Source: cve@mitre.org
Vulnerability in login in AT&T System V Release 4 allows local users to gain privileges.
A critical vulnerability in AT&T System V Release 4's login process allows local users to escalate privileges, potentially granting unauthorized access to the entire system. This flaw, dating back to 1991, could enable attackers to bypass security controls and compromise sensitive data. Exploitation is likely to be straightforward, given the age and nature of the vulnerability.
Step 1: Local Access. An attacker gains local access to the vulnerable system, potentially through physical access, compromised user accounts, or other local vulnerabilities. Step 2: Triggering the Vulnerability. The attacker interacts with the login process, potentially by providing crafted input or exploiting a flaw in how the system handles login attempts. Step 3: Exploitation. The attacker leverages the vulnerability to execute arbitrary code or manipulate the system's state. Step 4: Privilege Escalation. The attacker's code execution allows them to elevate their privileges, typically to root or another privileged account. Step 5: System Compromise. With elevated privileges, the attacker gains full control of the system, including access to sensitive data and the ability to install backdoors.
The vulnerability stems from a flaw in the login process of AT&T System V Release 4, likely related to improper handling of user credentials or insufficient privilege checks. The exact root cause is difficult to pinpoint without more specific details, but it likely involves a privilege escalation issue. This could manifest as a format string vulnerability, a buffer overflow in a login-related function, or a race condition where a user's privileges are not correctly validated during the login sequence. The lack of modern security mitigations, such as address space layout randomization (ASLR) and data execution prevention (DEP), would make exploitation significantly easier. The age of the system also suggests a lack of robust input validation and sanitization, further contributing to the vulnerability.
Due to the age of the vulnerability, it's unlikely to be directly targeted by modern APTs. However, it could be a target for older APTs or nation-state actors targeting legacy systems. This vulnerability is not listed on the CISA KEV catalog due to its age and the limited number of systems still running this specific version of AT&T System V Release 4. However, any system running this version is at extreme risk.
Monitor system logs for suspicious login attempts, especially those with unusual input or error messages.
Analyze system logs for unexpected privilege escalation events.
Implement file integrity monitoring to detect unauthorized changes to system binaries and configuration files.
Network traffic analysis may reveal unusual activity associated with compromised accounts.
The primary remediation is to immediately migrate away from AT&T System V Release 4. This operating system is obsolete and no longer receives security updates.
If migration is not immediately possible, isolate the affected system from the network to limit exposure.
Implement strict access controls and monitor user activity.
Review and harden the system's configuration, disabling unnecessary services and features.
Consider using a host-based intrusion detection system (HIDS) to monitor for malicious activity.