CVE-2005-2714 in Mac OS X
Summary
by MITRE
passwd in Directory Services in Mac OS X 10.3.x before 10.3.9 and 10.4.x before 10.4.5 allows local users to overwrite arbitrary files via a symlink attack on the .pwtmp.[PID] temporary file.
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Analysis
by VulDB Data Team • 07/07/2021
This vulnerability exists in the passwd command implementation within Mac OS X Directory Services, specifically affecting versions 10.3.x before 10.3.9 and 10.4.x before 10.4.5. The flaw represents a classic symlink attack vector that exploits improper handling of temporary files during password updates. When the passwd command executes, it creates a temporary file named .pwtmp.[PID] where PID represents the process identifier. This temporary file serves as a staging area for password changes before they are committed to the system password database.
The technical implementation of this vulnerability stems from the insecure creation of temporary files without proper validation of the file system state. An attacker with local access can create a symbolic link with the name .pwtmp.[PID] in the directory where the passwd command expects to create its temporary file. When the passwd command runs and attempts to write to this location, it inadvertently writes data to the target file specified by the attacker's symbolic link rather than to the intended temporary file. This behavior violates the principle of least privilege and demonstrates a lack of proper file system access controls during temporary file creation.
The operational impact of this vulnerability is significant as it allows local attackers to overwrite arbitrary files on the system with the permissions of the user running the passwd command. In practice, this means that an attacker could potentially overwrite critical system files, configuration files, or even files owned by other users if the passwd command is executed with elevated privileges. The vulnerability is particularly dangerous because it requires minimal privileges to exploit and can be leveraged to gain persistence or escalate privileges within the system. This aligns with ATT&CK technique T1068 which covers privilege escalation through exploitation of system vulnerabilities.
The vulnerability also relates to CWE-377, which addresses insecure temporary file creation, and CWE-378, which covers creation of temporary files with insecure permissions. These weaknesses in the implementation of temporary file handling create opportunities for attackers to manipulate the file system in unexpected ways. The issue is further compounded by the fact that this vulnerability affects the core system administration functionality, making it a high-value target for exploitation. The attack vector is particularly effective because it leverages legitimate system functionality to achieve malicious goals, making detection more difficult.
Mitigation strategies for this vulnerability include updating to the patched versions of Mac OS X 10.3.9 and 10.4.5, which properly implement secure temporary file creation mechanisms. System administrators should also implement proper file system permissions and monitor for unauthorized symbolic link creation in system directories. The fix typically involves using secure temporary file creation functions that ensure the temporary file is created with proper permissions and that the file system state is validated before file operations occur. Additionally, implementing mandatory access controls and monitoring for suspicious file system activities can help detect exploitation attempts. This vulnerability highlights the importance of secure coding practices and proper temporary file handling in system administration tools, emphasizing that even basic utilities can become attack vectors when proper security measures are not implemented.