Snort mailing list archives
Re: Question about a Snort rule
From: Miso Patel <miso.patel () gmail com>
Date: Fri, 25 Feb 2011 09:55:02 -0600
OK, I now understand why just looking for 'flags:S;' doesn't make sense but we want to alert on a situation where there is an established UDP connection AND 'iPad' in the URI so we are trying this one now (without luck but I feel we are getting closer): alert udp $HOME_NET any -> $EXTERNAL_NET any (msg:"iPad related HTTP request"; content:"iPad"; http_uri; nocase; flags:A+; classtype:bad-unknown; reference:url,www.apple.com/ipad/; sid:18954545; rev:2;) Thanks. Miso, CISO On 2/25/11, Nigel Houghton <nhoughton () sourcefire com> wrote:
On Fri, 25 Feb 2011 09:21:14 -0600, Miso Patel wrote:My engineers are having trouble with a custom rule: alert udp $HOME_NET any -> $EXTERNAL_NET any (msg:"iPad related HTTP request"; content:"iPad"; http_uri; nocase; flags:S; classtype:bad-unknown; reference:url,www.apple.com/ipad/; sid:18954545; rev:1;) Any help would be appreciated. The rule does not seem to be alerting for some reason and I think this could be a bug with Snort. Thanks. Miso, CISOYour rule is looking for "iPad" in a URI. So for the event to occur you would need something like http://www.foobar.com/foo/iPad Additionally, you are using "flags:S;" so the only data you are looking at is in SYN packets, so there won't be a URI in the packets anyway. Take a look at the latest Snort manual, there are examples of rules using the http options in there, get some packet capture data of the traffic you wish to detect and take it from there. I'm guessing you will have more questions as you proceed, feel free to email the list with them. Send your revised rule to the list if you like for further inspection. -- Nigel Houghton Head Mentalist SF VRT Department of Intelligence Excellence http://vrt-blog.snort.org/ && http://labs.snort.org/
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Current thread:
- Question about a Snort rule Miso Patel (Feb 25)
- Re: Question about a Snort rule Will Metcalf (Feb 25)
- Re: Question about a Snort rule Korodev (Feb 25)
- Re: Question about a Snort rule Nigel Houghton (Feb 25)
- Re: Question about a Snort rule Miso Patel (Feb 25)
- Re: Question about a Snort rule Nigel Houghton (Feb 25)
- Re: Question about a Snort rule Matt Olney (Feb 25)
- Re: Question about a Snort rule Miso Patel (Feb 25)
- Re: Question about a Snort rule Randal T. Rioux (Feb 25)