Hacking an encrypted pdf file. Hacking encrypted rar, zip, and 7z archives. Utilities pdf crack, rar crack and more

Tr0jan_Horse

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In today's article, I will share examples of cracking password-encrypted pdf files and archive files. I will show examples of working with such programs as pdf crack, rar crack, John the Ripper. Naturally, these programs work on Linux (in my case Kali Linux), but under Windows I think there are analogues of these programs. And yes, in this article I will touch on examples related to john, although there may be articles related to this program on Habré (and in the Russian-speaking segment of the Internet there are definitely descriptions of how to work with it), but in this article my examples will be relevant and necessary. This is a kind of online cheat sheet on using these utilities.

I carried out all the attacks on my personal computer, where I created my own files, which I attacked, that is, all actions are legitimate.
And as always, please do not get personal in the comments, if you find a mistake, flaw or inaccuracy, just write a comment without insults or write me a personal message.
So let's get down to practice
First, we will find and install these programs in the repository

Bash:
apt search pdfcrack
sudo apt update
sudo apt install pdfcrack

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It's the same with rar crack
Bash:
sudo apt install aircrack
(sudo apt update is no longer required to be entered since it performed this operation)

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Next, I created my pdf from the wikipedia page (Ctrl + P in the browser) and went to the website https://www.ilovepdf.com/ru/protect-pdf where you can encrypt a pdf with a password.

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After the operations, it is possible to download an encrypted pdf
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Even after we fix the pdf crack issue. Open the terminal (of course) and type in the following (general syntax example):

pdfcrack --dictionary=/path/to the dictionary file/dictionary file /path_encrypt_pdf/encrypted_pdf

Or in my case

pdfcrack --wordlist=/usr/share/wordlists/rockyou.txt 1_protected.pdf

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As you can see from the screenshot, the program has selected a dictionary password - freedom4me. Next, all that's left is to enter the password
We find the file, try to open it - it requires a password, enter the selected password:
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As you can see, the file has opened

From the first file (which was not encrypted - 1.pdf), I created a rar archive, naturally password-protected.

Let's try to find a password for it.

For the rar crack program, the syntax (in my case) looked like this:

rarcrack 1.pdf.rar

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As you can see from the screenshot, the program has selected the password - 56 (although it is elementary).

Next, we go to the archive, see that the contents are encrypted (lock on the file), try to open the file - password requirement, enter the password and get the result:

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We try a three-digit password. I have created an encrypted 2.rar archive with a three-digit password.

The algorithm of operations is the same

rar crack 2.rar

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We enter the selected password again (in this case 098)

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I want to say the following about the aircrack program. This program does not have the ability to search through a dictionary. She tries to sort through all possible combinations, starting with two-digit passwords. Therefore, if the password is complex enough, you need to be patient, have time, and have the computing power of the hardware. And in the help (rar crack --help) it is indicated that the program can select passwords not only for rar archives, but also for zip and 7z. But no matter how much I tried to sort through the passwords for zip and 7z, the program could not find passwords for them (although I encrypted them with two-digit passwords).

However, it is possible to use John the Ripper to select a password for zip and 7z. This utility is pre-installed in Kali Linux OS. Instructions for installing it for other distributions will not be difficult to find.

To begin with, I created two archives - 3.zip and 4.7z, naturally password-protected
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Further, the algorithm is as follows
  • Using the utility, we create a hash of the archive file
  • We use the utility to sort passwords using a hash

So, the syntax in my case is this (I open the terminal in the same folder where the archives are located):
Bash:
zip 2 john 3.zip > hash.txt

And here I decided to "look" at the cache and saw "gibberish" (the hash should look like this)

Bash:
cat hash.txt

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After that, we go through the password using the hash. In my case, the syntax looked like this (with a search through the already familiar dictionary):

Bash:
john --wordlist=/usr/share/wordlists/rockyou.txt --format=zip hash.txt

And the password was successfully selected.

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We are doing the same with the second archive.
Bash:
7z2john 3.zip > 7z.hash
John --wordlist=/usr/share/wordlists/rockyou.txt --format=7z 7z.hash

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The password was successfully selected
Now all that remains is to try to unzip the files, of course you will be asked for a password, which we will enter.

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Successfully

And that's all for me today, dear readers, see you soon! And congratulations on the upcoming holidays!
 
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