Détail du CAPEC-40

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.

Flux d'exécution

[Identify attacker-writable terminals] Determine if users TTYs are writable by the attacker.

• Determine the permissions for the TTYs found on the system. Any that allow user write to the TTY may be vulnerable.
• Attempt to write to other user TTYs. This approach could leave a trail or alert a user.

[Execute malicious commands] Using one or more vulnerable TTY, execute commands to achieve various impacts.

• Commands that allow reading or writing end user files can be executed.

Conditions préalables

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

Compétences requises

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

Ressources nécessaires

Access to a terminal on the target network

Atténuations

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

Faiblesses connexes

Références

REF-1

Exploiting Software: How to Break Code
G. Hoglund, G. McGraw.

Soumission

Modifications