OpenC3 COSMOS: Hijacked session token can be used to reset password for persistence

Summary

The OpenC3 password change functionality allows a user to change their password without providing the old password, by accepting a valid session token instead. In assumed breach scenarios, this behaviour can be exploited by an attacker who has already obtained a valid session token, to gain persistence in hijacked account (including admin) and prevent legitimate users from accessing the account.

Details

The design flaw in authentication model (authentication.rb) allows for interchangeable use of password and session tokens for user authentication As old tokens are not revoked upon password reset, an attacker who has obtained a valid session token can continue to authenticate and change the account’s password even after the victim resets it, thereby maintaining persistent control over the compromised account.

PoC

1. Attacker is logged in user account with hijacked valid session token, but not knowing the actual password
2. Legitimate user, as preventive action, changes his password (password123) using old password (password), that he knows, then establishes new session
3. Attacker issues another password change request (in web proxy like Burp) supplying his still valid token as old_password, changing it to attacker-password, from this point preventing any other legitimate users from accessing account

Impact

Persistence of an attacker who obtained valid session token and preventing legitimate users from account access