Cartographer[web] HTB walkthrough

Hello everyone, today we are gonna do the Cartographer web challenge from HTB. This challenge is based on basic fuzzing. So let's jump in!

This is the page which appears on visiting the challenge URL:

As can be seen, there is a login page on it. I tried very common and basic credentials like admin:admin, admin:pass etc but none of them worked.

As brute forcing is considered as a bad approach/technique, I thought to try it in the end when I have no other option left. So I started inspecting the source code of login page to find some juice there.

    <title>Cartographer - Login</title>
    <link rel='stylesheet' href='style.css' type='text/css' />
    <div class="content-container">
        <div class="blur"></div>
    <div class="loginform">
            <img src="logo.png" /><br><br>
            <form method="post">
                <input class="textbox" type="text" name="username" placeholder="Username"><br><br>
                <input class="textbox" type="password" name="password" placeholder="Password"><br><br>
                <input class="loginbutton" type="submit" value="Login">

Unfortunately, there was nothing there.

So my next step was to test for SQL injection vulnerability in those form fields. So I gave a try with basic SQLi payload (' or '1=1' #) in username field and got this weird reply:

"Cartographer Is Still Under Construction!". It was not the message itself that was interesting, but the query in URL where this page was found.

Alright, now we have got an interesting page named panel.php and an interesting variable named info that has currently been set to home.

Since that info variable is loading some page, I tried testing it for Local File Inclusion but no luck. At the end, the only option left was to fuzz the variable.

Here, we have two things to fuzz. First the variable name and second is the value of that variable. I tried fuzzing the variable name but got nothing. So now the only option left was to fuzz different values for the same variable info.

But before fuzzing, I need a property that can differentiate the right result from other results. I opened the Burpsuite and intercepted the request with wrong value of info to see how the "not found/failed" response looks like.
I found that the unimportant response has a content length of 375 characters. This info can be used to filter out required results when using tools like wfuzz.

Once I got the property(Content length) which differentiates right results from wrong results, now the next thing to look for is a good wordlist to fuzz the parameter value with.

I searched for parameter fuzzing wordlists in google and came across this wordlist from SecList: . This list contains words that are generally found as parameter names or parameter values in web applications.

Now we have got everything we need, it's time to fuzz the parameter value using wfuzz tool. The command I used was:

wfuzz -z file,params.txt -b "PHPSESSID=r2dut711gvbjmp0kn7v9ca8hf5" --hh 375 -t 60 ""

Command explaination:

The above command produces the following output:

As you can see, other than the known value home, flag was the only value found for the variable info. Let's use this and see what's in there.

So, I requested this URL through browser:

It immediately showed me this output which was nothing but the challenge completion flag. Yay!

I have hidden the flag for security reasons and also so that you can try this challenge out yourself!

Happy Hacking! :-)