Interesting. I played around with the rules some, and figured out why snort wasn't finding it with the .ida rule. Since I'm only logging the first 100 bytes of data, the .ida rule misses it because part of the criteria of the rule is for data size to be greater than 239 bytes. I've since adjusted my rule to not care about the dsize for the .ida rule. Now its catching it fine. -Joe --- Martin Roesch <roeschat_private> wrote: > That's a rule ordering issue, I'm pretty sure we > fixed that one in > 1.8-RELEASE... > > -Marty > > Joe Smith wrote: > > > > Hey all, > > > > Just got this .ida attack on my sensors. This is > > cute, how it splits the GET from the default.ida? > > query. > > > > Please note that while snort did detect it, it > wasn't > > detected by the .ida rule. Instead, it detected > > it as a whisker splice attack. > > > > alert TCP $EXTERNAL any -> $INTERNAL 80 (msg: > > > "IDS415/web-misc_http-whisker-splicing-attack-tab"; > > dsize: <5; flags: A+; content: "|09|"; classtype: > > suspicious; reference: arachnids,415;) > > > > alert TCP $EXTERNAL any -> $INTERNAL 80 (msg: > > "IDS552/web-iis_IIS ISAPI Overflow ida"; dsize: > >239; > > flags: A+; uricontent: ".ida?"; classtype: > > system-or-info-attempt; reference: arachnids,552;) > > > > I'm guessing that once snort found a match with > > whisker, it stopped looking for other matches. > > > > I've included the relavent frames for your review. > > > > 63.241.137.194-attacker my.poor.website > > HTTP GET > > Frame 4 (60 on wire, 60 captured) > > Ethernet II > > Internet Protocol > > Transmission Control Protocol, Src Port: 21500 > > (21500), Dst Port: 80 (80), Seq: 3988343872, Ack: > > 2181442487 > > Hypertext Transfer Protocol > > > > 0 00d0 b790 dd6f 0002 1724 4800 0800 4500 > > .....o...$H...E. > > 10 002c 105a 4000 7206 9c64 3ff1 89c2 3f59 > > .,.Z@.r..d?...?Y > > 20 5301 53fc 0050 edb9 4c40 8206 2bb7 5018 > > S.S..P..L@..+.P. > > 30 40b0 3ba1 0000 4745 5420 0000 > > @.;...GET .. > > > > 63.241.137.194-attacker my.poor.website > > HTTP Continuation > > Frame 5 (1434 on wire, 100 captured) > > Ethernet II > > Internet Protocol > > Transmission Control Protocol, Src Port: 21500 > > (21500), Dst Port: 80 (80), Seq: 3988343876, Ack: > > 2181442487 > > Hypertext Transfer Protocol > > > > 0 00d0 b790 dd6f 0002 1724 4800 0800 4500 > > .....o...$H...E. > > 10 058c 105b 4000 7206 9703 3ff1 89c2 3f59 > > ...[@.r...?...?Y > > 20 5301 53fc 0050 edb9 4c44 8206 2bb7 5018 > > S.S..P..LD..+.P. > > 30 40b0 0109 0000 2f64 6566 6175 6c74 2e69 > > @...../default.i > > 40 6461 3f4e 4e4e 4e4e 4e4e 4e4e 4e4e 4e4e > > da?NNNNNNNNNNNNN > > 50 4e4e 4e4e 4e4e 4e4e 4e4e 4e4e 4e4e 4e4e > > NNNNNNNNNNNNNNNN > > 60 4e4e 4e4e > NNNN > > > > > > __________________________________________________ > > Do You Yahoo!? > > Get personalized email addresses from Yahoo! Mail > > http://personal.mail.yahoo.com/ > > -- > Martin Roesch > roeschat_private > http://www.sourcefire.com - http://www.snort.org __________________________________________________ Do You Yahoo!? Get personalized email addresses from Yahoo! Mail http://personal.mail.yahoo.com/ ---------------------------------------------------------------------------- This list is provided by the SecurityFocus ARIS analyzer service. For more information on this free incident handling, management and tracking system please see: http://aris.securityfocus.com
This archive was generated by hypermail 2b30 : Thu Jul 19 2001 - 16:39:49 PDT