[Snort-sigs] Help with a signature

Jamie jamie.riden at ...2420...
Sun Sep 16 01:51:10 EDT 2012


Argh, sorry. I will go and read the current manual as penance :) 

Sent from a mobile device


On 15 Sep 2012, at 21:56, Alex Kirk <akirk at ...435...> wrote:

> Actually, you just want to use http_uri as a modifier to the content match. uricontent is long since deprecated.
> 
> Also, given that I see your PCAP is missing bytes, you might want to try on a more complete PCAP. You may be running into confusion with the stream or http preprocessors, which could be discarding the incomplete request.
> 
> On Sep 15, 2012 10:25 AM, "Jamie Riden" <jamie.riden at ...2420...> wrote:
> 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 at ...3732...> 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.co m%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 at ...3509... / jamie.riden at ...2420...
> 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.
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> http://info.appdynamics.com/FreeJavaPerformanceDownload.html
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