CVE-2008-4085 in plait
Summary
by MITRE
plaiter in Plait before 1.6 allows local users to overwrite arbitrary files via a symlink attack on (1) cut.$$, (2) head.$$, (3) awk.$$, and (4) ps.$$ temporary files in /tmp/.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 10/08/2018
The vulnerability identified as CVE-2008-4085 affects the plaiter utility within the Plait software suite prior to version 1.6. This represents a classic race condition and symlink attack scenario that exploits insecure temporary file handling practices. The vulnerability specifically targets four temporary files named cut.$$, head.$$, awk.$$, and ps.$$ which are created in the /tmp/ directory during the execution of plaiter operations. These temporary files are created with predictable names and are susceptible to symlink attacks due to insufficient security measures during their creation process. The flaw allows local attackers to manipulate the system's temporary file namespace by creating symbolic links that point to sensitive system files or directories, thereby enabling arbitrary file overwrites.
The technical implementation of this vulnerability stems from the improper handling of temporary files in a multi-user environment where the plaiter utility creates temporary files without adequate security checks. When plaiter executes and creates these temporary files, it does not verify whether the target file already exists or whether it is a symbolic link. This insecure practice violates fundamental security principles for temporary file management and creates a window of opportunity for privilege escalation attacks. The vulnerability is particularly dangerous because it operates in the /tmp/ directory, which is typically world-writable and accessible to all local users, making it an ideal target for such attacks. The race condition aspect of this vulnerability means that between the time when the temporary file is checked for existence and when it is actually used, an attacker can establish a symbolic link with the same name.
The operational impact of CVE-2008-4085 extends beyond simple file overwrites to potentially enable privilege escalation and system compromise. Since the vulnerable software operates with elevated privileges, local users who can manipulate these temporary files can redirect the output of system commands to arbitrary locations, potentially overwriting critical system files or configuration data. This type of vulnerability aligns with CWE-362, which describes race conditions, and CWE-367, which covers time-of-check to time-of-use vulnerabilities. The attack vector can be leveraged to gain unauthorized access to system resources, modify system behavior, or even establish persistent backdoors. The temporary files involved are commonly used in shell operations and system administration tasks, making their compromise particularly damaging to system integrity and security.
Mitigation strategies for this vulnerability require immediate patching of the plaiter utility to version 1.6 or later where the insecure temporary file creation practices have been corrected. System administrators should ensure that all affected systems are updated promptly and that proper file permissions are enforced on the /tmp/ directory. The fix typically involves implementing secure temporary file creation methods such as using mkstemp() or similar functions that create files with exclusive access and proper permissions. Additionally, implementing proper file ownership checks and using the O_EXCL flag during file creation can prevent symlink attacks. From an ATT&CK perspective, this vulnerability maps to T1059.007 for command and script injection, and T1548.002 for abuse of system privileges. Organizations should also consider implementing monitoring for unusual file system activity in the /tmp/ directory and conducting regular security assessments to identify similar insecure temporary file handling patterns in other applications.