Omri Herscovici: CapTipper - Malicious HTTP traffic explorer tool

What is CapTipper

CapTipper is a python tool to analyze, explore and revive HTTP malicious traffic.
CapTipper sets up a web server that acts exactly as the server in the PCAP file,
and contains internal tools, with a powerful interactive console, for analysis and inspection of the hosts, objects and conversations found.

The tool provides the security researcher with easy access to the files and the understanding of the network flow,
and is useful when trying to research exploits, pre-conditions, versions, obfuscations, plugins and shellcodes.

Feeding CapTipper with a drive-by traffic capture (e.g of an exploit kit) displays the user with the requests URI's that were sent and responses meta-data.
The user can at this point browse to http://127.0.0.1/[URI] and receive the response back to the browser.
In addition, an interactive shell is launched for deeper investigation using various commands such as: hosts, hexdump, info, ungzip, body, client, dump and more...

Analysis Example

Usage: ./CapTipper.py <PCAP_file> [web_server_port=80]

Let's analyze the following Nuclear EK drive-by infection PCAP 2014-11-06-Nuclear-EK-traffic.pcap

C:\CapTipper> CapTipper.py "C:\NuclearFiles\2014-11-06-Nuclear-EK-traffic.pcap"

CapTipper v0.1 - Malicious HTTP traffic explorer tool
Copyright 2015 Omri Herscovici <omriher@gmail.com>

[A] Analyzing PCAP: C:\NuclearFiles\2014-11-06-Nuclear-EK-traffic.pcap

[+] Traffic Activity Time: Thu, 11/06/14 17:02:35
[+] Conversations Found:

0: / -> text/html (0.html) [5509 B]
1: /wp-includes/js/jquery/jquery.js?ver=1.7.2 -> application/javascript (jquery.js) [39562 B]
2: /seedadmin17.html -> text/html (seedadmin17.html) [354 B]
3: /15c0b14drr9f_1_08282d03fb0251bbd75ff6dc6e317bd9.html -> text/html (15c0b14drr9f_1_08282d03fb0251bbd75ff6dc6e317bd9.html) [113149 B]
4: /wp-content/uploads/2014/01/MetroWest_COVER_Issue2_Feb2014.jpg -> image/jpeg (MetroWest_COVER_Issue2_Feb2014.jpg) [350008 B]
5: /images/footer/3000melbourne.png -> image/png (3000melbourne.png) [2965 B]
6: /images/footer/3207portmelbourne.png -> image/png (3207portmelbourne.png) [3092 B]
7: /wp-content/uploads/2012/09/background1.jpg -> image/jpeg (background1.jpg) [33112 B]
8: /00015d76d9b2rr9f/1415286120 -> application/octet-stream (00015d76.swf) [31579 B]
9: /00015d766423rr9f/1415286120 -> application/pdf (XykpdWhZZ2.pdf) [9940 B]
10: /00015d76rr9f/1415286120/5/x00809070554515d565b010b03510053535c0505;1;6 -> application/octet-stream (5.exe) [139264 B]
11: /00015d76rr9f/1415286120/5/x00809070554515d565b010b03510053535c0505;1;6;1 -> application/octet-stream (5.exe) [139264 B]
12: /00015d76rr9f/1415286120/7 -> application/octet-stream (7.exe) [139264 B]
13: /00015d761709rr9f/1415286120 -> application/octet-stream (00015d76.swf) [8064 B]
14: /00015d76rr9f/1415286120/8 -> application/octet-stream (8.exe) [139264 B]

[+] Started Web Server on http://localhost:80
[+] Listening to requests...

CapTipper Interpreter
Type 'open <conversation id>' to open address in browser
Type 'hosts' to view traffic flow
Type 'help' for more options

CT>

The Initialization outputs the conversations found between the client and the server in the following format:

[ID] : REQUEST URI -> SERVER RESPONSE TYPE (FILENAME) [SIZE IN BYTES]

ID: An assigned Id to the specific conversation
REQUEST URI: The URI that was sent to the server in the GET request
SERVER RESPONSE TYPE: The content-type returned in the server response header
FILENAME: The filename can be a few things:
1) Filename attribute given in the response header
2) Derived from the URI
3) Assigned by CapTipper if couldn't find any of the above
SIZE IN BYTES: Response body size

After Initalization, 2 things occur:

CapTipper creates a pseudo-web server that behaves like the web server in the pcap
An Interpreter is launched

The interpreter contains internal tools for further investigation of the objects in the pcap.
Opening a URI in the browser is simply by typing 'open' along with the object id

CT> open 0
CT> log
[2015-01-09T18:01:28.878000] 127.0.0.1 : GET / HTTP/1.1

None of the commands (Except 'open') actually requires the server to be running.
You can turn off the server by typing 'server off' or by adding -s when calling CapTipper.

Let's see what can we find out without using the browser.

First, we'll take a bird's-eye view on the traffic by using the command 'hosts'

CT> hosts
Found Hosts:
www.magmedia.com.au
├-- / [0]
├-- /wp-includes/js/jquery/jquery.js?ver=1.7.2 [1]
├-- /wp-content/uploads/2014/01/MetroWest_COVER_Issue2_Feb2014.jpg [4]
├-- /images/footer/3000melbourne.png [5]
├-- /images/footer/3207portmelbourne.png [6]
└-- /wp-content/uploads/2012/09/background1.jpg [7]

pixeltouchstudios.tk
└-- /seedadmin17.html [2]

grannityrektonaver.co.vu
├-- /15c0b14drr9f_1_08282d03fb0251bbd75ff6dc6e317bd9.html [3]
├-- /00015d76d9b2rr9f/1415286120 [8]
├-- /00015d766423rr9f/1415286120 [9]
├-- /00015d76rr9f/1415286120/5/x00809070554515d565b010b03510053535c0505;1;6 [10]
├-- /00015d76rr9f/1415286120/5/x00809070554515d565b010b03510053535c0505;1;6;1 [11]
├-- /00015d76rr9f/1415286120/7 [12]
├-- /00015d761709rr9f/1415286120 [13]
└-- /00015d76rr9f/1415286120/8 [14]

It seems that www.magmedia.com.au is the compromised site.

By crossing this information and the file types we got in the conversations list, it looks like grannityrektonaver.co.vu is the infecting host.

Then what is pixeltouchstudios.tk ?

Well, knowing how exploit-kits usually work, this is probably the TDS (Traffic Distribution System) server.
Let's take a closer look.

We can print the header and the body of the page by typing 'head' and 'body':

CT> head 2
Displaying header of object 2 (seedadmin17.html):

HTTP/1.1 302 Found
Server: nginx
Date: Thu, 06 Nov 2014 15:02:38 GMT
Content-Type: text/html; charset=iso-8859-1
Content-Length: 354
Connection: keep-alive
Set-Cookie: ehihm=_YocADE3AAIAAgCvjVtU__.vjVtUQAABAAAAr41bVAA-; expires=Fri, 06-Nov-2015 15:03:11 GMT; path=/; domain=pixeltouchstudios.tk
Location: http://grannityrektonaver.co.vu/15c0b14drr9f_1_08282d03fb0251bbd75ff6dc6e317bd9.html

CT> body 2
Displaying body of object 2 (seedadmin17.html) [256 bytes]:

<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
<html><head>
<title>302 Found</title>
</head><body>
<h1>Found</h1>
<p>The document has moved <a href="http://grannityrektonaver.co.vu/15c0b14drr9f_1_08282d03fb0251bbd75ff6dc6e317bd9.html">here</a>.</p>
<hr

By deafult, the body command returns the first 256 byte, you can change it by typing body 2 1000 - this will print the first 1000 bytes

We see that object 2, returns a 302 redirection to the infecting host.
So our hypothesis was probably true.

Let's get more information on object 2 by typing 'info':

CT> info 2
Info of conversation 2:

SERVER IP : 108.61.196.84:80
HOST : pixeltouchstudios.tk
URI : /seedadmin17.html
REFERER : http://www.magmedia.com.au/
RESULT NUM : 302 Found
RESULT TYPE : text/html
FILE NAME : seedadmin17.html
LENGTH : 354 B

The referrer to that page was of course magmedia.co.au, but what exactly redirected us?

By looking at the conversations it was probably either the index page or the javascript file.
Let's have a quick peek at the javascript file (object 1)

CT> body 1
Displaying body of object 1 (jquery.js) [256 bytes]:

▼ ♦♥─╜i{#╟ס╢√}~♣X╓t♥═"HJצg♀░→o½%Y▓╡ם║m┘CR║ @a!▒P ╪כ ╬o?≈‼╣TJ≥£≈\g╞jó╢\"#cן╚πg ÷ry≤~5↔O6םµ╦Vπ├ףף h|╛*ך╞½σh≤6_§ם╧ק╖כa╛ש.↨iπ╦┼á▌רl67¥ππ╤z╘^«╞╟ ÷∞°▀F╖כב▐hלכ═╦σ≥zZ4≤╓▌¢|╒Φg├σαv^,6φב=h╧≤═`╥\¶o ←▀↨π╧▐▌4ףf»≤π╢█h%חy{U▄╠≥A╤

Hmm... What's going on? Let's look at the header

CT> head 1
Displaying header of object 1 (jquery.js):

HTTP/1.1 200 OK
Content-Encoding: gzip
Vary: Accept-Encoding
Date: Thu, 06 Nov 2014 15:03:41 GMT
Server: LiteSpeed
Accept-Ranges: bytes
Connection: Keep-Alive
Keep-Alive: timeout=5, max=100
Last-Modified: Mon, 10 Feb 2014 12:34:10 GMT
Content-Type: application/javascript
Content-Length: 39562
Cache-Control: public, max-age=604800
Expires: Thu, 13 Nov 2014 15:03:41 GMT

The response is gzipped.
Let's ungzip it:

CT> ungzip 1
GZIP Decompression of object 1 (jquery.js) successful!
New object created: 15

Great. a new object was created (15).
Let's look at it.

CT> body 15
Displaying body of object 15 (ungzip-jquery.js) [256 bytes]:

/*
Copyright (C) 2007 Free Software Foundation, Inc. http://fsf.org/
*/
function getCookie(a){var b=document.cookie.match(new RegExp("(?:^|; )"+a.replace(/([\.$?*|{}\[\]\\\/\+^])/g,"\\$1")+"=([^;]*)"));return b?decodeU
RIComponent(b[1]):undefined}(funct

So this is the ungzipped version of the JS file.
Remember, we want to find out what redirected us to the TDS,
Safe to assume it was an iframe, so let's search for iframes in the new object using the command 'iframes'

CT> iframes 15
Searching for iframes in object 15 (ungzip-jquery.js)...
1 Iframe(s) Found!

[I] 1 : http://pixeltouchstudios.tk/seedadmin17.html

There you go, the attacker planted/altered this javascript and made it send the users to the TDS.

Now let's take a look at the files from the infecting server.
typing 'convs' again will display the conversations:

CT> convs
Conversations Found:

0: / -> text/html (0.html) [5509 B]
1: /wp-includes/js/jquery/jquery.js?ver=1.7.2 -> application/javascript (jquery.js) [39562 B]
2: /seedadmin17.html -> text/html (seedadmin17.html) [354 B]
3: /15c0b14drr9f_1_08282d03fb0251bbd75ff6dc6e317bd9.html -> text/html (15c0b14drr9f_1_08282d03fb0251bbd75ff6dc6e317bd9.html) [113149 B]
4: /wp-content/uploads/2014/01/MetroWest_COVER_Issue2_Feb2014.jpg -> image/jpeg (MetroWest_COVER_Issue2_Feb2014.jpg) [350008 B]
5: /images/footer/3000melbourne.png -> image/png (3000melbourne.png) [2965 B]
6: /images/footer/3207portmelbourne.png -> image/png (3207portmelbourne.png) [3092 B]
7: /wp-content/uploads/2012/09/background1.jpg -> image/jpeg (background1.jpg) [33112 B]
8: /00015d76d9b2rr9f/1415286120 -> application/octet-stream (00015d76.swf) [31579 B]
9: /00015d766423rr9f/1415286120 -> application/pdf (XykpdWhZZ2.pdf) [9940 B]
10: /00015d76rr9f/1415286120/5/x00809070554515d565b010b03510053535c0505;1;6 -> application/octet-stream (5.exe) [139264 B]
11: /00015d76rr9f/1415286120/5/x00809070554515d565b010b03510053535c0505;1;6;1 -> application/octet-stream (5.exe) [139264 B]
12: /00015d76rr9f/1415286120/7 -> application/octet-stream (7.exe) [139264 B]
13: /00015d761709rr9f/1415286120 -> application/octet-stream (00015d76.swf) [8064 B]
14: /00015d76rr9f/1415286120/8 -> application/octet-stream (8.exe) [139264 B]

So what do we have here...
looks like we have 1 PDF file, 2 SWF files, and 4 EXE files that were probably downloaded by the shellcode.

We can dump all the files to a folder for deeper inspection using the 'dump' function, we can add '-e' to refrain from dumping the EXE files, so we won't accidentally launch them.

CT> dump all c:\NuclearFiles -e
Object 0 written to c:\NuclearFiles\0-0.html
Object 1 written to c:\NuclearFiles\1-jquery.js
Object 2 written to c:\NuclearFiles\2-seedadmin17.html
Object 3 written to c:\NuclearFiles\3-15c0b14drr9f_1_08282d03fb0251bbd75ff6dc6e317bd9.html
Object 4 written to c:\NuclearFiles\4-MetroWest_COVER_Issue2_Feb2014.jpg
Object 5 written to c:\NuclearFiles\5-3000melbourne.png
Object 6 written to c:\NuclearFiles\6-3207portmelbourne.png
Object 7 written to c:\NuclearFiles\7-background1.jpg
Object 8 written to c:\NuclearFiles\8-00015d76.swf
Object 9 written to c:\NuclearFiles\9-XykpdWhZZ2.pdf
Object 13 written to c:\NuclearFiles\13-00015d76.swf
Object 15 written to c:\NuclearFiles\15-ungzip-jquery.js

As you can see, it also dumps the newly created ungzipped javascript file.

We can also examing the files using CapTipper.
Let's take a look at the first SWF file using 'hexdump'.

CT> hexdump 8
Displaying hexdump of object 8 (00015d76.swf) body [256 bytes]:

0000 5A 57 53 17 E4 1B 01 01 4A 7B 00 00 5D 00 00 00 ZWS.....J{..]...
0010 01 00 3B FF FC 8E 19 FA DF E7 66 08 A0 3D 3E 85 ..;.......f..=>.
0020 F5 75 6F D2 74 6B 7F 7F 31 2C 92 04 FD 10 0A EE .uo.tk..1,......
0030 E2 C5 C2 C9 4C 83 91 74 AE C8 7C 80 F6 31 A6 CE ....L..t..|..1..
0040 C0 15 CB 62 8D 76 42 8B 28 96 D3 83 FE 20 DE 57 ...b.vB.(.... .W
0050 7B E4 D2 F1 D8 BC E6 45 CF DC 7B 79 38 41 60 1F {......E..{y8A`.
0060 0A E9 E4 10 8B F8 DA 0D A6 32 CF E1 E6 E9 78 AB .........2....x.
0070 8B A7 8A C5 62 8F 0B 31 84 41 10 75 B1 33 35 9D ....b..1.A.u.35.
0080 6E BA 30 B8 AE EB 78 33 31 67 36 42 01 36 4A A3 n.0...x31g6B.6J.
0090 C8 CB 29 B5 36 6E BF A7 D2 3B 9F 5C 6B A8 4A 9F ..).6n...;.\k.J.
00A0 A5 59 5F 7F 43 98 39 43 E8 90 69 C7 9D 84 3A 9C .Y_.C.9C..i...:.
00B0 36 1D E6 12 F8 EB 03 EA F4 59 2A FD 71 9F 15 DB 6........Y*.q...
00C0 4B F3 C3 C4 4C 70 11 A1 19 25 C8 79 6E 4A 5E 4C K...Lp...%.ynJ^L
00D0 10 F5 A2 F9 1A E0 18 42 9D 87 9D 39 12 39 57 89 .......B...9.9W.
00E0 CF EF 41 78 2E 57 88 C9 A5 BA F2 0E FC E0 5E B5 ..Ax.W........^.
00F0 66 0C B4 7E A2 0B C4 D7 65 F8 12 57 98 58 16 16 f..~....e..W.X..

Now let's take a look at the second one:

CT> hexdump 13
Displaying hexdump of object 13 (00015d76.swf) body [256 bytes]:

0000 50 4B 03 04 14 00 00 08 08 00 81 7A 5D 45 6F 8B PK.........z]Eo.
0010 BE 6C D2 00 00 00 6B 01 00 00 10 00 00 00 41 70 .l....k.......Ap
0020 70 4D 61 6E 69 66 65 73 74 2E 78 61 6D 6C 85 8F pManifest.xaml..
0030 C1 4A 03 31 10 86 EF 42 DF 21 E4 01 92 50 6A 95 .J.1...B.!...Pj.
0040 C5 2D 14 F4 2A A5 8A F7 98 9D DA 60 66 12 32 69 .-..*......`f.2i
0050 9B 7D 36 0F 3E 92 AF E0 D6 A2 EC 61 C1 EB 37 FF .}6.>......a..7.
0060 C7 C7 7C 7D 7C DE DD 43 0A B1 47 A0 22 2A 06 E2 ..|}|..C..G."*..
0070 56 EE 4B 49 8D D6 EC F6 80 96 15 7A 97 23 C7 5D V.KI.......z.#.]
0080 51 2E A2 76 C1 0F 53 3D 37 E6 46 77 7F AA BC B8 Q..v..S=7.Fw....
0090 4D FD C7 3E 79 DA D5 B3 BC D4 D5 62 90 E2 81 4A M..>y......b...J
00A0 EE 37 D1 53 59 33 03 BE 86 BE 95 15 F2 D1 A2 25 .7.SY3.........%
00B0 48 B0 00 7A F7 E3 D5 73 9F A0 95 96 BB 37 EE D4 H..z...s.....7..
00C0 3A 25 29 B6 07 2A 1E E1 05 32 FB 48 AD 5C 28 A3 :%)..*...2.H.\(.
00D0 AE CD ED 7C A9 8C 5C CD AE 84 18 7D A8 36 36 17 ...|..\....}.66.
00E0 FE A1 03 FF 2D 9E A1 A8 CD A3 45 98 8A 3F C5 43 ....-.....E..?.C
00F0 76 13 17 D5 85 E1 01 7D 69 E8 89 C8 18 AE BE 01 v......}i.......

Interesting... This file starts with the 'PK' magic bytes, meaning it's actually a zip file, which can be a few things.

Let's take a look at the files inside the zip using the command 'ziplist'

CT> ziplist 13
2 Files found in zip object 13 (00015d76.swf):

[Z] 1 : AppManifest.xaml
[Z] 2 : xervamanepe4enki.dll

Well it seems that this is actually a Silverlight exploit.
Now we can dump it with it's real extension:

CT> dump 13 c:\NuclearFiles\Silver_exp.xap
Object 13 written to c:\NuclearFiles\Silver_exp.xap

We can also send the file's md5 hash to VirusTotal to see if it is recognized by any of the Anti-Virus providers, using the command 'vt'.
These requires a VirusTotal public API key.
(The file itself isn't sent to VT, only the hash of the file is sent!)

CT> vt 13
VirusTotal result for object 13 (00015d76.swf):

Detection: 37/56
Last Analysis Date: 2014-12-11 13:15:33
Report Link: https://www.virustotal.com/file/5bcb20f506ce854eb3191ca87a14c5777cdcb0f96ffec0b6...

Scan Result:
MicroWorld-eScan Trojan.GenericKD.1962112 12.0.250.0 20141211
nProtect Trojan.GenericKD.1962112 2014-12-11.01 20141211
CAT-QuickHeal Trojan.Generic.r3 14.00 20141210
McAfee RDN/Generic Exploit!1ns 6.0.5.614 20141211
Malwarebytes Trojan.Agent 1.75.0.1 20141211
VIPRE Trojan.Win32.Generic!BT 35624 20141211
K7AntiVirus Exploit ( 004b06661 ) 9.186.14309 20141211
K7GW Exploit ( 004b06661 ) 9.186.14308 20141211
Agnitum Exploit.CVE-2013-0074! 5.5.1.3 20141210
F-Prot W32/CVE130074.I 4.7.1.166 20141211
Symantec Trojan.Gen.2 20141.1.0.330 20141211
Norman CVE-2013-0074.D 7.04.04 20141211
TotalDefense Win32/Tnega.DPSQOR 37.0.11324 20141211
TrendMicro-HouseCall Suspicious_GEN.F47V1112 9.700.0.1001 20141211
Avast Win32:Malware-gen 8.0.1489.320 20141211
ClamAV SILVERLIGHT.Exploit.Nuclear 0.98.5.0 20141211
BitDefender Trojan.GenericKD.1962112 7.2 20141211
NANO-Antivirus Exploit.Win32.CVE20130074.dikfyh 0.28.6.63850 20141211
Ad-Aware Trojan.GenericKD.1962112 12.0.163.0 20141211
Sophos Mal/Generic-S 4.98.0 20141211
Comodo UnclassifiedMalware 20333 20141211
F-Secure Trojan.GenericKD.1962112 11.0.19100.45 20141211
DrWeb Exploit.CVE2013-0074.36 7.0.10.8210 20141211
McAfee-GW-Edition RDN/Generic Exploit!1ns v2014.2 20141211
Emsisoft Trojan.GenericKD.1962112 (B) 3.0.0.600 20141211
Cyren W32/CVE130074.MCZQ-2806 5.4.1.7 20141211
Avira EXP/Silverlight.Gen2 7.11.194.74 20141211
Antiy-AVL Trojan/Win32.SGeneric 1.0.0.1 20141211
Microsoft Exploit:MSIL/CVE-2013-0074.F 1.11202 20141211
GData Trojan.GenericKD.1962112 24 20141211
ALYac Exploit.CVE-2013-0074 1.0.1.4 20141211
AVware Trojan.Win32.Generic!BT 1.5.0.21 20141211
Panda Exploit/CVE-2013-0074 4.6.4.2 20141211
ESET-NOD32 a variant of Win32/Exploit.CVE-2013-0074.BZ 10861 20141211
Ikarus Exploit.CVE-2013-0074 T3.1.8.5.0 20141211
AVG Exploit_c.ABKR 15.0.0.4235 20141211
Baidu-International Trojan.Win32.CVE-2013-0074.bBZ 3.5.1.41473 20141211

We notice that most of the Anti-Viruses detected this file as malicious, while some even provided the exploit CVE (2013-0074)

If you don't have a VirusTotal public API key, you can use the command 'hashes', and manually send the hash to VirusTotal.

Info

CapTipper was written by Omri Herscovici
Twitter: @omriher

Please open an issue for bugs.
I would be happy to accept suggestions and feedback to my mail :)

To do (Added among other things to CapTipper v0.2):

~~File Identification~~

~~Regex Search~~

~~PE info~~

omriher@gmail.com

CapTipper can be found at GitHub: https://github.com/omriher/CapTipper

Omri Herscovici

Tuesday, January 13, 2015

CapTipper - Malicious HTTP traffic explorer tool

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