Re: BOTNET-CNC Possible host infection - excessive DNS queries for .eu

[Martin Holste <mcholste () gmail com>]

The sig, as written, will false like crazy on any medium or large
sized network because it does not take into account DNS servers or
SMTP servers (or spam gateways) which do a lot of DNS lookups.

On Mon, Mar 12, 2012 at 9:41 AM, Alex Kirk <akirk () sourcefire com> wrote:
> First, you need the ".eu" bit because you need to have a content match in
> the rule, else performance will suffer massively. Second, and more
> important, the behavior we've seen centers around this particular TLD (and a
> couple of others for which we have rules); we're targeting there to keep
> false positives down.
>
> As far as this picking up other malware - chances are high it will. The rule
> of thumb is to take a look at the domain names in the alerts, and determine
> whether they're legitimate or not (which is usually obvious because
> malicious ones are randomized), and then track back to the boxes generating
> the queries for a thorough scan/investigation.
>
> On Sun, Mar 11, 2012 at 8:00 AM, Yew Chuan Ong <yewchuan88 () gmail com> wrote:
> > Hi,
> >
> > alert udp $HOME_NET any -> $EXTERNAL_NET 53 (msg:"BOTNET-CNC Possible host
> > infection - excessive DNS queries for .eu"; flow:to_server;
> > byte_test:1,!&,0xF8,2; content:"|02|eu|00|"; fast_pattern:only;
> > detection_filter:track by_src, count 100, seconds 10;
> > classtype:trojan-activity; sid:21544; rev:1;)
> >
> > This is the new sig posted on VRT blog recently which aimed to find out
> > malware within the network. I am wondering why we need to specific on the
> > keyword ".eu". Can we tracked the related traffic by using only the
> > threshold?
> >
> > Also, are we aiming on any specific malware besides Murofet and Kazy? I
> > try to google around but can't really get it. Thanks!
> >
> >
> > ------------------------------------------------------------------------------
> > Try before you buy = See our experts in action!
> > The most comprehensive online learning library for Microsoft developers
> > is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3,
> > Metro Style Apps, more. Free future releases when you subscribe now!
> > http://p.sf.net/sfu/learndevnow-dev2
> > _______________________________________________
> > Snort-sigs mailing list
> > Snort-sigs () lists sourceforge net
> > https://lists.sourceforge.net/lists/listinfo/snort-sigs
> > http://www.snort.org
> >
> >
> > Please visit http://blog.snort.org for the latest news about Snort!
>
>
>
>
> --
> Alex Kirk
> AEGIS Program Lead
> Sourcefire Vulnerability Research Team
> +1-410-423-1937
> alex.kirk () sourcefire com
>
> ------------------------------------------------------------------------------
> Try before you buy = See our experts in action!
> The most comprehensive online learning library for Microsoft developers
> is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3,
> Metro Style Apps, more. Free future releases when you subscribe now!
> http://p.sf.net/sfu/learndevnow-dev2
> _______________________________________________
> Snort-sigs mailing list
> Snort-sigs () lists sourceforge net
> https://lists.sourceforge.net/lists/listinfo/snort-sigs
> http://www.snort.org
>
>
> Please visit http://blog.snort.org for the latest news about Snort!

------------------------------------------------------------------------------
Try before you buy = See our experts in action!
The most comprehensive online learning library for Microsoft developers
is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3,
Metro Style Apps, more. Free future releases when you subscribe now!
http://p.sf.net/sfu/learndevnow-dev2
_______________________________________________
Snort-sigs mailing list
Snort-sigs () lists sourceforge net
https://lists.sourceforge.net/lists/listinfo/snort-sigs
http://www.snort.org


Please visit http://blog.snort.org for the latest news about Snort!