Disclaimer. Okay, we are not actually going to “hack” your bank account. But we are going to quickly use the developer tools to manipulate text on our browser.
Log into your bank account.
Find your bank and the current amount.
Open up the Developer Tools ( Menu Option > More tools > Web Developer Tools
In the top left of the developer window, select the mouse. This should let you go to the web page, click on your “account balance”.
Double click and change your “account balance” to $1 Million.
Congratulations! You are a millionaire. At least on paper.
*If you honestly were looking for a way to hack your bank account for 1 million dollars… Stop…
Ran across an email that had an attachment named Payment.htm. This kind of phishing attack isn’t anything new, but the htm file had some interesting obfuscation inside of it.
Opening up the file in a virtual a Kali virtual machine, starts to load what appears to look like a Microsoft Sharepoint site. Notice the URL is the local file. It’s setup to pull the photos from the web. Since the VM had no internet available, the images never loaded.
After spinning around for a second, it loads the “log on page”, already populated with our email address. Note I changed the email address before taking the screenshot.
Typing in a random password and hitting Sign in triggers the sign in page.
Notice the ipinfo.io network connection
Going to https://ipinfo.io/json gives us a good bit of info about our IP address, location etc. It looks like this information is requested and then sent to the hackers.
Since there was not an internet connection, the malicious htm web page never received the IP information and so didn’t continue on to the next stage, it just sat there loading. Should be able to setup a fake local server and feed it the information to continue on to the next stage. Or we can just do some static code analysis
Base64, Base64 and more Base64
Opening up the file in a text editor shows tons of Base64 encoded data. The file is only about 20 lines long, but the individual lines are super long.
This first section of Base64 encoded data is by far the shortest. atob is a javascript function that decodes Base64 data. There are multiple atob functions, meaning that to actually get the data, we’ll need to decode the data multiple times. Or we can just copy out the atob functions, and run them directly in Node.js to get the output.
This is fairly easy to do, run nodejs from the command line, set the variable, and print it to console
# nodejs
> let b64 = atob(atob(etc...etc...etc...))
> console.log(b64)
Unfortunately, the next few lines are too large to do what we just did. What we can do is duplicate the file, then delete all non javascript text. Next we can replace the beginning lines where it says “document.head……atob” to
console.log(atob(atob(atob(.....))));
After we have cleaned up the file and made those changes, we save it, and now run it as a javascript file.
nodejs ./Payment.htm
If we want to, we can pipe the output into another file with the > operator
nodejs ./Payment.htm > Decoded_Payment.js
Deobfuscating the important stuff
Looking at the decoded code shows that there is still some obfuscated stuff in that last line.
The var _0x8378= array contains a lot of human unreadable text.
Fortunately, this is not hard to decode at all. In a terminal, launch nodejs again, copy the whole array as a variable, and then just print the whole array.
The last URL is the ipinfo.io one we saw in the browser developer tools. Some of the variables from the above variable also seem to map to the return info from ipinfo.
Getting around applications that strip directory traversal sequences
Using a null byte
Directory Traversal
What exactly is directory traversal anyway? Well, it is pretty much exactly what it sounds like. We traverse directories by manipulate the file path, for something like an image, to get something more valuable like the passwd file.
In it’s most basic form, we can add ../../../../../etc/passwd to a file path and instead of pulling an image, we get the passwd file.
For instance, if we load an image on a website, it’s file path on the server may be something like /var/www/html/image.png. If we right click on an image and open in a new tab and inspect the URL, we can see this path. “Note: Web servers have a root directory for all the website files. Generally web files’ root starts there not / root of the machine.”
Now if we remove image.png and replace it with ../ (../ on Linux/macOS or ..\ on Windows) we’ll go backwards one directory. String them together and we can go back to the root of the drive. Then we can add /etc/passwd (Or replace with whatever file we want) and load the contents of that file.
Most web applications should have some sort of protections in place to guard against directory traversal. Let’s go over a few ways to get around it.
URL Encoding
URL encoding sometimes can work and is simple to do. In Burp, select the file path, right click, Convert selection -> URL -> URL-encode all characters.
You can also try double encoding. Encode once, select the encoded text and encode again.
In the above screenshots, ../../etc/passwd becomes “%25%32%65%25%32%65%25%32%66%25%32%65%25%32%65%25%32%66%25%36%35%25%37%34%25%36%33%25%32%66%25%37%30%25%36%31%25%37%33%25%37%33%25%37%37%25%36%34”
Getting around applications that strip directory traversal sequences
Sometimes the web app can strip out text that it knows is directory traversal characters/sequences. For instance, it sees ../ in the requested url and just strips it out.
We can do something like the following sequence to get around it.
....//....//etc/passwd
That is 4 periods, followed by 2 slashes. What happens is the web app reads the URL, goes hey ../ is not allowed, bye bye! Removes the two instances of ../ and forwards the URL on. Which ends up being
../../etc/passwd
Which is just perfect for our use case.
Using a Null Byte
If the application is using the file extension to validate that an image or other file is loaded, instead of say passwd, we can try using a null byte. A null byte is used to terminate a string.
../../etc/passwd%00.png
What can end up happening is the web application sees the .png or .jpg at the end and goes “oh that is a valid extension, carry on” and then the system reads the line and sees the null byte and says “Oh null byte! end of file path, here is your file.”
[VERBOSE] Disabled child 2 because of too many errors [VERBOSE] Disabled child 6 because of too many errors [ERROR] could not connect to target port 22: Socket error: Connection reset by peer [ERROR] could not connect to target port 22: Socket error: Connection reset by peer [ERROR] could not connect to target port 22: Socket error: Connection reset by peer [ERROR] could not connect to target port 22: Socket error: Connection reset by peer [ERROR] ssh protocol error
Looks like the issue can happen if you have too many threads going at once. Lower the amount of threads your using with -t. Recommended amount for ssh is 4.
You can swap out the ?d from the above command with any of the built in character sets below.
? | Charset
===+=========
l | abcdefghijklmnopqrstuvwxyz
u | ABCDEFGHIJKLMNOPQRSTUVWXYZ
d | 0123456789
h | 0123456789abcdef
H | 0123456789ABCDEF
s | !"#$%&'()*+,-./:;<=>?@[\]^_`{|}~
a | ?l?u?d?s
b | 0x00 - 0xff
./hashcat64.bin -t 32 -a 7 example0.hash ?a?a?a?a example.dict
Example script:
sudo dnf install p7zip
wget https://hashcat.net/files/hashcat-4.1.0.7z
7z x hashcat-4.1.0.7z
cd hashcat-4.1.0
./hashcat64.bin -t 32 -a 7 example0.hash ?a?a?a?a example.dict
Errors:
If you get the following error, try re-extracting the 7z file with the “x” option, not “e”. “x : eXtract files with full paths” and ” e : Extract files from archive (without using directory names)”
