CVE-2002-0210 in BRU
Summary
by MITRE
setlicense for TOLIS Group Backup and Restore Utility (BRU) 17.0 allows local users to overwrite arbitrary files via a symlink attack on the /tmp/brutest.$$ temporary file.
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Analysis
by VulDB Data Team • 11/12/2024
The vulnerability described in CVE-2002-0210 represents a critical security flaw in the TOLIS Group Backup and Restore Utility version 17.0, specifically within its setlicense component. This issue manifests as a race condition vulnerability that enables local attackers to manipulate system files through symbolic link attacks against temporary file locations. The flaw occurs when the utility creates temporary files in the /tmp directory without proper security checks, making it susceptible to exploitation by malicious users who can establish symbolic links before the utility performs its file operations.
The technical implementation of this vulnerability stems from the improper handling of temporary files in a multi-user environment where the setlicense utility creates a temporary file named brutest.$$ in the /tmp directory. During the execution process, the utility does not verify whether the target temporary file already exists or whether it is a symbolic link pointing to another location. This creates a window of opportunity for attackers to pre-create symbolic links that redirect the utility's file operations to arbitrary locations on the filesystem, potentially allowing them to overwrite critical system files or inject malicious content into sensitive locations.
From an operational perspective, this vulnerability poses significant risks to system integrity and security posture, particularly in environments where the BRU utility is installed and used with elevated privileges. The local nature of the attack means that any user with access to the system can exploit this weakness, making it particularly dangerous in multi-user environments where privilege escalation is not required. The impact extends beyond simple file overwrites, as attackers could potentially compromise system stability, introduce backdoors, or gain unauthorized access to sensitive data through manipulation of backup and restore operations. This vulnerability directly relates to CWE-367, which addresses time-of-check to time-of-use race conditions, and aligns with ATT&CK technique T1059 for execution through system utilities, as the compromised utility becomes a vector for further attacks.
The exploitation of this vulnerability requires minimal privileges and can be executed through standard user-level access, making it particularly dangerous as it bypasses many traditional security controls. System administrators should consider implementing immediate mitigations such as restricting write permissions to the /tmp directory for non-root users, monitoring for suspicious symbolic link creation in temporary directories, and applying the vendor-provided patches or updates that address this specific race condition. Organizations should also conduct thorough audits of their backup and restore utilities to identify similar vulnerabilities in other software components, as this type of temporary file handling issue is commonly found in legacy applications and may indicate broader security weaknesses in system design practices. Additionally, implementing proper file system permissions and using more secure temporary file creation methods such as mkstemp or similar atomic operations would prevent this class of attack from succeeding.