TryHackMe | Simple CTF Box

Ready for another one? Let’s do it! As per usual, let’s do an nmap scan and see what’s going on.

Time to break it down:

  • Port 80: We can check for a site of some kind here in the web browser, and also look up the version of Apache to see if their are any vulnerabilities/exploits for it.
  • Same tactics can be applied to port 21 and port 2222, check the versions for vulnerabilities.

Personally, I like to start with the website in these instances, as you are usually guaranteed to have something there. The main page for this site is the default Apache page though, so let’s see if Dirbuster will give us any directories.

Let’s see what’s hiding in that /simple/ directory.

Pulling the site up shows us that the framework being used is “CMS Made Simple” version 2.2.8. Let’s see if there are any vulnerabilities for that.

Time to download and run the exploit:

The command I ran to get the output is the command below the output

Let’s break this command up a little bit:

  • “python” runs the exploit we downloaded as it is a .py file.
  • “46635.py” is the exploit file.
  • “-u” is referring to the target (basically). It is referring to the URL.
  • “–crack” says that you want to crack the passwords found and
  • “-w” is referring to the wordlist you want to use to crack the password

We found two usernames, here’s one of them:

Now that we cracked the password and have a username to attempt to use, let’s try out ssh’ing on port 2222.

Sweet! We made it in! Now we can take a look around.

There’s the user flag. Time to escalate privileges. The first step (especially in these beginner boxes) that I take is to perform the command “sudo -l”.

From there we are able to observe that vim can be run without the root password, so let’s check out GTFO Bins to see what we can do with vim.

Trying out the first option, it is a complete success! Let’s deconstruct why this works.

  • “sudo” runs program as superuser.
  • “NOPASSWD” in “sudo -l” means this user has the privilege level to run this program as the superuser without needing to authenticate.
  • “vim” the program we are running as the superuser.
  • “-c” designates a command to be read after the first file.
  • “‘:!/bin/sh'” is the command executed by the “-c” bit. It will run the shell as the elevated user, making you root.

That’s the end of it! Thanks for reading!

TryHackMe | RootMe Box

So, as per usual, let’s kick it off with an nmap scan:

We notice that two ports are open; 22-ssh, and 80-http. Web sites are always fun in CTFs and leave lots of different places to stuff clues and challenges, so let’s check out the site first, and run Dirbuster on it at the same time to see if it has any hidden directories.

Two important directories that are needed for us. /panel, and /uploads. Panel brings us to this page:

Which WILL NOT take a standard .php file (my poor reverse shell). And we can assume once we get past this roadblock, that the shell we will be executing is going to be located in the /uploads directory.

So I have a simple little minimalist reverse shell I like to use for php (nothing fancy, I should probably upgrade). I just need to run this command:

And switch it over to a php5 extension instead of php. This is called a “file name bypass” and hoodwinks the file name validation the upload functionality has in place. You can read further up on this here, but essentially, this is a type of blacklisting bypass. We found out that a php file is blacklisted from being uploaded, but to bypass this, we just have to try an unpopular php extension such as: php3, phpt, php5, php6, etc.

And wouldn’t ya know, it works! Let’s go verify that our reverse shell is now inside of the uploads directory.

Before clicking on it, make sure to get a netcat listener running.

You might have to do some things to stabilize this shell. As I said, it is extremely minimalist. Now we just need to search for a file with SUID permissions, and find the one that sticks out. We can do this by running the following command:

One major one that sticks out that I’ve used before can be seen here:

Python is great if you have access to it. Check out GTFO Bins for some more information. Keep in mind that this is SUID related, and we already have access to python.

That means we just need to run the second command there.

And boom, you’re root.

TryHackMe | Anthem Box

This box will be a little different, due to it being a Windows box. Now, given that like 98% of business infrastructure runs on Windows, I’m starting to think it’s due time for me to start branching out. I’ve got a couple more write ups coming soon, they are just very very long, so I haven’t gotten around to creating them yet.

But for this box, let’s start off with a little nmap scan.

So, we’ve got a lot of ports open. I’m going to look into the importance of each of these ports real quick, just for review:

  • Port 80 – HTTP: The port that the server expects to receive data from a web client. It can be configured differently, but this is the default.
  • Port 135 – MSRPC: This is a modified version of DCE/RPC. Stands for “Microsoft Remote Procedure Call”. It is a protocol that uses the client-server model in order to allow one program to request service from a program on another computer without having to understand the details of that computer’s network.
  • Port 139 – NetBIOS-SSN: Stands for “NETBIOS Session Service”. TCP NetBIOS connections are made over this port, usually by Windows machines, but can also be any other system running Samba (SMB). These sessions support “connection oriented file sharing activities”.
  • Port 445 – Microsoft-DS: This port is usually used for file sharing, with something like Samba. It stands for “Microsoft Directory Services”. It is the preferred port for carrying Windows file sharing and “numerous other services”.
  • Port 3389 – MS-WBT-Server: So, from the port number, we can already guess that this is an RDP instance. Also known as “msrdp” or “Microsoft Remote Display Protocol”, it sets up a terminal server that can be remoted into.

Let’s take a crack at the website first.

So, there wasn’t anything important on the main page, and robots.txt is always a great place to check when crawling directories. So if you’re feeling lazy and don’t want to start up and configure dirbuster, just add that “/robots.txt” to the end of the URL and see if it pulls up anything important. In our case it did, multiple directories to check out, and a potential password.

This just shows what the site’s URL is supposed to be. It answers one of the questions for the box.

Another question was to find out the name of the SysAdmin, which I considered this one a bit dumb, just because the whole concept of this question is flawed. You need to Google this poem that this employee wrote about the sysadmin, and it gives you the author of the original poem, which is what the sysadmin’s name is. Why this bears any relevance, how anyone was actually supposed to connect those dots, I’ll never know. I’m just glad I didn’t do the foot work on this bit of the box (haha).

^Name of the sysadmin^

This was to identify how the company creates its emails. So we have a first and last name, and we have an example email. Now we can create the sysadmin’s email, and it looks like we have his password from the robots.txt file too.

The challenge here was to just find three (maybe four? I don’t remember exactly) flags that were hidden in/on the site. Most of them were in the source code, so I just went to each page, opened the source code, and ctrl+f’d for “THM{“, which is the standard format for TryHackMe flags.

I didn’t spend too much time looking, but I feel like there should be a tool to crawl a specific website and all the links/pages it has on it and be able to look for certain parameters with the source code. I couldn’t find a tool like that, but maybe I should make one as a challenge. Could use Python + Beautiful Soup or something.

Final flag for this section was on a profile page.

I also broke into the website manager using the email and password for the sysadmin. Didn’t find anything, but it was fun to try.

So RDPing into the box works using the sysadmin and the password that we found. So now we just have to root around a bit (hehe…get it?), and then escalate our privilege to full admin to find the final text file.

First text file found just sitting on the desktop.

Interesting folders that were hidden. If going back through this box, you’ll want to check on those.

So, all we really had to do was add ourselves as owners to a hidden file, so that we now have full control.

Opening the file provides us with the administrator’s password.

Now, let’s log out, and attempt to login as admin.

And we’re in! The final flag was sitting on the desktop as well. Great box to get your feet wet with Windows and RDP, but I’m definitely looking forward to more!

TryHackMe | Bounty Hunter Box

TryHackMe has a box called “Bounty Hunter” which was a ton of fun, and definitely an experience. Let’s dive right into it.

I started off with a regular old nmap scan of the IP. It showed that there were three ports open, and so that means three potential points of entry. Now, before we start testing everything, we’d usually try to grab the versions of the software running on this ports, to make sure there is no blatantly obvious vulnerability. SSH ended up being up to date, so we’ll follow my normal approach for this type of situation. Which is immediately looking into FTP.

The most common thing that occurs for these beginner level boxes is that the FTP login is left to be anonymous. You don’t even usually NEED to use metasploit to scan it, you can just attempt to FTP in and if user: anonymous and password: anonymous doesn’t work, then it’s not anonymous login haha. Let’s go ahead and login to the FTP server.

Annnnd, success! Just like I thought. Time to poke around a bit.

So there are two files in here, locks.txt and task.txt. Let’s download and open them up.

Cool, so this looks like a password list. It’ll come in handy later, so store it somewhere safe. No, there’s one bit I missed documenting here, but I’ll do my best to explain it.

On our scan, port 80 was open, which is http. This means they are most likely running a website. Which also means there could be extra directories, code to audit, etc. Through exploring that site, I found the name “lin”. This appeared to be a username of some sorts. So we had a username, and now we have a list of passwords. There’s one service that has yet to be useful to us; SSH. So, it’s gotta be the login to that. Power up Hydra and let’s get to brute forcing.

Start her up!

Nice! Glad to know that worked out in our favor. Let’s see what we can get to through SSH.

So our goals for this challenge were to get user.txt and root.txt. We’ve got user.txt, so now we need to get root on the box, and that means a little bit of privilege escalation.

This shows that the user we are logged in as (lin) can run the following commands as root: /bin/tar. This means we need to head over our favorite site (https://gtfobins.github.io/) to see how we can escape to root using this command.

Looks like it worked, and the box is now fully completed!

Thanks for reading!

Analysis of Commands Used in TryHackMe’s “Kenobi” box

This is more just notes for me than anything, but here we go:

So this is an nmap scan being used to enumerate for SMB shares. Let’s dissect it.

  • “-p 445” means it is only scanning the specified port, AKA port 445
  • “–script=” there are a bunch of different scripts, directories, script-categories, and more in here
  • “smb-enum-shares.nse” and “smb-enum-users.nse” are scripts developed for nmap to do what their names describe; they enumerate smb shares and users of the smb shares. More info on at least one of these scripts can be found here.

The rest of this (nmap, machine_ip) is pretty self-explanatory.

Here are some of the SMB commands. Luckily, “smbclient” is a pretty simple one. It is similar to how an ftp connection works through the command line, and just connects to an SMB instance on a certain machine’s IP.

“smbget -r” downloads files from a share. The “r” is for resume, which means it automatically resumes aborted files.

So, here’s another nmap scan:

  • “nfs-ls,nfs-statfs,nfs-showmount” these can be looked at online @ nmap’s official site, the main one we are concerned with is here.

This shows NFS exports, and is what we are mainly after. The others gather the extra info that we rely on as well, but this question on the box’s page surrounds the mount that we can see.

The next question I need to answer for myself is: what is netcat?

Well, netcat is a utility that lets you read and write from connections using TCP or UDP. It has been described as a “networking swiss army knife” and can do a ton of different things. It would definitely be out of my depth to currently attempt to put into words all the things it can do, but it does look very useful.

Searchsploit is a command line search tool that checks Exploit-Db. This is useful because it lets you take an offline version of their database with you wherever you go, and is easily accessed from the command line. It can show exploits and shellcode useful for all manner of things.

Here “proftpd” is the service we are looking for exploits for, and “version” is where we will put the version number, like “1.3.5”.

Now we’ll take a look at two more commands. “SITE CPFR” specifies the file you want to copy, while “SITE CPTO” specifies where you want to copy it to.

“Mkdir” creates a directory. “mount” mounts a drive/directory. This can be used to mount an smb share. “mount machine_ip:/var /mnt/kenobiNFS” mounts this machines /var to our newly created directory. “ls -la” then displays the contents of a directory with a lot of extra info for each file, like the size in bytes, last time of modification, etc. The “a” of “la” lists all entries in the directory, including the entries that begin with a period.

  • “find” takes a path to find things, searches for the parameters you feed it.
  • “/” means find will look through every file on the system.
  • “-perm” means you are looking for a file based on permissions. Which is where this next bit comes in.
  • “-u=s” u stands for user, and the s means “set user or group ID on execution”.
  • “-type f” means that it will only look for files. So type is specifying what type of things it is looking for, and f is specifying files.
  • “2>/dev/null” is apparently a fancy way of redirecting stderr to a black hole. This means it discards the output of the command.

Now, I’m going to attempt to walk myself through this. It might be right, it might be wrong.

So since we cannot run usr/bin/sh the way we want to, we copied its contents, and created a new file named curl with the same content. Now, just running curl wouldn’t work because we still need the correct permissions inside and out. We moved it into the way of /usr/bin/menu, a file that we CAN run, and so that when menu gets run, it hits our curl, which in turn gives us the access we need. This is because it has now fully run our shell (curl) as root.

Hopefully that was a semi-correct explanation. Cool stuff though, I’m looking forwards to doing more of these!

TryHackMe | OhSINT

Another box down on TryHackMe! Now admittedly, this is a much more beginner-oriented box, but it is a great introduction to OSINT (Open-Source Intelligence). There were some cool challenges, but some of it I find out a little funky/cheesy (like the final question). But overall, it was a fun experience.

It starts off by giving us an image to download. So, unless the message is directly hidden in the picture itself, the next step would be to take a look at the EXIF/XMP info that is stored on this image. This can include info like the type of camera used to take the photo, the geo-location, the name of the author, and much more!

So what you end up needing to do, is you can either use your computer to use this data, or some type of tool that can display this EXIF/XMP data for us.

In the copyright for the photo, we can see the name “OWoodflint”. Since there isn’t much else popping out right now, let’s just plug it into Google.

And the top three results are exactly what we are looking for! I just pulled them all up right away to take a quick scan over them.

On his Twitter page we can see that the profile picture is of a cat, so that answers our first question. The next question is to see what city they live in.

Scrolling through the Twitter page, there is a BSSID for a network there. Since he mentions that his house is near this network and that he can access it, if we can find where this network is, we can find his rough location.

Online there are lots of different ways and tools to do this, but I chose Wiggle to check and see if it was recorded in their database. Wiggle is a war-driving program. When people are on the go, they can turn on Wiggle, and it will scan all of the WiFi networks around them, and upload the data that they grab to this service. By inputting his BSSID, I was able to track down the city that he was located in, along with the info for the next question, which was regarding what the SSID of the WAP he was connected to is.

Our next quest is to find his email address. We’ve bled his twitter page pretty dry, so let’s take a look at his GitHub page.

There you have it! Easy enough to find. This info answers the next question as well. Now we are going to attempt to find out where he went on Holiday. Since there is no other info on the GitHub page, we are going to go to the last resource we have; his WordPress site.

Aaaaaaaand it says it right there on the front page, easy-peasy. The final question was a little rougher, because so far in my exploration, I haven’t found this to be a useful thing to do when doing OSINT challenges, but it is included in here. It is to find his password.

This is why I thought it was a bit cheesy. Most of the time, you probably will not run into situations where the user has their password publicly posted, just slightly hidden/white text on a white background. Taking a look at the HTML we see:

That it is just a new paragraph on the post, the text has no color, and is just sitting there. Normally, we might be looking more towards password dumps/breaches to find old passwords for people, but I guess this works too!

Overall, a great beginner box, and a great one to do when you only have a little bit of time and still want some fun.

TryHackMe | Blue

So recently I started to try my hand at vulnerable boxes, and some of my friends recommended a website called “TryHackMe” because it’s a little nicer to beginners than some VulnHub/HackTheBox boxes are, so I decided to go for it! Here is a short overview of my journey exploiting this box.

If you have any questions, feel free to leave a comment. Some of my answers/explanations may not match up to the answers I gave on TryHackMe, and that is just because they expected a very linear approach and I accidentally went off and used an exploit that did basically the same thing, just in a different way.

So our first task is to scan the machine. TryHackMe gives you an IP, so I booted up Kali, started using ZenMap (yeah I know, I’m a pleb), and hit the machine with an intense scan. The only reason I started with the intense scan is because this is just a box challenge, a normal scenario would require a bit more finesse.

And as you can see outlined in red, I was able to find the three ports that are open that were under 1000.

So, since this box is based off of EternalBlue, and there is an nmap scan specifically for these vulnerabilities, I created a new custom ZenMap profile and did a custom scan looking for these vulnerabilities, plus a few other things.

Now, you can see that this box is definitely vulnerable to the vulnerabilities we were looking for.

In this pic, you can see what options are available in Metasploit to use to get into this box. I would recommend attempting this exploit in any other way than using Metasploit (just for the sake of experience), or at the very least, find a small script yourself (like a python one), study the script a bit, and then use it to exploit the box. The only reason I didn’t, was because I was racing a friend on this box.

Also, you’ll see that I set all of the options for Metasploit to exploit the box successfully.

Hitting “run”, and we’ve got a successful session on the machine, we will want to background this session, just to check a couple other things out real quick.

Running ifconfig, it comes back successfully identifying that we are on the machine now.

getsystem also identifies that we have Admin as well.

Starting a shell, and running whoami, shows that kind of system we are on, and what authority we have.

And we migrated our session to a different service ID on the system successfully. During this though, our process may or may not die, so we might need to restart it!

The three main reasons for migrating the process is:

  1. You have an unstable shell and might need to move to a more “robust” process.
  2. Some exploits require an interactive session (AKA not session 0).
  3. You need to migrate from a 32-bit process to a 64-bit operating system.

You can read more about process migration here.

Using hashdump, we can see that there are three users on the computer. We want into the “Jon” user account though, so we are going to grab that hash and try to crack it.

Luckily, the hash itself is pretty easy to crack using an online database, and we get the password, which is “alqfna22”.

And just as a side note, sites like crackstation don’t usually actively crack hashes for you. They just match the hash up to a preexisting one in their database and give you the result. So it’s a quick and easy way to do it if you don’t feel like actually going through the cracking process, and sometimes you get lucky and find matches.

Now we are on the hunt for flags. Using search search -f flag*.txt we were able to find all of the text files with the word “flag” on the box. The asterisk at the end before “.txt” is a wildcard, which is why flag1, flag2, and flag3 all showed up. All that’s really left is to traverse to those parts of the directory and see what’s inside those files.

This box was a great experience for a beginner like me, and I had a ton of fun working on it! It took me just barely under an hour, and was very short but sweet, and has encouraged me to continue to try out more boxes.

Thanks for giving this a read!