Snort mailing list archives
Re: 1337 Bot and TCP options detection
From: FOULDE Damien <damien.foulde () axians com>
Date: Fri, 6 Jan 2017 15:02:12 +0000
Hello Joshua, It seems fine. If you want to be sure you should check by providing a packet capture to a snort instance configured with these rules. If don’t have any sample, you may create one using a packet crafting tool (http://resources.infosecinstitute.com/15-best-free-packet-crafting-tools/) Regards, Damien De : joshua burgess [mailto:avonyxx () hotmail com] Envoyé : mardi 3 janvier 2017 17:58 À : FOULDE Damien Cc : snort-sigs () lists sourceforge net Objet : Re: 1337 Bot and TCP options detection Sorry to resurrect this older thread... Would this work? alert ip $EXTERNAL_NET any -> $HOME_NET any (msg:"1337 DDoS Tool"; content:"|01 03 03 07|"; flowbits:set,1337; reference:url,https://www.incapsula.com/blog/650gbps-ddos-attack-leet-botnet .html; classtype:attempted-dos; sid:X; rev:1;) alert tcp $EXTERNAL_NET any -> $HOME_NET any (msg:"1337 DDoS Tool"; flowbits:isset,1337; flags:S; dsize:799<>936; reference:url,https://www.incapsula.com/blog/650gbps-ddos-attack-leet-botnet .html; classtype:attempted-dos; sid:X; rev:1;) Sent from Outlook <http://aka.ms/weboutlook> _____ From: FOULDE Damien <damien.foulde () axians com> Sent: Wednesday, December 28, 2016 9:23:21 AM To: joshua burgess Cc: snort-sigs () lists sourceforge net Subject: RE: 1337 Bot and TCP options detection Hello Joshua, You may write an ip rule, not a tcp one, to be able to match on the |01 03 03 07| content in the TCP header. However writing the snort rule through this way will prevent you to use the “flags” keyword reserved for the tcp rules. Regards, Damien De : joshua burgess [mailto:avonyxx () hotmail com] Envoyé : mercredi 28 décembre 2016 13:51 À : snort-sigs () lists sourceforge net Objet : [Snort-sigs] 1337 Bot and TCP options detection To check a few boxes, I'm trying to gen up two signatures designed to detect the latest 1337 bot that Imperva wrote about (https://www.incapsula.com/blog/650gbps-ddos-attack-leet-botnet.html) Basically I'm trying to write a signature designed to detect the TCP options which spell out 1337 as well as an abnormally large SYN packet ranging from 799 to 936. I don't know SNORT supports my specifying the TCP options like: Number: No-Operation (NOP) (1) Kind: Window Scale (3) Length: (3) Shift count: (7) Could I do it with"content" only, it doesn't seem likely but I'm running out of ideas... alert tcp $EXTERNAL_NET any -> $HOME_NET any (msg:"1337 DDoS Tool"; flags:S; content:"Number: No-Operation (NOP) (1)"; content:"Kind: Window Scale (3)"; content:"Length: (3)"; content:"Shift count: (7)"; reference:url,https://www.incapsula.com/blog/650gbps-ddos-attack-leet-botnet .html; classtype:attempted-dos; sid:6000049; rev:1;) As far as writing a signature to look for just the SYN packet size would this work to set two different sizes? alert tcp $EXTERNAL_NET any -> $HOME_NET any (msg:"1337 DDoS Tool"; flags:S; dsize:>799; dsize:<936; reference:url,https://www.incapsula.com/blog/650gbps-ddos-attack-leet-botnet .html; classtype:attempted-dos; sid:6000049; rev:1;) Any help would be awesome. Thanks! Sent from Outlook <http://aka.ms/weboutlook>
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Current thread:
- Re: 1337 Bot and TCP options detection joshua burgess (Jan 03)
- Re: 1337 Bot and TCP options detection FOULDE Damien (Jan 06)