CVE-2010-0831 in FastJar
Summary
by MITRE
Directory traversal vulnerability in the extract_jar function in jartool.c in FastJar 0.98 allows remote attackers to create or overwrite arbitrary files via a .. (dot dot) in a non-initial pathname component in a filename within a .jar archive, a related issue to CVE-2005-1080. NOTE: this vulnerability exists because of an incomplete fix for CVE-2006-3619.
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Analysis
by VulDB Data Team • 09/18/2021
The vulnerability described in CVE-2010-0831 represents a critical directory traversal flaw within the FastJar 0.98 utility's jartool.c component. This security issue specifically affects the extract_jar function which processes jar archive files and demonstrates how incomplete security patches can leave systems vulnerable to exploitation. The flaw enables remote attackers to manipulate file system operations by leveraging directory traversal sequences within jar archive contents, creating a significant risk for systems that process untrusted jar files without proper validation.
The technical implementation of this vulnerability stems from insufficient input validation within the jar extraction process. When processing filenames within jar archives, the extract_jar function fails to properly sanitize pathname components that contain .. sequences, particularly when these sequences appear in non-initial positions within file paths. This allows attackers to craft malicious jar files containing filenames such as "path/../evilfile" which, when extracted, can write files to arbitrary locations on the target system. The vulnerability specifically targets the handling of pathname components where directory traversal sequences are not properly detected and neutralized during the extraction process.
The operational impact of this vulnerability extends beyond simple file creation or overwriting operations, as it enables attackers to potentially compromise system integrity and availability. An attacker could leverage this weakness to overwrite critical system files, inject malicious code into existing applications, or create backdoor access points within the target environment. The remote exploitation capability means that systems processing jar files from untrusted sources are at risk, making this vulnerability particularly dangerous in web applications, automated build systems, or any environment where jar archives are automatically extracted without proper security controls. This vulnerability directly relates to the common weakness identified in CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as directory traversal or path traversal attacks.
The vulnerability exists because of an incomplete fix for CVE-2006-3619, demonstrating how security remediation efforts can be insufficient when not properly addressing all potential attack vectors. This incomplete patching approach leaves systems vulnerable to similar exploitation patterns, as the original security issue was not fully resolved. The connection to CVE-2005-1080 further illustrates how directory traversal vulnerabilities can persist across multiple versions of software when security updates fail to comprehensively address the root cause. Organizations using FastJar 0.98 or similar jar processing utilities should recognize this vulnerability as part of a broader category of path traversal issues that can compromise system security and data integrity.
Mitigation strategies for this vulnerability require immediate attention and comprehensive system hardening measures. Organizations should prioritize updating to patched versions of FastJar or implementing strict input validation controls that prevent extraction of files with potentially dangerous pathname sequences. Security controls should include mandatory validation of all jar file contents, implementation of secure extraction practices that reject or sanitize potentially malicious path components, and deployment of network-based protections such as web application firewalls that can detect and block malicious jar file processing attempts. The ATT&CK framework categorizes this type of vulnerability under privilege escalation and defense evasion techniques, emphasizing the need for layered security approaches that prevent both initial exploitation and subsequent malicious activity within compromised systems.