Re: Help - a possible bot

[Ryan Yagatich <ryany () pantek com>]

Hi,
        You are seeing standard internet traffic originating from your 
LAN/system. In fact, a couple years ago I remember seeing posts similar to 
this which talked about the same concept...  I don't remember what list it 
was on, nor when it occured, but i do remember that it talked about WINS.

Basically, the flow looks like this:

1) network online
2) user types in www.pantek.com in their browser.
3) DNS responds with pantek.com as 64.208.104.215
4) windows system reverse maps address via NetBIOS/WINS/DNS 
        - here is where you are seeing the traffic
5) windows system connects to 64.208.104.215
6) browser displays the happy page

you mentioned that its only on hosts that do not resolve. This is because
there was no reverse mapping for the targetted address via DNS and thus,
the workstation attempted to use alternate methods to resolve the host.

> Is this behavior similar to any known bot infection?
well, a couple more years ago (cant remember when/where/what list) i also 
remember seeing a post about a particular .vbs worm that was working 
around doing things like this, that worm however, was not very popular and 
didn't really get very far. 

Of course, i could be completely wrong, but I could be right. To verify 
any of this as being accurate or incorrect, download ethereal 
(www.ethereal.org) and install it on your system in full capture mode. 
Then do the following:

1) disconnect from the internet
        - so we can get a 'clean slate'
2) start the capture
        - you should only see leftover connection 
          attempts from previous connection, and 
          some netbios broadcasts.
3) connect to the internet
4) do nothing for a little while to see if any traffic occurs
        - you shouldn't really see anything here 
          unless you have things that connect to 
          get system updates (like windowsupdate 
          etc.)
5) browse the web
6) disconnect from the internet
7) wait a few minutes
        - this will make everything cease except 
          for the occasional broadcast.
8) stop the capture

with the contents of the capture you should see that all port 137 
connection attempts come immediately after an init. sequence of either a 
web browser or other update software. If however, it is a bot or some 
trojan, you should see far more traffic than that of what you are 
generating, and in this case, clear your zone alarm settings and watch 
which application is trying to make the requests.



Thanks,
Ryan Yagatich  <support () pantek com>
        Pantek, Incorporated
 (877) LINUX-FIX - (440) 519-1802
  http://www.pantek.com/library/
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 A formal parsing algorithm should
 not always be used. -- D. Gries


On Fri, 22 Nov 2002, Moshe Aelion wrote:

> HC
>
> Referring to parts of your message:
>
> > "However, the fact that your system is responding would be indicative of
> something else, possibly w/ your ZA installation".
> What do you mean by that, and how can I confirm/disprove it?
>
> > Also, since your logs don't show an ICMP port unreachable response (your
> system sent out a UDP datagram), that would indicate that, in fact, >the
> source IPs are NOT spoofed.
> The source addresses are completely random, and they turn up absolutely
> nothing in a  reverse resolution and WHOIS queries. In fact, this is
> happening only with the source IP addresses of the probes to which the PC is
> trying to respond; the other probes, ignored by the PC, have a resolved host
> name (you can see it in the ZA log attached). I think this is very
> suspicious - in fact, it's a pretty unique and discernible behavior - is
> anyone familiar with a bot/Trojan behaving this way?
>
> > Is there anything besides the traffic you posted that would lead you to
> believe that you had something installed on your system?
> Like I mentioned above: 1. The immediate response attempt to the probe; and
> 2. The fact that when the Internet is on-line, the explorer and svchost
> processes are constantly active, with I/O of 25-30 kbps. This ceases when I
> go off-line.
>
> Is this behavior similar to any known bot infection?
>
> Thanks in advance
>
> Moshe
>
>
> ---------------------------------- Original
> Message ----- ----------------------------------------
> From: H C
> To: incidents () securityfocus com
> Sent: Saturday, November 16, 2002 3:10 PM
> Subject: re: Help - a possible bot
>
>
> > The problem is, I am detecting a suspicious
> hit/respond
> > activity, which, in my opinion, points to an active
> > bot.
>
> No offense, dude, but you're freaking out over
> nothing.  Based on the information you provided, there
> IS no bot (remember "The Matrix"?  "There is no
> spoon").
>
> > Here's the evidence: when inspecting ZA logs, you
> can
> > see a blocked scan (coming every couple of minutes,
> > from arbitrary addresses
>
> The "scans" you're referring to look like NetBIOS name
> scans...queries to UDP port 137.  On normal MS
> networks, these "scans" would originate from UDP port
> 137, as well.  So...they MAY be scans of some kind.
> However, the fact that your system is responding would
> be indicative of something else, possibly w/ your ZA
> installation.
>
> > - I bet they're spoofed
>
> Well, that's not "evidence", now, is it?  Also, since
> your logs don't show an ICMP port unreachable response
> (your system sent out a UDP datagram), that would
> indicate that, in fact, the source IPs are NOT
> spoofed.
>
> Also, there's nothing in the netstat and fport outputs
> that you sent that seem to indicate that you have any
> sort of bot or trojan at all.  Is there anything
> besides the traffic you posted that would lead you to
> believe that you had something installed on your
> system?
>
> HTH
>
>
>
>
>
>
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