[Snort-devel] Content detection in html payload with snort ?
fcharpen at ...2765...
Thu May 19 08:43:38 EDT 2005
I could not found an answer to my problem, so I ask the list :
I use snort to detect attackers playing with my web application.
I try to detect some specific text in html response, like "Bad User" ou
" Warning Mysql Error". But snort stay blind.
1 - Attacker -> web-server : http://server/script.asp?param=' or 1=1--
2 - web-server -> attacker : 200 OK, ......<html>......datatype error....
I try to catch the string "datatype error" with a snort rule like that :
alert tcp $HTTP_SERVERS $HTTP_PORTS -> any any (msg:"web-server attack";
flow:from_server,established; content:"datatype error";
classtype:web-application-attack; sid:80005; rev:1;)
But Snort never detects that.
I try with binary mode, same.
When I sniff with ethereal, the packet I try to catch is like that :
attcker -> web-webser : HTTP : GET http://server/script.asp?param='
web-server -> attacker : HTTP : HTTP/1.1 304 Not Modified
web-server -> attacker : HTTP : Continuation or non-HTTP traffic (*HERE)
If anyone have an idea ?
Frederic Charpentier - Xmco Partners
Security Consulting / Pentest
web : http://www.xmcopartners.com
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