CVE-2007-1589 in TrueCrypt
Summary
by MITRE
TrueCrypt before 4.3, when set-euid mode is used on Linux, allows local users to cause a denial of service (filesystem unavailability) by dismounting a volume mounted by a different user.
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Analysis
by VulDB Data Team • 08/27/2018
The vulnerability described in CVE-2007-1589 represents a significant privilege escalation and denial of service weakness within the TrueCrypt disk encryption software version 4.3 and earlier. This flaw specifically affects Linux systems where TrueCrypt operates in set-euid mode, a security mechanism that allows the program to temporarily assume the privileges of the user who owns the file system being accessed. The vulnerability stems from improper access control mechanisms that fail to validate user permissions when handling volume dismount operations, creating a scenario where unauthorized users can disrupt system operations through seemingly benign actions.
The technical exploitation of this vulnerability occurs when a local user attempts to dismount a TrueCrypt volume that was mounted by another user account. In set-euid mode, TrueCrypt elevates its privileges to match those of the owner of the mounted volume, but the software fails to properly verify that the dismounting user has legitimate authorization to perform this operation. This design flaw creates a race condition and access control bypass that allows any local user to interfere with volumes belonging to other users, effectively causing a denial of service condition where the filesystem becomes unavailable to its legitimate owner.
From an operational impact perspective, this vulnerability compromises the fundamental security model of TrueCrypt by undermining the principle of least privilege and user isolation. The flaw enables local privilege escalation attacks that can result in complete system availability disruption, as users can render encrypted volumes inaccessible to their legitimate owners. This creates a particularly dangerous scenario in multi-user environments where users might not be trusted with full system access, yet can still cause significant operational disruptions through simple dismount commands. The vulnerability also violates security standards such as those outlined in the Common Weakness Enumeration CWE-284, which addresses improper access control, and aligns with ATT&CK technique T1068, which covers local privilege escalation through improper privilege management.
Mitigation strategies for CVE-2007-1589 should prioritize immediate software updates to TrueCrypt version 4.3 or later, which addressed the core access control issues in the set-euid implementation. System administrators should also implement additional monitoring and logging of volume mount and dismount operations to detect unauthorized access attempts. The use of more secure encryption solutions such as dm-crypt with LUKS or other modern encryption frameworks that properly handle user isolation and privilege escalation should be considered as long-term replacements for vulnerable TrueCrypt installations. Additionally, implementing proper user access controls, restricting local system access to trusted users only, and ensuring that set-euid functionality is disabled or properly audited when not required can significantly reduce the risk exposure from this vulnerability. Organizations should also conduct regular security assessments to identify and remediate similar access control weaknesses in other system components and encryption software implementations.