Certain configurations of rlogind could allow a remote attacker to gain unauthorized access to a targeted system.
If a trusted host or trusted users have been established, rlogin and rsh services allow a user to log in or execute commands without authentication. A trusted host is set up by placing the name of a specific host or a plus symbol in the file /etc/hosts.equiv. Trusted users will have the .rhosts file in their home directory, which contains the names of trusted hosts the user may log in to. Two pluses (+ +) in this file will allow any user from any machine to log in.
In most environments, rsh and rlogin are often considered deprecated and insecure as they offer no transport security and transmit username and password information in clear text. On production systems, the services are likely disabled, removing any potential for exploitation. Administrators should use secure remote terminals such as SSH in place of rsh and rlogin.
Certain configurations of rlogind could allow a remote attacker to gain unauthorized access to a targeted system via the root, guest or nobody user accounts. A successful attack could allow the attacker to use the unauthorized system access for malicious activity or to launch additional attacks.
Administrators are advised to implement an intrusion prevention system (IPS) or intrusion detection system (IDS) to help detect and prevent attacks that attempt to exploit this vulnerability. IPS and IDS devices may detect and block attempts to access the rsh and rlogin services and their related hosts.equiv and .rhosts files as potential exploit activity.
The security vulnerability applies to the following combinations of products.
Security Activity Bulletin
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