Today, on Christmas Eve, G Data malware analyst Karsten Hahn has come across a new ransomware family named DeriaLock, which locks your screen and requests a payment of $30.

Ransomware families generally fall in one of two categories: screen lockers (which prevent access to your computer but leave your files alone) and crypto lockers (which allow you to use your computer but encrypt all your files).

DeriaLock is from the first category, of ransomware families that lock your screen and prevent users from accessing their files or applications but leaving the data intact.

Discovered today after an anonymous user has uploaded a copy of the ransomware's binary on VirusTotal, there's no information on how the ransomware currently spreads.

Once launched into execution, DeriaLock will take the computer's MachineName identifier and generate an MD5 hash. Since malware authors often infect themselves by accident, the DeriaLock source code includes a hard-coded MD5 hash, for which the screen locker won't start. This MD5, seen below, most likely belongs to DeriaLock's author.

Exempted MD5 hash in DeriaLock source code

After checking the MD5 locally, the ransomware then contacts its command and control (C&C) server and retrieves the most current version of itself, saving the file at:

C:\users\appdata\roaming\microsoft\windows\start menu\programs\startup\SystemLock.exe

DeriaLock will then run this file, which now passes all checks and starts the screen-locking behavior by showing a fullscreen window with the following ransom note:

Your System has Locked!
If you try to restart you PC ALL data will delete.
If you want your data back, pay 30 USD.
 
Instuctions:
 
Is give no other way to get you computer/data back exdcept to pay a special Key.
You can buy the Key at the following Skype account: "arizonacode".
If you contact the bellow named Skype account send him you HWID the bottom left is to be seen.
If you Spamming the skype account,  you can't get you data back
After you buy the key, paste him into the textbox.

DeriaLock screen locker

The HWID displayed in the ransom note is the same MD5 hash generated previously.

The screen locker window also includes two buttons that when clicked, provide translations of the ransom note in German and Spanish. Only the German translation button works.

According to Hahn, there was no trace of any Spanish text inside the ransomware's source code, which is the reason why the Spanish translation doesn't show anything.

Below is an image of what happens when users press the German translation button.

DeriaLock German ransom note translation

Dein System ist verschlüsselt!
Falls du deinen PC neustartest werden ALLE Dateien gelöscht.
Wenn du deine Dateien wieder haben willst, bezahle 30€.
 
Anleitung:
 
Es gibt keinen anderen Weg deinen Computer/Daten wieder zu erlangen außer einen bestimmten Schlüssel zu kaufen.
Den Schlüssel kann du bei folgenden Skypeaccount erwerben: "arizonacode".
Wenn du einen von den oben genannten Skype Accounts kontaktiert hast sende ihm deine HWID die unten Links sichtbar ist.
Falls der Account zugespammt wird, kannst du deine Dateien NICHT zurückerlangen.
Nachdem du den Schlüssel erworben hast, füge ihn in die Textbox ein.

Both the English and German ransom notes are full of spelling errors.

In order to keep users from closing the screen-locking window, DeriaLock will search and kill the following processes:

taskmgr
procexp
procexp64
procexp32
skype
chrome
steam
MicrosoftEdge
regedit
msconfig
utilman
cmd
explorer
certmgr
control
cscript

Additionally, if users press the ALT + F4 keyboard shortcut to close the screen locker, a popup appears that reads: "I think that is a bad decision. Nice try mate =)"

DeriaLock popup

If the victim wants to pay the ransom, he must take the HWID, contact the DeriaLock author via Skype, and send the crook $30 through an unknown payment method.

The DeriaLock operator takes this HWID and places it on his server in the form of a text file named: http://server-address/[full_MD5_hash].txt

The content of this file is the DeriaLock unlock code. When the victim's infected computer will query the C&C server the next time, it will discover this file, determine that the victim has paid, take the code and unlock the user's computer, as shown from the code snippet below.

DeriaLock generating the MD5 hash

At the time of writing, Hahn says that the DeriaLock servers are still up and running, meaning the threat is currently being distributed to unsuspecting victims.

Furthermore, Hahn has also discovered that during its regular C&C server query routine, DeriaLock also checks the server for the presence of a special text file.

DeriaLock unlock all command

Based on the file's name (unlock-everybody.txt), we presume that this is a method of removing the screen locker from all infected computers at once.

Hahn tells Bleeping Computer that this file holds the value "0", which means that if the author updates this file to "1", he'll unlock all victims. Let's hope the DeriaLock author feels generous tomorrow morning on Christmas Day.

The good news is that DeriaLock requires the .NET Framework 4.5 to be installed, which means it won't work on Windows XP machines.

UPDATE 1 [December 26, 2016]: Hahn spotted today versions of DeriaLock that encrypt users' files and add the .deria file extension at the end.

UPDATE 2 [December 26, 2016]: Michael Gillespie told Bleeping Computer that he found a way to recover files encrypted by the recent DeriaLock version that appends the .deria extension at the end of files. Victims should reach out to him via his Bleeping Computer profile or Twitter account.

DeriaLock decryptor

UPDATE 3 [December 27, 2016]: Hahn detected a new DeriaLock version that threatens to delete a users' files if he doesn't pay the ransom and restarts his computer. The DeriaLock decrypter created by Gillespie still works.