Possible form for a ddos attack?

Question

I have kinda asked this before. I've set up a server that serves my website, dns and some gameservers. However, when I check my routers firewall log, I get alot of incoming UDP packets blocked on the same port. This is how it looks like, notice that the ports are not the normal and it's not opened or used.

    [INFO] Sat Aug 25 21:25:09 2012 Blocked incoming UDP packet from 176.212.55.166:49001 to 84.234.160.79:61767
[INFO] Sat Aug 25 21:25:05 2012 Blocked incoming UDP packet from 186.227.20.17:21401 to 84.234.160.79:14953
[INFO] Sat Aug 25 21:25:05 2012 Blocked incoming UDP packet from 117.203.8.239:14090 to 84.234.160.79:14953
[INFO] Sat Aug 25 21:25:03 2012 Blocked incoming UDP packet from 77.35.1.215:49001 to 84.234.160.79:14953
[INFO] Sat Aug 25 21:24:53 2012 Blocked incoming UDP packet from 90.180.165.121:10011 to 84.234.160.79:61767
[INFO] Sat Aug 25 21:24:51 2012 Blocked incoming UDP packet from 190.51.167.28:22486 to 84.234.160.79:14953
[INFO] Sat Aug 25 21:24:45 2012 Blocked incoming UDP packet from 159.224.93.23:25946 to 84.234.160.79:14953
[INFO] Sat Aug 25 21:24:44 2012 Blocked incoming UDP packet from 176.212.55.166:49001 to 84.234.160.79:61767
[INFO] Sat Aug 25 21:24:43 2012 Blocked incoming UDP packet from 62.63.214.200:62348 to 84.234.160.79:61767
[INFO] Sat Aug 25 21:24:40 2012 Blocked incoming UDP packet from 43.244.112.201:45811 to 84.234.160.79:14953
[INFO] Sat Aug 25 21:24:30 2012 Blocked incoming UDP packet from 78.8.169.255:1236 to 84.234.160.79:28018
[INFO] Sat Aug 25 21:24:30 2012 Blocked incoming UDP packet from 91.205.238.31:16672 to 84.234.160.79:14953
[INFO] Sat Aug 25 21:24:29 2012 Blocked incoming UDP packet from 176.212.55.166:49001 to 84.234.160.79:61767
[INFO] Sat Aug 25 21:24:19 2012 Blocked incoming UDP packet from 213.115.74.42:50839 to 84.234.160.79:61767
[INFO] Sat Aug 25 21:24:13 2012 Blocked incoming UDP packet from 142.68.127.231:40886 to 84.234.160.79:61767
[INFO] Sat Aug 25 21:24:09 2012 Blocked incoming UDP packet from 176.212.55.166:49001 to 84.234.160.79:61767
[INFO] Sat Aug 25 21:23:59 2012 Blocked incoming UDP packet from 87.14.231.178:21360 to 84.234.160.79:61767
[INFO] Sat Aug 25 21:23:56 2012 Blocked incoming UDP packet from 109.202.150.81:53385 to 84.234.160.79:28018
[INFO] Sat Aug 25 21:23:54 2012 Blocked incoming UDP packet from 83.183.5.227:53786 to 84.234.160.79:28015
[INFO] Sat Aug 25 21:23:53 2012 Blocked incoming UDP packet from 1.228.6.35:29826 to 84.234.160.79:14953
[INFO] Sat Aug 25 21:23:49 2012 Blocked incoming UDP packet from 176.212.55.166:49001 to 84.234.160.79:61767
[INFO] Sat Aug 25 21:23:42 2012 Blocked incoming UDP packet from 109.202.150.81:53371 to 84.234.160.79:28018
[INFO] Sat Aug 25 21:23:41 2012 Blocked incoming UDP packet from 84.90.108.176:49686 to 84.234.160.79:61767
[INFO] Sat Aug 25 21:23:39 2012 Blocked incoming UDP packet from 186.178.118.94:10063 to 84.234.160.79:61767
[INFO] Sat Aug 25 21:23:38 2012 Blocked incoming UDP packet from 217.122.204.212:41446 to 84.234.160.79:61767
[INFO] Sat Aug 25 21:23:36 2012 Blocked incoming UDP packet from 82.33.127.120:18441 to 84.234.160.79:61767
[INFO] Sat Aug 25 21:23:35 2012 Blocked incoming UDP packet from 81.19.46.234:1183 to 84.234.160.79:14953
[INFO] Sat Aug 25 21:23:33 2012 Blocked incoming UDP packet from 94.69.159.219:63959 to 84.234.160.79:61767
[INFO] Sat Aug 25 21:23:31 2012 Blocked incoming UDP packet from 83.68.239.193:21808 to 84.234.160.79:61767
[INFO] Sat Aug 25 21:23:29 2012 Blocked incoming UDP packet from 176.212.55.166:49001 to 84.234.160.79:61767
[INFO] Sat Aug 25 21:23:22 2012 Blocked incoming UDP packet from 109.202.150.81:53370 to 84.234.160.79:28018
[INFO] Sat Aug 25 21:23:21 2012 Blocked incoming UDP packet from 188.27.241.206:55403 to 84.234.160.79:61767
[INFO] Sat Aug 25 21:23:20 2012 Blocked incoming UDP packet from 189.24.110.248:61712 to 84.234.160.79:14953
[INFO] Sat Aug 25 21:23:13 2012 Blocked incoming UDP packet from 96.50.2.51:15432 to 84.234.160.79:61767
[INFO] Sat Aug 25 21:23:09 2012 Blocked incoming UDP packet from 176.212.55.166:49001 to 84.234.160.79:61767
[INFO] Sat Aug 25 21:23:03 2012 Blocked incoming UDP packet from 37.128.216.210:57785 to 84.234.160.79:28018
[INFO] Sat Aug 25 21:22:58 2012 Blocked incoming UDP packet from 115.37.98.215:24347 to 84.234.160.79:14953
[INFO] Sat Aug 25 21:22:50 2012 Blocked incoming UDP packet from 23.24.147.209:28970 to 84.234.160.79:61767
[INFO] Sat Aug 25 21:22:47 2012 Blocked incoming UDP packet from 86.11.74.217:45682 to 84.234.160.79:14953
[INFO] Sat Aug 25 21:22:46 2012 Blocked incoming UDP packet from 201.249.81.218:42176 to 84.234.160.79:61767
[INFO] Sat Aug 25 21:22:44 2012 Blocked incoming UDP packet from 176.212.55.166:49001 to 84.234.160.79:61767
[INFO] Sat Aug 25 21:22:41 2012 Blocked incoming UDP packet from 78.36.218.169:25903 to 84.234.160.79:14953
[INFO] Sat Aug 25 21:22:24 2012 Blocked incoming UDP packet from 176.212.55.166:49001 to 84.234.160.79:61767
[INFO] Sat Aug 25 21:22:21 2012 Blocked incoming TCP packet from 86.100.65.148:58771 to 84.234.160.79:80 as RST:ACK received but there is no active connection
[INFO] Sat Aug 25 21:22:21 2012 Blocked incoming TCP packet from 86.100.65.148:58775 to 84.234.160.79:80 as RST:ACK received but there is no active connection
[INFO] Sat Aug 25 21:22:21 2012 Blocked incoming TCP packet from 86.100.65.148:58776 to 84.234.160.79:80 as RST:ACK received but there is no active connection
[INFO] Sat Aug 25 21:22:21 2012 Blocked incoming TCP packet from 86.100.65.148:58777 to 84.234.160.79:80 as RST:ACK received but there is no active connection
[INFO] Sat Aug 25 21:22:21 2012 Blocked incoming TCP packet from 86.100.65.148:58769 to 84.234.160.79:80 as RST:ACK received but there is no active connection
[INFO] Sat Aug 25 21:22:19 2012 Blocked incoming UDP packet from 201.80.163.51:40668 to 84.234.160.79:61767

Notice the common ports that gets blocked is "61767" and they started using "14953". And it keeps comming, the log got more than this, so what should i do? The open ports for services is 1996:Remote desktop, 143:imap, 110:pop3, 25:smtp, 80:http, 443:https, 53:dns. And for the gameservers ort, I opened the range 27000-27900 As I use Srcds server for Team Fortress 2. So what should i do? It has kept comming since yesterday, and why? No idea.

Captured one UDP packet @ UDP 61767

00000000  64 31 3A 61 64 32 3A 69  64 32 30 3A 77 97 D9 57   d1:ad2:i d20:w..W 
00000010  FD 9B 37 AD 46 7A 55 32  C8 81 04 A7 36 D9 CE E1   ..7.FzU2 ....6... 
00000020  36 3A 74 61 72 67 65 74  32 30 3A 77 9D 1A BA E9   6:target 20:w.... 
00000030  FF 51 96 85 6E 0A 7C A6  FA 59 C0 69 40 37 36 65   .Q..n.|. .Y.i@76e 
00000040  31 3A 71 39 3A 66 69 6E  64 5F 6E 6F 64 65 31 3A   1:q9:fin d_node1: 
00000050  74 34 3A F2 0A 00 00 31  3A 76 34 3A 55 54 40 76   t4:....1 :v4:UT@v 
00000060  31 3A 79 31 3A 71 65                               1:y1:qe

Packet 2

00000000  64 31 3A 61 64 32 3A 69  64 32 30 3A A4 C6 64 B6   d1:ad2:i d20:..d. 
00000010  60 41 16 2E 34 E3 71 0F  34 4B DE 45 DB 27 BE E4   `A..4.q. 4K.E.'.. 
00000020  39 3A 69 6E 66 6F 5F 68  61 73 68 32 30 3A 77 9D   9:info_h ash20:w. 
00000030  1C A3 5B C9 67 67 97 1B  4D 4D D0 82 98 5F B8 6B   ..[.gg.. MM..._.k 
00000040  B2 7F 36 3A 6E 6F 73 65  65 64 69 31 65 36 3A 73   .6:nose edi1e6:s 
00000050  63 72 61 70 65 69 31 65  34 3A 77 61 6E 74 6C 32   crapei1e 4:wantl2 
00000060  3A 6E 34 32 3A 6E 36 65  65 31 3A 71 39 3A 67 65   :n42:n6e e1:q9:ge 
00000070  74 5F 70 65 65 72 73 31  3A 74 32 3A D8 B2 31 3A   t_peers1 :t2:..1: 
00000080  76 34 3A 5A 6F 00 06 31  3A 79 31 3A 71 65         v4:Zo..1 :y1:qe

Posted 02:24 am UTC + 01:00: It looks like it's over, so it's good when it stops.

That frankly doesn't look like a whole lot of traffic - is the volume of data actually causing you any problems? It's hard to tell what that traffic is from just that log - can you capture an example packet or two? `tcpdump -i eth0 -s 0 -w capture.pcap dst port 61767` — Shane Madden, Aug 25 '12 at 19:44
@ShaneMadden I have captured 2 UDP packets from the port 61767 and added it to the topic. — Teknikk, Aug 25 '12 at 19:54
If you didn't install a P2P client on that machine then it's a fair bet it has been compromised, in which case you need to nuke it and start again. — John Gardeniers, Aug 25 '12 at 22:30

Shane Madden · Accepted Answer · 2012-08-25T20:08:36.890

5

Looks like BitTorrent peer query traffic.

The system might be registered with a tracker - any chance that a BitTorrent client would have been run on the machine (or something behind it via NAT, perhaps)?

By the way, the hash of the file that your system is being asked for is in the second packet. I'll leave it as an exercise to the reader to find what file it was.

edited Aug 25 '12 at 20:08

answered Aug 25 '12 at 19:57

Shane Madden

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Possible form for a ddos attack?

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