CVE-2016-10374 in perltidy
Summary
by MITRE
perltidy through 20160302, as used by perlcritic, check-all-the-things, and other software, relies on the current working directory for certain output files and does not have a symlink-attack protection mechanism, which allows local users to overwrite arbitrary files by creating a symlink, as demonstrated by creating a perltidy.ERR symlink that the victim cannot delete.
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Analysis
by VulDB Data Team • 10/19/2024
The vulnerability identified as CVE-2016-10374 affects perltidy versions through 20160302, a Perl source code formatter widely used in development environments and automated tooling such as perlcritic and check-all-the-things. This flaw represents a classic symlink attack scenario where the tool operates without proper security controls when handling temporary or output files. The vulnerability stems from perltidy's reliance on the current working directory for generating certain output files, particularly the perltidy.ERR file used for error reporting. When perltidy processes Perl source files, it creates these output files in the directory from which it was invoked, making it susceptible to manipulation by malicious actors who can exploit this behavior to overwrite arbitrary files on the system.
The technical nature of this vulnerability aligns with CWE-376, which describes improper handling of symlinks in file operations, and CWE-275, which addresses permission problems in file operations. The flaw operates through a symlink attack mechanism where an attacker creates a symbolic link named perltidy.ERR in a directory where perltidy will be executed. When perltidy runs and attempts to write to this file, it follows the symlink and writes to the target file specified by the symlink rather than the intended location. This attack vector is particularly dangerous because it allows an attacker to overwrite files that the victim process cannot delete, effectively bypassing normal file permission controls and creating a persistent attack surface.
The operational impact of this vulnerability extends beyond simple file overwrite scenarios, as it can be exploited in various contexts where perltidy is used in automated workflows or development environments. Attackers can leverage this vulnerability to overwrite critical system files, configuration files, or even source code files, potentially leading to privilege escalation or persistent backdoors. The vulnerability is particularly concerning in continuous integration environments or automated code review systems where perltidy is invoked with elevated privileges or in shared development environments where multiple users have access to the same working directories. The attack requires minimal privileges and can be executed by any user who has write access to the directory where perltidy will be invoked, making it a significant concern for software development toolchains that process untrusted code.
Mitigation strategies for CVE-2016-10374 should focus on both immediate patching and operational security improvements. The most effective solution is to upgrade to perltidy version 20160303 or later, which includes proper symlink protection mechanisms. Organizations should also implement secure working directory practices, such as using temporary directories with restricted permissions for tool execution, and ensuring that development tools do not operate with elevated privileges when processing untrusted input. The ATT&CK framework categorizes this vulnerability under T1059.007 for execution through scripting and T1566 for social engineering attacks that could leverage this weakness. Additionally, implementing proper input validation and file operation security controls in automated tooling can prevent similar vulnerabilities from being exploited in other tools that may have similar design flaws. Regular security audits of development toolchains and automated processes should include checks for similar symlink attack vulnerabilities to ensure comprehensive protection against this class of attack.