CVE-2008-4949 in dist
Summary
by MITRE
dist 3.5 allows local users to overwrite arbitrary files via a symlink attack on (a) /tmp/cil#####, (b) /tmp/pdo#####, and (c) /tmp/pdn##### temporary files, related to the (1) patcil and (2) patdiff scripts.
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Analysis
by VulDB Data Team • 10/13/2018
The vulnerability described in CVE-2008-4949 represents a critical security flaw in the dist 3.5 software package that enables local attackers to perform arbitrary file overwrite operations through symbolic link attacks. This issue specifically targets temporary files created during the execution of patcil and patdiff scripts, which are part of the distribution management utilities. The vulnerability stems from improper handling of temporary file creation processes that do not adequately validate the existence or ownership of target locations before writing data to them.
The technical implementation of this flaw involves the creation of temporary files using predictable naming patterns such as /tmp/cil#####, /tmp/pdo#####, and /tmp/pdn##### where the hash characters represent numeric sequences. When the affected scripts execute, they create these temporary files in the /tmp directory without proper security checks that would prevent malicious users from establishing symbolic links with the same names before the legitimate scripts attempt to create them. This race condition scenario allows attackers to control what files are written to during the execution process, potentially enabling them to overwrite critical system files or inject malicious content into legitimate program data.
From an operational impact perspective, this vulnerability poses significant risks to systems running affected versions of the dist package, particularly in multi-user environments where local privilege escalation opportunities exist. The ability to overwrite arbitrary files through symlink manipulation can lead to persistent backdoors, data corruption, or complete system compromise depending on which files are targeted. Attackers could potentially overwrite configuration files, binaries, or system libraries to gain elevated privileges or maintain unauthorized access to the compromised system. The vulnerability affects the integrity and confidentiality of the system by enabling unauthorized modifications to critical components.
The flaw aligns with CWE-377: Insecure Temporary Files and CWE-378: Creation of Temporary Files With Insecure Permissions, both of which are categorized under insecure programming practices that create opportunities for attackers to manipulate temporary file operations. This vulnerability also maps to ATT&CK technique T1059.007: Command and Scripting Interpreter: Unix Shell, as attackers may leverage these temporary file overwrites to establish persistent access or execute malicious commands through compromised system components. The attack vector demonstrates a classic privilege escalation pattern where local users can exploit inadequate file permission handling to modify system resources.
Mitigation strategies should focus on implementing proper temporary file handling practices that include using secure temporary file creation functions, validating file ownership and permissions before writing, and avoiding predictable naming patterns for temporary files. System administrators should immediately apply patches or updates provided by the software vendor, ensure proper file permissions are enforced on the /tmp directory, and implement monitoring for suspicious temporary file creation activities. Additionally, organizations should consider implementing mandatory access controls and file integrity monitoring solutions to detect unauthorized modifications to critical system files that could result from exploitation of this vulnerability. The recommended approach involves upgrading to patched versions of the dist package and implementing secure coding practices that prevent race conditions in temporary file operations.