Snort mailing list archives
Re: Fwd: Snort catching backup as alert?
From: waldo kitty <wkitty42 () windstream net>
Date: Mon, 19 Aug 2013 13:51:06 -0400
On 8/19/2013 11:32, William Rehnquyst wrote:
The other day my Snort alerted that it had detected shellcode, and the payload information looks just like a snort rule. It seems to be going from my snort server to the backup server. Does that just mean while backup is happening, Snort is detecting shellcode it's looking for in the rule file itself?
probably... but it also means that everything else in the rule has to match the traffic, too...
I would think if that's the case then every single rule in the rule file would be triggered, because everything it's looking for is in there and it's being transmitted. Were these shellcode detections just a fluke then?
simple rules may catch this whereas those using pcre may or may not depending on the rules' possible content matches it is looking for... i'm going to trim the following a bit so as to make it easier to follow and to also give only the SID which is really all that's needed... if the GID is not 1, then it is also needed but in this case, all of your rules are GID:1 (textual rules)...
Below is the payload it captured, which triggered the alert:
1.
sid:17340; rev:3;)
is looking on any port for a simple content only match... yes, this one is likely firing because of seeing that exact string... i note also that the rule is looking for traffic from $EXTERNAL_NET to $HOME_NET and that brings up a few questions: 1. is your backup server external to your network? 2. is this detection happening when your backup server is sending the traffic to a machine in your home net during a restore?
sid:17341; rev:2;)
this rule has three content matches but they are hex coded so not straight strings in the content matches... no idea if this rule is triggering on seeing itself...
sid:17342; rev:2;)
this one is similar to 17341 in that its match is hex coded content...
sid:17343; rev:2;)
the same with this one...
alert ip $EXTERNAL_NET any -> $HOME_NET any (msg:"INDICATOR-SHELLCODE x86 OS agnostic xor
the SID was left out on this one so i don't know what rule it is...
ps. On a side note, pardon my newbie-ness, how does screenshots and attachment work on a mailing list like this? I'm not sure whether they work or not because I never see them in the archive onseclists.org?
it is best to just copy'n'paste the information into a post rather than trying to do screenshots... mainly because graphics are larger than the data you are trying to show... as for them not appearing on seclists, that may be because seclists doesn't allow them and so strips them out... as a general rules, each mailing list is different... some do not allow attachments at all... others allow any attachments up to a certain size... then some restrict the type of attachments and may also apply size restrictions to them... these details should be available in the rules for the list which everyone should read before joining the list... as for other systems that import the list and make it available in another format, they have their own rules... as long as posts made on them that get transferred back to the list conform with the list's rules, there are no problems... -- NOTE: No off-list assistance is given without prior approval. Please keep mailing list traffic on the list unless private contact is specifically requested and granted. ------------------------------------------------------------------------------ Introducing Performance Central, a new site from SourceForge and AppDynamics. Performance Central is your source for news, insights, analysis and resources for efficient Application Performance Management. Visit us today! http://pubads.g.doubleclick.net/gampad/clk?id=48897511&iu=/4140/ostg.clktrk _______________________________________________ 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://sourceforge.net/mailarchive/forum.php?forum_name=snort-users Please visit http://blog.snort.org to stay current on all the latest Snort news!
Current thread:
- Fwd: Snort catching backup as alert? William Rehnquyst (Aug 19)
- Re: Fwd: Snort catching backup as alert? Jefferson, Shawn (Aug 19)
- Re: Fwd: Snort catching backup as alert? waldo kitty (Aug 19)
- Re: Fwd: Snort catching backup as alert? William Rehnquyst (Aug 22)
- Re: Fwd: Snort catching backup as alert? waldo kitty (Aug 22)
- Re: Fwd: Snort catching backup as alert? William Rehnquyst (Aug 22)
- Re: Fwd: Snort catching backup as alert? Alexandre Carmel-Veilleux (Aug 24)
- Re: Fwd: Snort catching backup as alert? waldo kitty (Aug 24)
- Re: Fwd: Snort catching backup as alert? Joel Esler (Aug 25)
- Re: Fwd: Snort catching backup as alert? waldo kitty (Aug 24)