CVE-2005-2240 in xpvm
Summary
by MITRE
xpvm.tcl in xpvm 1.2.5 allows local users to overwrite arbitrary files via a symlink attack on the xpvm.trace.$user temporary file.
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Analysis
by VulDB Data Team • 07/09/2019
The vulnerability identified as CVE-2005-2240 affects the xpvm 1.2.5 software package and represents a classic file system race condition exploit that enables local privilege escalation through symbolic link manipulation. This flaw specifically targets the xpvm.tcl script which creates temporary files using predictable naming conventions without proper security checks. The vulnerability occurs when the application generates a temporary file named xpvm.trace.$user where $user represents the current user identifier, creating a predictable path that can be exploited by malicious local users.
The technical implementation of this vulnerability stems from improper temporary file handling practices that violate fundamental security principles. When xpvm.tcl executes, it creates a temporary file in a predictable location without sufficient access control measures or atomic file creation mechanisms. Local attackers can exploit this by creating symbolic links with the same names as the expected temporary files before the legitimate application creates them. This symlink attack allows the attacker to redirect the application's write operations to arbitrary locations on the file system, potentially overwriting critical system files or configuration data.
This vulnerability operates under the broader category of insecure temporary file handling as classified by CWE-377, specifically CWE-378 which addresses the creation of temporary files with insecure permissions. The attack vector leverages the principle of least privilege violation, where the application assumes that temporary files will be created securely without considering potential interference from malicious users. The operational impact extends beyond simple file overwrites to potentially enable privilege escalation scenarios where attackers can manipulate system-critical files to gain elevated privileges or disrupt normal system operations.
The attack requires local system access and involves a timing window where the attacker must establish symbolic links before the legitimate application creates its temporary files. This race condition approach aligns with ATT&CK technique T1059.001 for command and scripting interpreter and T1068 for local privilege escalation. The vulnerability demonstrates poor input validation and inadequate security measures in temporary file creation processes, which are common patterns in legacy software implementations from that era. Organizations with systems running affected versions of xpvm should immediately implement mitigations including proper temporary file handling with secure permissions, atomic file creation mechanisms, and regular security audits to identify similar vulnerabilities in other applications.
Mitigation strategies should focus on implementing proper temporary file security measures such as creating temporary files with unique names, using secure directory permissions, and employing atomic file creation techniques to prevent symbolic link attacks. System administrators should also consider upgrading to patched versions of xpvm or implementing additional access controls to limit local user privileges. The vulnerability highlights the importance of following secure coding practices and proper file system access control mechanisms as outlined in various security frameworks and standards that emphasize the need for robust temporary file handling in application development processes.