 represents a critical directory traversal flaw within ZZIPlib version 0.13.69 that exposes systems to arbitrary file overwrite attacks. This issue stems from inadequate input validation within the unzzip_cat function located in the bins/unzzipcat-mem.c source file, where the software fails to properly sanitize path references extracted from zip archives. The flaw specifically manifests when processing zip file entries containing .. (dot dot) sequences in their filenames, allowing malicious actors to manipulate the extraction path beyond the intended destination directory.
The technical implementation of this vulnerability leverages the fundamental weakness in path resolution logic where the application does not adequately check for directory traversal sequences in compressed file entries. When ZZIPlib processes a zip archive containing entries with .. components in their paths, the extraction routine fails to normalize or validate these paths against the target extraction directory, enabling attackers to specify arbitrary absolute or relative paths outside the intended extraction scope. This behavior directly violates security principles of path isolation and access control enforcement, creating a pathway for unauthorized file system modifications.
From an operational impact perspective, this vulnerability presents significant risks to systems that utilize ZZIPlib for processing untrusted zip files, particularly in web applications, file upload handlers, and automated processing environments. Attackers can exploit this weakness to overwrite critical system files, configuration data, or even executable components, potentially leading to complete system compromise. The vulnerability is particularly dangerous in environments where zip file processing occurs with elevated privileges, as it could enable privilege escalation attacks. Additionally, the impact extends beyond simple file overwrites to include potential denial of service scenarios where critical system files are corrupted or deleted.
The security implications of CVE-2018-17828 align with CWE-22, which specifically addresses improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. This classification indicates that the vulnerability represents a well-established pattern of security flaws in file system access controls that have been documented across numerous software platforms. The ATT&CK framework categorizes this type of vulnerability under T1059 (Command and Scripting Interpreter) and T1074 (Data Staged) as attackers can leverage such weaknesses to execute malicious code or stage further attacks through compromised files. Organizations using ZZIPlib in production environments should implement immediate mitigations including input validation, path normalization, and privilege restriction measures to prevent exploitation of this directory traversal vulnerability.
Mitigation strategies for CVE-2018-17828 should focus on implementing comprehensive path validation and sanitization mechanisms within applications that process zip files. System administrators should ensure that ZZIPlib is updated to versions that address this vulnerability, while developers should implement strict file path validation that rejects any entries containing .. sequences or absolute paths. Additional protective measures include running file processing applications with minimal required privileges, implementing proper directory isolation, and deploying intrusion detection systems that monitor for suspicious file system access patterns. Organizations should also conduct thorough code reviews to identify similar vulnerabilities in other libraries and applications that may be susceptible to the same class of path traversal attacks.