Snort mailing list archives
Re: Serious problems Snort 2.9 with relative content matches using http_inspect preprocessor and http_uri keyword
From: L0rd Ch0de1m0rt <l0rdch0de1m0rt () gmail com>
Date: Thu, 7 Nov 2013 16:42:22 -0500
Hello. @Bad Horse: I tried http_raw_uri and it still does not work. That is good point about the colon in the uri. The funny thing is that if I increase the distance, it WILL work so it seems that maybe the parser it getting "stuck" on the first content match (0x2F) and not evaluating everything in full. To test, I tried this rule and it DID work! : alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:"Dont Cry 4 Me Trojanina"; flow:established, to_server; content:"GET"; http_method; content:"|2F|"; http_uri; content:"|3A|"; http_uri; distance:1; within:50;) @Baggy: I tried a number of versions and the latest was 2.9.5.3 I believe, is that still supported? Thanks for everyones' help. Cheers, Lord C. On Thu, Nov 7, 2013 at 12:31 PM, Bhagya Bantwal <bbantwal () sourcefire com>wrote:
Hello, Have you tested with snort version snort 2.9.5.5? With this snort version I see the alert as expected. If it still doesn't work, you can send me your pcap & conf and I will take a look. Thanks! B On Wed, Nov 6, 2013 at 2:01 PM, L0rd Ch0de1m0rt <l0rdch0de1m0rt () gmail com>wrote:Hello, Previously I posted on this list with an email subject of, "distance, within, and negated matches". Today I bring another issue that I am having that I believes could be related and is non-trivial and super serious. When I analyze it I believe that relative (1 byte?) content matches are not being properly applied in the http_uri buffer. Other buffers for the http preprocessor may be affected as well but I have not tested them but I won't be suprised if they are also infected by this bug. This is an example of the rule Im using: alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:"Dont Cry 4 Me Trojanina"; flow:established, to_server; content:"GET"; http_method; content:"|2F|"; http_uri; content:"|3A|"; http_uri; distance:1; within:20;) Using a simple pcap ("Follow TCP stream" output from Ethereal is here:) GET /iused/2/trust/the.http_preprocessor/sad1/cr1090hs:SN-IF-FF- HTTP/1.1 The rule does not alert even though the Snort output shows that the HTTP data is being properly recognized and processed by the http_inspect preprocessor. The Snort output shows that the specific GET request is being recognized as a HTTP "GET" request. When I remove the http_inspect directives, the rule starts to work, this is an example: alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:"Dont Cry 4 Me Trojanina"; flow:established, to_server; content:"GET"; http_method; content:"|2F|"; content:"|3A|"; distance:1; within:20;) Is this (still?) a known issue? I have tested this on multiple different versions of Snort 2.9. Cheers, Lord C. ------------------------------------------------------------------------------ November Webinars for C, C++, Fortran Developers Accelerate application performance with scalable programming models. Explore techniques for threading, error checking, porting, and tuning. Get the most from the latest Intel processors and coprocessors. See abstracts and register http://pubads.g.doubleclick.net/gampad/clk?id=60136231&iu=/4140/ostg.clktrk _______________________________________________ Snort-devel mailing list Snort-devel () lists sourceforge net https://lists.sourceforge.net/lists/listinfo/snort-devel Archive: http://sourceforge.net/mailarchive/forum.php?forum_name=snort-devel Please visit http://blog.snort.org for the latest news about Snort!
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Current thread:
- Serious problems Snort 2.9 with relative content matches using http_inspect preprocessor and http_uri keyword L0rd Ch0de1m0rt (Nov 06)
- Re: [Snort-devel] Serious problems Snort 2.9 with relative content matches using http_inspect preprocessor and http_uri keyword Bad Horse (Nov 07)
- Re: Serious problems Snort 2.9 with relative content matches using http_inspect preprocessor and http_uri keyword Bhagya Bantwal (Nov 07)
- Re: Serious problems Snort 2.9 with relative content matches using http_inspect preprocessor and http_uri keyword L0rd Ch0de1m0rt (Nov 07)
- Re: [Snort-sigs] Serious problems Snort 2.9 with relative content matches using http_inspect preprocessor and http_uri keyword rmkml (Nov 08)
- Re: Serious problems Snort 2.9 with relative content matches using http_inspect preprocessor and http_uri keyword L0rd Ch0de1m0rt (Nov 20)
- Re: Serious problems Snort 2.9 with relative content matches using http_inspect preprocessor and http_uri keyword rmkml (Nov 20)
- Re: [Snort-devel] Serious problems Snort 2.9 with relative content matches using http_inspect preprocessor and http_uri keyword Bhagya Bantwal (Nov 22)
- Re: Serious problems Snort 2.9 with relative content matches using http_inspect preprocessor and http_uri keyword L0rd Ch0de1m0rt (Dec 04)
- Re: [Snort-users] Serious problems Snort 2.9 with relative content matches using http_inspect preprocessor and http_uri keyword rmkml (Dec 04)
- Re: [Snort-users] Serious problems Snort 2.9 with relative content matches using http_inspect preprocessor and http_uri keyword L0rd Ch0de1m0rt (Dec 05)
- Re: [Snort-users] Serious problems Snort 2.9 with relative content matches using http_inspect preprocessor and http_uri keyword Joel Esler (jesler) (Dec 09)
- Re: [Snort-users] [Snort-devel] Serious problems Snort 2.9 with relative content matches using http_inspect preprocessor and http_uri keyword lists () packetmail net (Dec 09)
- Re: [Snort-sigs] [Snort-users] Serious problems Snort 2.9 with relative content matches using http_inspect preprocessor and http_uri keyword Joel Esler (jesler) (Dec 09)
- Re: Serious problems Snort 2.9 with relative content matches using http_inspect preprocessor and http_uri keyword L0rd Ch0de1m0rt (Nov 07)