CVE-2011-4114 in Par-packer Module
Summary
by MITRE
The par_mktmpdir function in the PAR::Packer module before 1.012 for Perl creates temporary files in a directory with a predictable name without verifying ownership and permissions of this directory, which allows local users to overwrite files when another user extracts a PAR packed program. NOTE: a similar vulnerability was reported for PAR, but this has been assigned a different CVE identifier.
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Analysis
by VulDB Data Team • 11/28/2021
The vulnerability identified as CVE-2011-4114 resides within the PAR::Packer Perl module, specifically in the par_mktmpdir function that handles temporary file creation during program extraction processes. This flaw represents a classic path traversal and file overwrite vulnerability that exploits predictable temporary directory naming conventions to enable unauthorized file manipulation. The vulnerability affects versions prior to 1.012 of the PAR::Packer module, making it a significant concern for systems that rely on PAR packed executables for distribution and execution.
The technical implementation of this vulnerability stems from the par_mktmpdir function's failure to properly validate directory ownership and permissions before creating temporary files. When a PAR packed program is extracted, the module generates temporary directories using predictable naming patterns that do not adequately randomize or secure the directory structure. This predictable naming scheme allows local users to anticipate and manipulate the temporary directory locations, creating conditions where they can overwrite files owned by other users during the extraction process. The flaw operates under the principle of insecure temporary file creation, where the lack of proper access control verification creates a window of opportunity for privilege escalation and file manipulation attacks.
From an operational impact perspective, this vulnerability enables local privilege escalation and arbitrary file overwrite scenarios that can have severe consequences for system security. When another user extracts a PAR packed program on a compromised system, the malicious local user can exploit the predictable temporary directory creation to overwrite files with malicious content, potentially leading to code execution, data corruption, or unauthorized access to sensitive information. The vulnerability affects systems where multiple users share the same machine and where PAR packed programs are regularly extracted, making it particularly dangerous in multi-user environments, shared hosting scenarios, or development environments where different users might execute PAR packed applications.
The vulnerability aligns with CWE-377 and CWE-378 categories, specifically addressing weaknesses in insecure temporary file creation and predictable temporary directory names. It also maps to ATT&CK technique T1059.007 for execution through Perl scripting and T1078 for valid accounts usage, as it exploits legitimate user privileges to perform unauthorized file operations. Organizations should implement immediate mitigations including upgrading to PAR::Packer version 1.012 or later, which includes proper temporary directory validation and secure randomization of temporary file locations. Additionally, system administrators should review and harden temporary directory permissions, implement proper file ownership verification, and consider network segmentation to limit the potential impact of such vulnerabilities. Regular security audits and dependency management practices should be enforced to prevent similar issues in other modules and applications that might employ similar temporary file creation patterns.