Web Hack List

Other nomination

Enumerating logins via Abuse of Functionality vulnerabilities

Reports that the username-availability checkers on large sites are an abuse-of-functionality flaw that leaks valid logins. On YouTube's signup form the Check Availability AJAX response distinguishes existing from free names, and with no anti-automation the check can be brute-forced over a wordlist to build a list of real accounts for password attacks.

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