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Your files got encrypted by a RANSOMWARE!

On March 14, 2014 I got infected by a ransomware, a malicious program that encrypts your files upon infection and demands a payment in order to recover your files. This particular malware called CryptoDefense creates the following files after it has encrypted all your videos, music and documents: "HOW_DECRYPT.TXT", "HOW_DECRYPT.HTML" and "HOW_DECRYPT.URL" hence the name of this blog. 


Screenshot of files on Windows 7


The text in these files reads:


All files including videos, photos and documents on your computer are encrypted by CryptoDefense Software.
Encryption was produced using a unique public key RSA-2048 generated for this computer. To decrypt files you need to obtain the private key. 
The single copy of the private key, which will allow you to decrypt the files, located on a secret server on the Internet; the server will destroy the key after a month. After that, nobody and never will be able to restore files.
In order to decrypt the files, open your personal page on the site https://*************.onion.to/**** and follow the instructions.
If https://***********.onion.to/**** is not opening, please follow the steps below: 
1. You must download and install this browser http://www.torproject.org/projects/torbrowser.html.en
  
2. After installation, run the browser and enter the address: ***************.onion/***. Follow the instructions on the web-site. We remind you that the sooner you do, the more chances are left to recover the files. 
IMPORTANT INFORMATION:
Your Personal PAGE: https://************m.onion.to/***Your Personal PAGE(using TorBrowser): ***********.onion/***Your Personal CODE(if you open site directly): ****

Damn!

As you probably figured out, if you have seen this on your computer, you are screwed up unless you are willing to pay the ransom they ask for (around $300 dollars) in order to receive the program that restores your files their so-called Decryption Service.
But guess what, based on many victim's reports, not all of them were lucky enough to receive it after payment. So, it's up to you to pay for your beloved data or not (personally, I wouldn't. SCREW THEM!).

Can I somehow crack/get the decryption private key without paying?

No, the computational power required to crack/brute-force a 2048 bit key in less than thousands of years is currently unavailable (and unimaginable) at least for today's technological standards. Even for those super-computers used in biomolecular research and weather forecast. However, I've found vulnerabilities in the Malware itself, not in its RSA2048 algorithm, rather in its faulty implementation. 

Just to give you an idea: Julian Assange (Wikileaks founder and author) encrypted a 21% of that mega-archi-controversial Wikileaks file with a comparatively small AES 256 bits key as an insurance. Insurance? you may wonder. Yes! If something bad were about to happen to him, a handful of his friends who possess the key would publish it and then all those who downloaded the Wikileaks file would finally be able to read beyond the 79% of it. Crazy uh? And it's just 256 bits...

In short: Without the key, you cannot restore your files in this life. Period. 

What about you? What can you do?

First and foremost, update your antivirus and scan your entire system in the search of this malware. If you have no anti-virus or if nothing was found, then download this removal tool from Bit-Defender HERE. At least it will prevent future attacks by this malware.

Hold on a second: Good news!

Use the Cloud! (Dropbox for example)

Upload your pictures, videos and music to a safe storage on the net. These services are run and managed by professionals 24/7. 

Burn DVDs and Bluerays

Regularly back-up your files on these disks. Once they safely land on their surface, no virus in the world can damage them. 

Comments

  1. I was infected on my work computer, I assure you I was not on an adult site either. My dropbox files were also corrupted, not all of them but most of them, my laptop hard drive, my personal network drive, the share network drive has files that were corrupted. I am frustrated because we (county wide tech support) can't figure out were it came from.

    ReplyDelete
  2. They seem to originate from Russia. Are you sure you have exactly what this post describes? If not, there may be other ways out.

    ReplyDelete

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Wana Decryptor / WanaCrypt0r

Alright, guys. This is a tough one: However, there's no reason to claim it's impossible to decrypt victims data. These idiots always let something slip through their fingers. Their servers might be found and keys restored to their respective victims. Errors might be found in their code, their key encryption scheme may have some weakness, etc. Let's just let the experts find a way out.

By the way, if you want to temporarily protect your PC from this malware, you may do this.


Working backwards to the seeds! (OUTDATED)

Note: 
This article is technically accurate and it can be applied to rudimentary RSA implementations that only use time retrieval functions as seed as demonstrated by CS Students from Virginia University
However, CryptoDefense uses CrytoAPI which uses a robust PRNG based on process ID, thread ID,  system clock, system time, system counter, memory status, free disk clusters, etc. I dramatically changed the keys recovery approach as soon as I found out the keys were stored on disk. Why keep this article then? Oh, we wanted the crooks to think we were down the wrong path ;)

Do NOT use somebody else's decryption program!
The reason why each key is unique and why you can't use somebody else's decryption program is because this ransomware randomly generates the keys for each victim. If there was a unique private key for everyone, there would be no need to panic!

But the is a problem...

Software alone is technically incapable of generating random numbers in its truest sense. This exp…

CryptoDefense: Keys pair stored on disk!

This little detail slipped through their fingers... TOO LATE!

(I actually hid this post when I understood that it might alert the crooks. But SYMANTEC did!)

This is the exact path where your keys are:


Windows XP
C:\Documents and Settings\<USERNAME>\Application Data\Microsoft\Crypto\RSA\S-1-5-2... Windows 7
X:\Users\<USERNAME>\AppData\Roaming\Microsoft\Crypto\RSA\S-1-5-21... (X stands for your hard-disk letter, which is commonly C in most computers)

The private key is encrypted via DPAPI (Data Protection API). There are many RSA keys in that folder though, but you can still find them by sorting these files by date. If you don't remember the date you got infected, see your screenshot at the crook's webpage or search for the oldest HOW_DECRYPT.TXT file in your system.
I'll update this blog soon!