CVE-2018-1002201 in zt-zip
Summary
by MITRE
zt-zip before 1.13 is vulnerable to directory traversal, allowing attackers to write to arbitrary files via a ../ (dot dot slash) in a Zip archive entry that is mishandled during extraction. This vulnerability is also known as 'Zip-Slip'.
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Analysis
by VulDB Data Team • 04/25/2023
The vulnerability identified as CVE-2018-1002201 affects the zt-zip library version 1.13 and earlier, presenting a critical directory traversal flaw that enables attackers to write files to arbitrary locations on the target system. This vulnerability manifests when the library improperly handles Zip archive entries containing ../ (dot dot slash) sequences during extraction processes, allowing malicious actors to bypass intended directory boundaries and overwrite critical system files or inject malicious content into unexpected locations. The issue is commonly referred to as 'Zip-Slip' due to its ability to slip past directory restrictions and traverse to unintended directories during file extraction operations.
The technical flaw resides in the improper validation of archive entry paths during decompression, where the zt-zip library fails to properly sanitize or canonicalize file paths before writing extracted content to disk. When a Zip archive contains entries with relative path traversal sequences such as ../..//../../../etc/passwd, the library processes these paths without adequate checks, resulting in the extraction of files to locations outside the intended target directory. This behavior directly violates security principles of path validation and access control, creating a pathway for unauthorized file system modifications. The vulnerability maps to CWE-22 Directory Traversal and aligns with ATT&CK technique T1059.007 for executing malicious code through file system manipulation, while also supporting T1078 for privilege escalation through file system compromise.
The operational impact of this vulnerability is severe and far-reaching, particularly in environments where automated file extraction processes are common such as web applications, build systems, container orchestration platforms, and automated deployment pipelines. Attackers can exploit this vulnerability to overwrite critical system binaries, inject malicious code into existing applications, or create backdoor access points by placing malicious files in system directories. In containerized environments, this vulnerability becomes particularly dangerous as it can enable attackers to escape container boundaries and compromise the host system. The vulnerability affects any system that relies on the zt-zip library for processing untrusted Zip archives, making it a widespread concern across numerous applications and platforms that handle file compression and decompression operations.
Mitigation strategies for this vulnerability require immediate patching of the zt-zip library to version 1.13 or later, which includes proper path validation and canonicalization routines. Organizations should implement comprehensive input validation for all file paths extracted from Zip archives, ensuring that all paths are normalized and checked against intended target directories before extraction occurs. Security measures should include implementing restrictive file permissions, deploying file system monitoring solutions, and establishing automated scanning for malicious archive content. Additionally, organizations should consider implementing sandboxing techniques for processing untrusted archives and regularly audit their codebases for similar path traversal vulnerabilities. The fix typically involves implementing proper path canonicalization that resolves all relative paths and rejects any entries that attempt to traverse above the intended extraction directory, effectively preventing the Zip-Slip attack vector.