CVE-2001-1555 in Solaris
Summary
by MITRE
pt_chmod in Solaris 8 does not call fdetach to reset terminal privileges when users log out of terminals, which allows local users to write to other users terminals by modifying the ACL of a TTY.
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Analysis
by VulDB Data Team • 08/27/2019
The vulnerability described in CVE-2001-1555 represents a critical privilege escalation issue within the Solaris 8 operating system's terminal management mechanisms. This flaw specifically affects the pt_chmod function which is responsible for managing permissions on pseudo-terminal devices. The core problem lies in the improper handling of terminal privileges during user logout procedures, creating a persistent security gap that can be exploited by local attackers to gain unauthorized access to other users' terminal sessions.
The technical root cause of this vulnerability stems from the failure of the pt_chmod function to execute the fdetach operation when users terminate their terminal sessions. This omission leaves terminal device permissions in an inconsistent state, allowing malicious local users to manipulate the access control lists of terminal devices. The vulnerability operates at the kernel level where pseudo-terminal management occurs, making it particularly dangerous as it bypasses normal user permission checks and privilege boundaries that should normally protect terminal sessions from unauthorized access.
From an operational perspective, this vulnerability enables local users to perform what is known as terminal hijacking or session manipulation attacks. An attacker can exploit this flaw to write to another user's terminal device by modifying the Access Control List (ACL) of a TTY device, effectively allowing them to intercept or manipulate input/output operations that should be restricted to specific users. This capability can lead to information disclosure, session hijacking, and potential privilege escalation within the system's security model. The vulnerability is particularly concerning because it affects the fundamental security assumptions of terminal-based access controls that are critical to multi-user systems.
The impact of this vulnerability aligns with CWE-264, which addresses permissions, privileges, and access controls, and can be mapped to ATT&CK technique T1068 which covers local privilege escalation through improper permissions. The flaw demonstrates how inadequate cleanup of system resources during user session termination can create persistent security weaknesses that remain exploitable until patched. Organizations running Solaris 8 systems were particularly vulnerable to this type of attack as it allowed attackers to establish unauthorized access to other users' terminal sessions without requiring elevated privileges or complex exploitation techniques.
Mitigation strategies for CVE-2001-1555 require immediate patching of the Solaris 8 operating system with the appropriate security updates provided by Sun Microsystems. System administrators should also implement monitoring for unauthorized terminal access attempts and consider implementing additional access controls for terminal devices. The vulnerability highlights the importance of proper resource cleanup and privilege management during system operations, particularly during user session termination processes. Organizations should conduct thorough security assessments of their terminal management systems and ensure that all system components properly handle resource cleanup to prevent similar vulnerabilities from persisting in their environments.