Snort mailing list archives

Re: Help with a signature


From: Jamie Riden <jamie.riden () gmail com>
Date: Sat, 15 Sep 2012 15:22:43 +0100

Not exactly sure why this didn't match, but you should try uricontent
instead of content - it's normalised by the http_preprocessor.

I believe there are some bleeding edge rules which match on =http if you
want to compare - it's a more general RFI signature.

cheers,
 Jamie

On 14 September 2012 14:06, Wilson, Dave <Dave.Wilson () wwt com> wrote:

Hello,****

** **

I'm trying to create a snort rule that will alert on traffic that contains
"rfihub" as part of the url.  Here is an example of the TCP stream of a
packet that I'd want to alert on.****

** **

00000000  47 45 54 20 2f 63 6d 3f  70 69 64 3d 32 30 37 36        GET /cm?
pid=2076****

00000010  32 35 30 66 2d 39 32 63  32 2d 34 65 63 64 2d 39      250f-92c
2-4ecd-9****

00000020  30 34 33 2d 63 63 36 33  65 65 36 63 34 35 37 37      043-cc63
ee6c4577****

00000030  26 64 73 74 3d 68 74 74  70 25 33 41 25 32 46 25      &dst=htt
p%3A%2F%****

00000040  32 46 70 2e 72 66 69 68  75 62 2e 63 6f 6d 25 32       2Fp.rfih
ub.com%2****

00000050  46 63 6d 25 33 46 69 6e
                        Fcm%3Fin ****

00000058  5b 31 32 37 32 20 62 79  74 65 73 20 6d 69 73 73      [1272 by
tes miss****

00000068  69 6e 67 20 69 6e 20 63  61 70 74 75 72 65 20 66      ing in c
apture f****

00000078  69 6c 65 5d
                                        ile]****

0000007C  61 74 68 65 72 2e 63 6f  6d 25 32 46 6d 61 6e 61      ather.com%2Fmana
****

0000008C  67 65 64 66 65 25 32 46  6d 61 6b 65 52 65 71 75     gedfe%2F
makeRequ****

0000009C  65 73 74 2d 6d 61 78 2e  68 74 6d 6c 25 33 46 70     est-max.
html%3Fp****

000000AC  6f 73 25 33 44 57 58 5f  54 6f 70 33 30 30 56 61       os%3DWX_
Top300Va****

000000BC  72 69 61 62 6c 65 26 70  66 3d 0d 0a 43 6f 6f 6b       riable&p
f=..Cook****

000000CC  69 65 3a 20 69 3d 65 31
                   ie: i=e1 ****

00000000  48 54 54 50 2f 31 2e 31  20 33 30 32 20 4f 4b 0d
HTTP/1.1  302 OK.****

00000010  0a 43 6f 6e 74 65 6e 74  2d 54 79 70 65 3a 20 74       .Content
-Type: t****

00000020  65 78 74 2f 68 74 6d 6c  3b 20 63 68 61 72 73 65       ext/html
; charse****

00000030  74 3d 75 74 66 2d 38 0d  0a 50 33 50 3a 20 43 50      t=utf-8.
.P3P: CP****

00000040  3d 22 43 55 52 20 41 44  4d 20 4f 55 52 20 4e 4f        ="CUR AD
M OUR NO****

00000050  52 20 53 54 41 20 4e 49
                  R STA NI ****

** **

** **

Here is the rule I put together:****

** **

** **

alert tcp any any -> any any (msg:"Zeroaccess variant"; content:"|72 66 69
68 75 62|" sid:1000001;)****

** **

** **

When feed the pcap into snort, It'll process it, but not alert.  I've
tried changing the protocol from tcp to http, but snort chokes and tells me
"Bad Protocol: http"****

** **

I'm still very new at writing snort rules, so I apologize in advance for
any helpful details I've left out.  I really appreciate any
assistance...thank you.****

** **

Dave****


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-- 
Jamie Riden / jamie () honeynet org / jamie.riden () gmail com
http://uk.linkedin.com/in/jamieriden
------------------------------------------------------------------------------
How fast is your code?
3 out of 4 devs don\\\'t know how their code performs in production.
Find out how slow your code is with AppDynamics Lite.
http://ad.doubleclick.net/clk;262219672;13503038;z?
http://info.appdynamics.com/FreeJavaPerformanceDownload.html
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