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.
Your Personal PAGE: https://************m.onion.to/***Your Personal PAGE(using TorBrowser): ***********.onion/***Your Personal CODE(if you open site directly): ****
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.