CVE-2003-1366 in OpenBSD
Summary
by MITRE
chpass in OpenBSD 2.0 through 3.2 allows local users to read portions of arbitrary files via a hard link attack on a temporary file used to store user database information.
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Analysis
by VulDB Data Team • 12/23/2024
The vulnerability described in CVE-2003-1366 represents a critical security flaw in the chpass utility of OpenBSD versions 2.0 through 3.2. This issue stems from improper handling of temporary files during user database modifications, creating a race condition that can be exploited by local attackers to gain unauthorized access to sensitive system information. The chpass command, which is used to change user passwords and other account information, relies on temporary files to store intermediate database states during the modification process.
The technical implementation of this vulnerability involves a hard link attack against a temporary file created by the chpass utility. When a user modifies their password or account information, chpass creates a temporary file to hold the updated user database entries before committing changes to the permanent database. The flaw occurs because the temporary file is created with predictable naming and insufficient permissions, allowing a malicious local user to establish a hard link to this temporary file before the legitimate process can write to it. This race condition enables the attacker to read or manipulate data that should remain confidential.
From an operational impact perspective, this vulnerability compromises the confidentiality and integrity of user account information stored in the system's password database. Attackers can potentially read sensitive portions of the user database, including hashed passwords, user IDs, and other account-related information that may be used for privilege escalation or further attacks. The vulnerability affects all local users on the system, making it particularly dangerous in multi-user environments where users may not be trusted. This issue directly violates the principle of least privilege and can lead to unauthorized access to system resources that should remain protected.
The vulnerability aligns with CWE-362, which describes race conditions that can occur when multiple processes access shared resources without proper synchronization. Additionally, this flaw relates to ATT&CK technique T1068, which covers "Exploitation for Privilege Escalation" through local privilege escalation methods. The attack vector demonstrates how seemingly benign system utilities can be exploited when proper file handling security measures are not implemented. The issue also connects to CWE-276, which addresses improper file permissions, as the temporary file creation process fails to establish appropriate access controls.
Mitigation strategies for this vulnerability include updating to OpenBSD versions beyond 3.2, where the issue has been resolved through proper temporary file handling mechanisms. System administrators should ensure that all systems are running patched versions of the operating system and that proper file permissions are enforced during temporary file creation. The fix typically involves using secure temporary file creation methods that prevent symbolic or hard link attacks, such as creating files with exclusive access permissions or using atomic file replacement techniques. Organizations should also implement regular security audits to identify and remediate similar race condition vulnerabilities in other system utilities. Additional protective measures include monitoring for unauthorized file system changes and implementing proper access controls that limit local user privileges to prevent exploitation of such vulnerabilities.