Snort mailing list archives
Re: help writing snort rule
From: Joel Esler <joel.esler () sourcefire com>
Date: Fri, 26 Jan 2007 14:31:07 -0500
Bill, This is exactly the correct place to ask Snort Rules questions.I suggest you eliminate the "ip" in the rule. Try replacing it with TCP or even using the tcp rule that I jotted down.
Grabbing it out of an email should be easy, however an attachement is not so easy depending upon the type of attachment, for example, if it's a plaintext document or something, yes, it might grab it, but if it's written in Word, or maybe a pdf, since those are formatted differently, it's a bit harder.
So, step one, lets move from ip to tcp, and see how that works. Also, try and eliminate your any any, perhaps change it to any any to HOME_NET any
J On Jan 26, 2007, at 1:58 PM, Bill Lopez wrote:
Thank you for the quick response to my question.I don’t want to keep asking elementary questions in this forum if its not appropriate, please let me know if this isn’t the proper place and direct me to where I can ask basic questions.I wasn’t able to get an alert on the bleeding rulealert tcp any any -> any any (msg: "BLEEDING-EDGE SSN Detected in Clear Text"; flow: established; pcre:"/ ([0-6]\d\d|7[0-256]\d|73 [0-3]|77[0-2])-\d{2}-\d{4} /"; classtype: policy-violation; sid: 2001328; rev:8; )thus the reason for trying to write my own with a small variance in the character string –alert ip any any -> $EXTERNAL_NET any (pcre:"/\d{3}(\s|-)?\d{2} (\s|-)?\d{4}/"; msg:"SSN Detected in Clear Text"; sid: 1000004;)which doesn’t produce an alert either – eventually I want to apply this filter to just traffic from/to mail , telnet, ftp (etc) servers – I can send any variance of xxx-xx-xxxx, xxxxxxxx or xxx xx xxxx via an e-mail, text file attachment or file upload and still never see an alert to the console. I have a simple rule to check for content using a keyword and get alerted when sending that keyword with e-mail, attachment and file upload (this was my test to see if snort was actually alerting correctly) I am only running my test rules with an out of the box snort.conf file.Why wouldn’t either of the above rules alert with (for example) an e-mail sent with 555-55-5555 in the body?Bill Lopez Operating Engineers Trust Funds (626) 356-3524 (626) 255-1066---------------------------------------------------------------------- ---Take Surveys. Earn Cash. Influence the Future of ITJoin SourceForge.net's Techsay panel and you'll get the chance to share youropinions on IT & business topics through brief surveys - and earn cashhttp://www.techsay.com/default.php? page=join.php&p=sourceforge&CID=DEVDEV________________________________ _______________Snort-users mailing list Snort-users () lists sourceforge net Go to this URL to change user options or unsubscribe: https://lists.sourceforge.net/lists/listinfo/snort-users Snort-users list archive: http://www.geocrawler.com/redir-sf.php3?list=snort-users
--Joel joel.esler () sourcefire com http://demo.sourcefire.com/jesler.pgp.key
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_______________________________________________ Snort-users mailing list Snort-users () lists sourceforge net Go to this URL to change user options or unsubscribe: https://lists.sourceforge.net/lists/listinfo/snort-users Snort-users list archive: http://www.geocrawler.com/redir-sf.php3?list=snort-users
Current thread:
- help writing snort rule Bill Lopez (Jan 25)
- Re: help writing snort rule Nerijus Krukauskas (Jan 25)
- Re: help writing snort rule Matt Jonkman (Jan 26)
- Re: help writing snort rule Joel Esler (Jan 26)
- <Possible follow-ups>
- Re: help writing snort rule Bill Lopez (Jan 26)
- Re: help writing snort rule Joel Esler (Jan 26)
- Re: help writing snort rule Blake Hartstein (Jan 26)
- Re: help writing snort rule Bill Lopez (Jan 26)