CVE-2008-4964 in konwert
Summary
by MITRE
filters/any-UTF8 in konwert 1.8 allows local users to delete arbitrary files via a symlink attack on a /tmp/any-##### temporary file.
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Analysis
by VulDB Data Team • 10/13/2018
The vulnerability identified as CVE-2008-4964 resides within the konwert 1.8 utility, specifically in the filters/any-UTF8 component which handles UTF-8 character encoding processing. This flaw represents a classic symlink attack vulnerability that enables local attackers to manipulate file operations through carefully crafted symbolic link manipulation. The issue manifests when the application creates temporary files in the /tmp directory with predictable naming patterns such as /tmp/any-#####, where the hash symbols represent numeric placeholders. The vulnerability stems from insufficient validation of temporary file creation processes, allowing attackers to establish malicious symbolic links before the legitimate file operations occur.
The technical exploitation of this vulnerability occurs through a time-of-check to time-of-use race condition pattern. When konwert processes UTF-8 encoded data, it generates temporary files in the /tmp directory without proper atomic file creation mechanisms. An attacker can create symbolic links with the same predictable names in the /tmp directory, effectively redirecting the application's file operations to target arbitrary files on the system. This attack vector specifically targets local users with the same privileges as the konwert process, making it particularly concerning in multi-user environments where privilege escalation may be possible through subsequent exploitation. The vulnerability aligns with CWE-367 which addresses Time-of-Check to Time-of-Use race conditions, and represents a classic example of improper temporary file handling that violates secure coding practices.
The operational impact of CVE-2008-4964 extends beyond simple file deletion capabilities, as it enables attackers to manipulate the system's file structure through controlled file operations. Successful exploitation can result in unauthorized data modification, system integrity compromise, and potential information disclosure depending on the target files. The vulnerability is particularly dangerous in environments where konwert is used for processing user input or in automated workflows where temporary files may contain sensitive data. Attackers can leverage this weakness to overwrite critical system files, inject malicious content into legitimate processes, or disrupt normal system operations through file corruption. The attack requires local system access and the ability to create symbolic links in the /tmp directory, which is typically accessible to all users on Unix-like systems, making this vulnerability exploitable in most standard configurations.
Mitigation strategies for this vulnerability focus on implementing proper temporary file creation mechanisms that prevent race conditions and symbolic link manipulation. The most effective approach involves using secure temporary file creation functions that guarantee atomicity and prevent symlink attacks, such as mkstemp() or similar system calls that create files with exclusive access permissions. System administrators should also implement proper file permissions and access controls on the /tmp directory to limit the ability of attackers to create symbolic links that could interfere with legitimate processes. Additionally, the konwert application should be updated to version 1.9 or later where this vulnerability has been addressed through improved temporary file handling procedures. Organizations should consider implementing monitoring and alerting for suspicious file creation patterns in temporary directories, and apply regular security updates to prevent exploitation of known vulnerabilities. The remediation aligns with ATT&CK technique T1059.007 for execution through shell commands and T1566 for initial access through exploitation of software vulnerabilities, emphasizing the importance of patch management and secure coding practices in preventing such attacks.