CAPEC-40 Manipulating Writeable Terminal Devices

This attack exploits terminal devices that allow themselves to be written to by other users. The attacker sends command strings to the target terminal device hoping that the target user will hit enter and thereby execute the malicious command with their privileges. The attacker can send the results (such as copying /etc/passwd) to a known directory and collect once the attack has succeeded.

1. [Explore] [Identify attacker-writable terminals] Determine if users TTYs are writable by the attacker. 2. [Exploit] [Execute malicious commands] Using one or more vulnerable TTY, execute commands to achieve various impacts.

• User terminals must have a permissive access control such as world writeable that allows normal users to control data on other user's terminals.

• [Low] Ability to discover permissions on terminal devices. Of course, brute force can also be used.

• Confidentiality, Access Control, Authorization: Gain Privileges • Confidentiality: Read Data • Confidentiality, Integrity, Availability: Execute Unauthorized Commands

• Design: Ensure that terminals are only writeable by named owner user and/or administrator • Design: Enforce principle of least privilege