COMMAND
fpcount.exe
SYSTEMS AFFECTED
Win NT with Front Page and IIS
PROBLEM
Dave Litchfield posted following. Those of you that have IIS and
MS FrontPage on your server will most likely have heard of
fpcount.exe. Fpcount.exe has obviously been designed so that if
some-one tries following the following URL:
http://comp.com/cgi-bin/fpcount.exe?Page=Default.htm|Image=3|Digits=100000
and tries overloading the program, it will just bomb out with
memory exception errors. This was good thinking but they forgot
one thing - negative numbers (note: 8 nines):
http://comp.com/scripts/fpcount.exe?Page=Default.htm|Image=3|Digits=-99999999
The above URL will cause the processor to run at 100% for half an
hour while it calculates (tested on P166 with MMX and 64 Mb of
RAM, Service Pack 3).
When you send a positive number and get the exception errors, DR
Watson will kick in saying just that:
http://comp.com/cgi-bin//fpcount.exe?Page=Default.htm|Image=3|Digits=100000
Dr Watson takes up just under 4000K of memory. If an attacker
reloads the page it seems that after 8 reloads the IIS stops
servicing requests.
SOLUTION
Nothing yet.