Note: This project is purely academic, use at your own risk. I do not encourage in any way the use of this software illegally or to attack targets without their previous authorization

The intent here is to disseminate and teach more about security in the actual world. Remember, security is always a double-edged sword

Ransomware is a type of malware that prevents or limits users from accessing their system, either by locking the system's screen or by locking the users' files unless a ransom is paid. More modern ransomware families, collectively categorized as crypto-ransomware, encrypt certain file types on infected systems and forces users to pay the ransom through certain online payment methods to get a decrypt key.

This project aims to build an almost functional crypto-ransomware for educational purposes, written in Go. Basically, it will encrypt your files in background using AES-256-CTR, a strong encryption algorithm, using RSA-4096 to secure the key exchange with server. Yeah, a Cryptolocker like malware.

It is composed of two main parts, the server and the malware itself.

The server is responsible for store the Id and the respective encryption key and possibly act as a Command and Control server in the near future.

The malware encrypt with your RSA-4096 public key any payload before send then to the server. This approach with the https transport together make the security and authentication almost unbreakable (in theory)

• Run in Background (or not)
• Encrypt files using AES-256-CTR(Counter Mode) with random IV for each file
• Without virus signature (at the moment)
• Use RSA-4096 to secure the authenticity
• HTTPS and HTTP\2 Transport by default
• Stream encryption to avoid load an entire file into memory
• Walk all drives by default, including usb's and network locations
• Lock registry entry with hash digest(maybe SHA-256) to identify an infected victim
• Tor or other approach to hide the connection with the C&C see issue 3
• Docker image for compilation

DON'T RUN ransomware.exe IN YOUR PERSONAL MACHINE, EXECUTE ONLY IN A TEST ENVIRONMENT!

go get -v github.com/mauri870/ransomware
cd $GOPATH/src/github.com/mauri870/ransomware
# You can compile the server for windows using env GOOS=windows make instead of make
sh build-docker.sh make

Done! The binaries live on the bin folder

You need Go at least 1.7 with the $GOPATH/bin in your $PATH

go get -v github.com/mauri870/ransomware
go get -v github.com/akavel/rsrc
cd $GOPATH/src/github.com/mauri870/ransomware

Build the project require a lot of steps, like the RSA key generation, build three binaries, embed manifest files, so, let's leave make do your job

make

If you like build the server for windows from a unix machine, run env GOOS=windows make.

DON'T RUN ransomware.exe IN YOUR PERSONAL MACHINE, EXECUTE ONLY IN A TEST ENVIRONMENT!

The malware will run in background. You can see what is going on by simply remove the -ldflags="-H windowsgui" from the binaries section on Makefile before build

By default, the server will listen on https://localhost:8080. The client will use this host as the default url too.

You can put the server on any domain and start it. Simply overwrite the SERVER_URL constant on client/main.go before build and the malware will try to connect with this url instead

After build, a binary called ransomware.exe, server/server.exe and unlocker.exe will be generated on the bin folder. The execution of ransomware.exe and unlocker.exe (even if it is compiled for linux/darwin) is locked to windows machines only.

Feel free to edit the parameters across the files for testing. Put the binaries on a correct windows test environment and start the server. It will wait for the malware contact and persist the id/encryption keys

When double click on ransomware.exe binary it will run on background, walking interesting directories and encrypting all files that match the interesting file extensions using AES-256-CTR and a random IV, recreating then with encrypted content and a custom extension(.encrypted by default) and create a READ_TO_DECRYPT.html file on desktop

In theory, for decrypt your files you need send an amount of BTC to the attacker's wallet, followed by a contact sending your ID(located on the file created on desktop). If your payment was confirmed, the attacker possibly will return your encryption key and the unlocker.exe and you can use then to recover your files. This exchange can be accomplished in several ways and is not been implemented yet.

Let's suppose you get your encryption key back, you can retrieve it pointing to the following url:

curl -k https://localhost:8080/api/keys/:id

Where :id is your identification stored on the file on desktop. After, run the unlocker.exe by double click and follow the instructions.

And that's it, got your files back 😄

The server has only two endpoints at the moment

POST api/keys/add - Used by the malware to persist new keys. Some verifications are made, like the verification of the RSA autenticity. Returns 204 (empty content) in case of success or a json error.

GET api/keys/:id - Id is a 32 characters parameter, representing an Id already persisted. Returns a json containing the encryption key or a json error

As you can see, building a functional ransomware, with some of the best existing algorithms is not dificult, anyone with programming and security skills can build that.