Re: ASP.NET __VIEWSTATE crypto validation prone to replay attacks

[Michal Zalewski <lcamtuf@xxxxxxxxx>]

I would also like to point all concerned to an excellent post about
replay attacks on __VIEWSTATE; the post is by Scott Mitchell, the guy
who authored the MSDN article I initially referred to [1]:

http://scottonwriting.net/sowblog/posts/3747.aspx

His article is aimed at developers; Scott explains the issue I
reported in a way that makes it perhaps more clear why putting user
ID, session ID, or other similar data in __VIEWSTATE is not a remedy
by itself, and why reposting __VIEWSTATE is dangerous despite target
script location checks.

[1] http://msdn.microsoft.com/library/en-us/dnaspp/html/viewstate.asp

Cheers,
/mz