[Snort-sigs] Excessive alerts on SID 17407 -- Windows help file download

Joel Esler jesler at ...435...
Sun Jan 29 10:39:05 EST 2012

The current rev of that rule is the following:

alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:"FILE-IDENTIFY Microsoft Windows help file download request"; flow:to_server,established; content:".hlp"; fast_pattern; nocase; http_uri; pcre:"/\x2ehlp([\?\x5c\x2f]|$)/smiU"; flowbits:set,file.hlp; reference:cve,2006-3357; reference:cve,2006-4138; classtype:misc-activity; sid:17407; rev:10;)

The most recent change of which was on 2011-12-01.

I suggest using pulledpork for your Rule updates:


Joel Esler
Senior Research Engineer, VRT
OpenSource Community Manager

On Jan 27, 2012, at 1:58 PM, Bachelor, Stephen A CTR USSOCOM HQ wrote:

> This often triggers on content which is not a help file, such as "GET
> /iu/api/res/1.2/Ip7475OzCLIWah.hLpjbYw--/YXBwaWQ9eXZpZ"
> Is there any reason I shouldn't add, after the content rule,
> pcre:"/\.hlp[^a-zA-Z0-9]/smi";
> Original rule text below: 
> 	Rule    alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS
> (msg:"WEB-CLIENT Windows help file download request";
> flow:to_server,established; content:".hlp"; nocase; http_uri;
> metadata:policy balanced-ips drop, policy security-ips drop, service
> http; reference:cve,2006-3357; reference:cve,2006-4138;
> classtype:attempted-user; sid:17407; rev:4; )
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