Sandro Gauci, founder of EnableSecurity, has revealed that six years on from his 2002 report into extended HTML form attacks the problem has simply refused to go away.
The original report included details of how attackers could abuse non-HTTP protocols in order to launch Cross Site Scripting attacks, even in a situation where the target web application was not itself vulnerable to XSS. This applied to most web browsers at the time. Now, he says, not much has changed.
"Six years later I’m releasing an update to this research in this paper. This security vulnerability still affects popular web browsers nowadays."
Gauci lists the following browsers as all being tested and vulnerable:
Internet Explorer 6
Internet Explorer 7
Internet Explorer 8 (beta 1)
Of course, it is not that the vulnerabilities have just been ignored, but rather that these browsers have not managed to make it go away completely. The problem seems to lay with how they block ports, and how attackers exploit browser blacklists by using ports which are not on them.
Gauci concedes that a decent job has been done as far as the web forms which get exchanged with HTML servers are concerned, but not when we start talking about FTP, SMTP or any other non-HTTP server.
"When an attacker can control what is returned by the server, the victim becomes vulnerable to security issues" Gauci says.