Security researcher Gregory Fleischer demonstrated a
problem with the HTTP Referer: (sic) header sent with requests
to URLs containing Basic Authentication credentials with empty usernames.
In these cases a number of leading characters, based on the length of the
password in the URL, are removed from the referrer hostname. Fleischer
pointed out that websites which only check the Referer: header
to protect against Cross-Site Request Forgery (CSRF) could be attacked using
this flaw. This concept was based on and expanded from a post to the
sla.ckers.org forum by security researcher RSnake.
Vulmon