Source: cve@mitre.org
Some implementations of rlogin allow root access if given a -froot parameter.
Critical vulnerability in legacy rlogin implementations allows for unauthorized root access. Exploiting this flaw grants attackers complete control over the compromised system, potentially leading to data breaches and system compromise.
Step 1: Target Identification: Identify systems running vulnerable versions of rlogin.
Step 2: Exploit Trigger: The attacker connects to the target system's rlogin service.
Step 3: Parameter Injection: The attacker sends a crafted rlogin command with the -froot parameter.
Step 4: Authentication Bypass: The vulnerable rlogin implementation fails to properly validate the -froot parameter.
Step 5: Privilege Escalation: The system grants the attacker root privileges.
Step 6: Root Access: The attacker gains full control of the system as root.
The vulnerability stems from a flaw in how rlogin handles the -f flag, specifically when combined with the root user. The program fails to properly validate the user context when the -froot parameter is provided. This leads to a bypass of authentication mechanisms, allowing the attacker to effectively log in as root without providing a password. The root cause is a lack of proper input validation and authorization checks when processing the -f flag, resulting in a privilege escalation vulnerability. The code likely trusts the provided user context without verifying its validity, leading to the unauthorized assignment of root privileges.
Due to the age of this vulnerability, it is unlikely to be directly associated with specific APT groups. However, any threat actor seeking to compromise legacy systems would find this vulnerability highly valuable. Not listed on CISA KEV due to its age and the focus on modern vulnerabilities.
Monitor network traffic for rlogin connections with the -froot parameter.
Analyze system logs for suspicious rlogin login attempts, especially those originating from unexpected sources.
Review system configuration files for the presence of rlogin and its associated configuration, and check for any unusual settings.
Implement host-based intrusion detection systems (HIDS) to monitor for unauthorized root access attempts.
Disable rlogin if it is not required. Use SSH as a secure alternative.
If rlogin is necessary, ensure that it is updated to a patched version that addresses the vulnerability.
Implement strong authentication mechanisms, such as multi-factor authentication (MFA).
Regularly audit system configurations and user accounts to identify and mitigate potential security risks.
Implement network segmentation to limit the impact of a potential compromise.