Suspicious Inbound/Outbound traffic

dimitris.kalamaras · 04-03-2006, 03:03 PM

I am running a lan with the LinkSys WAG354G router as gateway and two PCs w/ Fedora Core 5.

I keep on getting the following messages in the security log of LinkSys:
2006-04-02T22:48:51+02:00 Hacker Attack TCP: From: 82.153.107.181:2988 To: 62.1.240.68:32459
2006-04-02T22:48:53+02:00 Hacker Attack TCP: From: 81.111.74.137:55906 To: 62.1.240.68:32459
2006-04-02T22:48:54+02:00 Hacker Attack TCP: From: 87.110.24.86:1959 To: 62.1.240.68:32459
2006-04-02T22:57:10+02:00 Hacker Attack TCP: From: 74.56.111.232:61924 To: 62.1.240.68:32459
2006-04-02T23:00:31+02:00 Hacker Attack TCP: From: 81.10.107.103:1935 To: 62.1.240.68:32459
2006-04-02T23:00:32+02:00 Hacker Attack TCP: From: 83.28.10.214:1684 To: 62.1.240.68:32459
2006-04-02T23:00:35+02:00 Hacker Attack TCP: From: 81.111.74.137:61685 To: 62.1.240.68:32459
2006-04-02T23:02:07+02:00 Hacker Attack TCP: From: 24.52.96.167:3335 To: 62.1.240.68:32459

Is this an attack? Why all these are targeting port 32459? BTW, I do not run any torrent client.

Second, the router reports my computer (192.168.1.64) as sending UDP packets from sequential ports, i.e.

2006-04-02T17:06:15+02:00 UDP: From: 192.168.1.64:33184 To: 193.92.150.3:53
2006-04-02T17:06:20+02:00 UDP: From: 192.168.1.64:33185 To: 194.219.227.2:53
2006-04-02T17:06:29+02:00 UDP: From: 192.168.1.64:33184 To: 193.92.150.3:53
2006-04-02T17:06:40+02:00 UDP: From: 192.168.1.64:33187 To: 193.92.150.3:53
2006-04-02T17:06:45+02:00 UDP: From: 192.168.1.64:33188 To: 194.219.227.2:53
2006-04-02T17:06:54+02:00 UDP: From: 192.168.1.64:33187 To: 193.92.150.3:53
2006-04-02T17:07:04+02:00 UDP: From: 192.168.1.64:33189 To: 193.92.150.3:53
2006-04-02T17:07:06+02:00 TCP: From: 192.168.1.64:54558 To: 193.0.0.135:43
2006-04-02T17:08:40+02:00 TCP: From: 192.168.1.64:49886 To: 193.0.0.135:43
2006-04-02T17:09:40+02:00 TCP: From: 192.168.1.64:49935 To: 193.0.0.135:43
2006-04-02T17:10:09+02:00 TCP: From: 192.168.1.64:60514 To: 64.34.165.170:80
2006-04-02T17:10:10+02:00 TCP: From: 192.168.1.64:60516 To: 64.34.165.170:80
2006-04-02T17:10:10+02:00 TCP: From: 192.168.1.64:59665 To: 152.3.183.74:80
2006-04-02T17:10:10+02:00 TCP: From: 192.168.1.64:60527 To: 64.34.165.170:80
2006-04-02T17:10:11+02:00 TCP: From: 192.168.1.64:59667 To: 152.3.183.74:80
2006-04-02T17:10:12+02:00 TCP: From: 192.168.1.64:60529 To: 64.34.165.170:80
2006-04-02T17:10:12+02:00 TCP: From: 192.168.1.64:60530 To: 64.34.165.170:80

Does this means that the computer is hacked? Any suggestions where to look?

JakeX · 04-03-2006, 03:37 PM

Looks like uTorrent traffic for port 32459, if this helps:
http://isc.sans.org/port_details.php?port=32459

Even tho you said you don't have a bittorrent client running. It looks typical of bittorrent logging..

int0x80 · 04-03-2006, 04:09 PM

Post some tcpdump output with packet headers.

Brian1 · 04-03-2006, 04:32 PM

One of the ips is to a webmail page. http://64.34.165.170/:80 goto http sites.

Brian1

dimitris.kalamaras · 04-03-2006, 05:14 PM

OK. I think I found the outbound part. Stupid me! The addresses w/ port 53 were dynamically assigned DNS servers from my ISP. So when I was asking for a web page the router was contacting the DNS for info. It seems reasonable, don't you think?

But the first part is still a mystery to me. Why I keep on getting TCP packets to a torrent port although I do not use torrent?

nx5000 · 04-04-2006, 09:30 AM

If you have a dynamic ip maybe you are taking the ip of a person who before you was doing bittorent with this IP. And the time that the bittorent removes you from good sources you will still receive questions from others. I don't know bittorent so I don't know the mechanism.
In this case, what I do is restart my router (and wait >5mn) so that I am assigned a new IP.
In a way, as your firewall is blocking the port (you're not saying : the port is open/closed, you're not answering anything which is not standard), the other clients will try again. You could open the port on your firewall..

For the rest of the traffic, it looks like some DNS or some webserver are longer to answer that the timeout of your firewall (good values can be 15mn for TCP,40s for UDP if you can modify them)

And these kind of logs are pretty useless because as int0x80 said you would need the complete headers which you probably can't have from the webconsole of your router.

You could also get a kernel >= 2.6.15 it has some more network security features.