Barracuda Networks Cloud Series – Filter Bypass Vulnerability
A filter bypass vulnerability has been discovered in the official Barracuda Networks Cloud Series Appliance Applications 2014-Q1. The filter bypass issue allows an attacker to bypass the secure filter validation of the service to execute malicious script codes. The barracuda filter blocks for example standard iframes, scripts and other invalid code context: The cloud service has a own exception-handling to parse or encode malicious injected web context. The mechanism filters the first request and sanitizes the output in every input field. During a pentest we injected a standard iframe to check and provoke the validation. The frame got blocked! In the next step the attacker splits (%20%20%20) the request and injects at the end an onload frame to an external malicious source. The second iframe with the onload alert executes the script codes after the validation encoded only the first script code tag. The santization of the input field does not filter the onload frame.
