CVE-2001-0887 in xSANE
Summary
by MITRE
xSANE 0.81 and earlier allows local users to modify files of other xSANE users via a symlink attack on temporary files.
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Analysis
by VulDB Data Team • 05/02/2019
The vulnerability identified as CVE-2001-0887 represents a classic privilege escalation and data integrity issue affecting xSANE version 0.81 and earlier. This security flaw resides in the application's handling of temporary files during file operations, creating a window of opportunity for local attackers to manipulate files owned by other users through symbolic link manipulation techniques. The vulnerability specifically targets the insecure temporary file creation practices that were prevalent in many applications of that era, demonstrating the critical importance of proper file system permissions and atomic operations in security-sensitive software.
The technical implementation of this vulnerability stems from xSANE's failure to properly validate or secure temporary file creation processes. When the application generates temporary files during operations such as image processing or file transfers, it creates these files with predictable names and locations without implementing proper security measures to prevent symbolic link attacks. An attacker with access to the system can create malicious symbolic links in the same directories where xSANE creates temporary files, effectively allowing them to redirect file operations to arbitrary locations. This type of attack falls under the category of time-of-check to time-of-use vulnerabilities, where the application checks for file existence and permissions at one point in time, but the actual file operations occur later when the attacker may have already manipulated the symbolic link structure.
The operational impact of this vulnerability extends beyond simple file modification, as it enables unauthorized access to potentially sensitive user data and can facilitate more sophisticated attacks. Local users who gain knowledge of the vulnerability can exploit it to read, modify, or delete files belonging to other users running xSANE processes. This creates a significant risk for multi-user systems where different users may be processing confidential documents or images. The attack vector is particularly concerning because it requires minimal privileges beyond local system access and can be executed automatically through shell scripts or automated tools. From a cybersecurity perspective, this vulnerability demonstrates how seemingly minor implementation flaws in file handling can result in substantial security breaches, aligning with common attack patterns documented in the attack tree methodology.
The vulnerability is classified under CWE-377: Insecure Temporary Files and CWE-378: Creation of Temporary Files with Insecure Permissions, both of which are well-documented weaknesses in software security practices. The attack pattern corresponds to techniques described in the MITRE ATT&CK framework under T1059.007: Command and Scripting Interpreter: PowerShell and T1566: Phishing, though the direct execution here is more focused on local privilege escalation rather than network-based attacks. The root cause of this vulnerability highlights the need for proper file system security practices including the use of secure temporary file creation functions, proper file permissions, and atomic operations. The issue also relates to broader concepts of least privilege and secure coding practices that are fundamental to preventing such attacks. Organizations using affected versions of xSANE should implement immediate mitigations including updating to patched versions, implementing proper file system permissions, and conducting security reviews of temporary file handling in other applications. The vulnerability serves as a historical example of how inadequate attention to file system security can create persistent risks, emphasizing the importance of regular security audits and adherence to secure coding standards.