The ASP.NET DoS flaw that has recently been revealed at the Chaos Communication Congress in Berlin has been patched by Microsoft in almost record time, but users who have not already implemented the patch should definitely hop to it as the proof-of-concept exploit code for the vulnerability has been made public.
“The bulletin fixes the DOS attack vector by providing a limit to the number of variables that can be submitted for a single HTTP POST request,” Qualys’ CTO Wolfgang Kandek commented on Microsoft’s response. “The default limit is 500 which should be enough for normal web applications, but still low enough to neutralize the attack as described by the security researchers in Germany.”
The existence of the PoC code was confirmed a couple of days ago via a post on the Full Disclosure mailing list and the code itself made available for download on GitHub.
The vulnerability also affects several vendors’ web application platforms – PHP, Oracle, Phython, Ruby and others – for which the patches are still not rolled out.