In the HAX site editor, users can create a website block to load another site in an iframe. The application allows users to supply a target URL in the website block. When the HAX site is visited, the client's browser will query the supplied URL.
Set the URL in an iframe pointing to an attacker-controlled server running Responder
Once another user visits the site, they are prompted to sign in.
If a user inputs credentials, the username and password hash are outputted in Responder.
Impact
An authenticated attacker can create a HAX site with a website block pointing at an attacker-controlled server running Responder or a similar tool. The attacker can then conduct a phishing attack by convincing another user to visit their malicious HAX site to harvest credentials.