Security Incidents mailing list archives
Re: Help - a possible bot
From: Ryan Yagatich <ryany () pantek com>
Date: Tue, 26 Nov 2002 09:52:36 -0500 (EST)
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/ =================================== E4 8B F0 68 9E 4F 34 9D 23 7D 62 1C EA AD 45 E3 C3 13 A9 9D BB 8B A1 6F =================================== 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 ofsomething 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 (yoursystem 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 tobelieve 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 botThe problem is, I am detecting a suspicioushit/respondactivity, 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, youcansee a blocked scan (coming every couple of minutes, from arbitrary addressesThe "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 spoofedWell, 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 __________________________________________________ Do you Yahoo!? Yahoo! Web Hosting - Let the expert host your site http://webhosting.yahoo.com ---------------------------------------------------------------------------- This list is provided by the SecurityFocus ARIS analyzer service. For more information on this free incident handling, management and tracking system please see: http://aris.securityfocus.com
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Current thread:
- re: Help - a possible bot H C (Nov 17)
- Re: Help - a possible bot Moshe Aelion (Nov 25)
- Re: Help - a possible bot Ryan Yagatich (Nov 26)
- <Possible follow-ups>
- RE: Help - a possible bot Dan Perez (Nov 17)
- Re: Help - a possible bot Nick FitzGerald (Nov 17)
- Re: Help - a possible bot Emeric Miszti (Nov 17)
- Re: Help - a possible bot Moshe Aelion (Nov 25)
- Re: Help - a possible bot Jon Nelson (Nov 17)
- Re: Help - a possible bot Mally Mclane (Nov 19)
- Re: Help - a possible bot Moshe Aelion (Nov 25)