RYUK Ransomware is virulent ransomware threat, based on the code of Hermes 2.1 and BitPaymer viruses. Researchers believe, that famous Lazarus Group is responsible for the development and implementation of the virus. Latest variations of this virus append .RYK or .rcrypted extension to encrypted files. Hackers demand 15-50 BTC for decryption, which is great amount. RYUK Ransomware does not bypass UAC, requires permission to run, which means user granted access to the computer for virus executable file. Ransomware encrypts all files except ones in following folders: “Windows”, “Mozilla”, “Chrome”, “RecycleBin”, “Ahnlab”. Before the onset of destructive activity, malware stops more than 180 services and 40 processes, by using taskkill and net stop commands. Stopped services and processes mainly belong to antivirus software, running databases, software for backup and editing documents that can prevent file encryption.
This is fourth iteration of notorious STOP Ransomware, that was launched in November, 2018. Now it adds .DATAWAIT, .INFOWAIT or .shadow extensions to encrypted files. Virus uses new name for ransom note: !readme.txt. It pretends to be a Windows update and uses the TeamViewer resource. Ransomware still uses RSA-1024 encryption algorithm. Current version of STOP Ransomware was developed in Visual Studio 2017. This variation of STOP Ransomware demands $290 ransom for decryption. Malefactors offer 50% discount, if users pay in 72 hours. At the moment, there are no decryption tools availabe for STOP Ransomware.
Puma Ransomware, that started to hit thousands of computers in November, 2018, is, actually, nothing but another variation of STOP Ransomware. Current version appends .puma, .pumax or .pumas extensions to encrypted files, and that is why it has such nickname. Virus uses the same name for ransom note file: !readme.txt. Developers tried to confuse ransomware identification services and users by adding new extensions, but using the same templates, code and other signs unequivocally indicate belonging to a certain family. As we see from the name of the executable: updatewin.exe, it pretends to be a Windows update. Puma (STOP) Ransomware still uses RSA-1024 encryption algorithm. Current version of Puma Ransomware was developed in Visual Studio 2017.
Everbe 2.0 Ransomware is second generation of wide-spread Everbe Ransomware. It is file-encryption virus, that encrypts user files using combination of AES (or DES) and RSA-2048 encryption algorithms and then extorts certain amount in BitCoins for decryption. The initial virus first appeared in March, 2018 and was very active since that time. Security researchers consider, that Everbe 2.0 Ransomware started its distribution on 4th of July 2018. Everbe 2.0 Ransomware authors demand from $300 to $1500 in BTC (BitCoins) for decryption, but offer to decrypt any 3 files for free. It is worth mentioning, that Everbe 2.0 Ransomware works only on Windows 64-bit versions of OS. Currently, there is no decryption tools available for Everbe 2.0 Ransomware, however, we recommend you to try using instructions and tools below.
GandCrab V4 Ransomware fourth generation of notorious GandCrab Ransomware. Virus uses complex combination of AES-256 (CBC-mode), RSA-2048 and Salsa20 encryption algorithms. This particular version adds .KRAB extension to encrypted files and creates slightly different ransom note called KRAB-DECRYPT.txt. GandCrab V4 Ransomware demands ransom in BitCoins. Usually, it varies from $200 to $1000. Malware encrypts all types of files except ones in the whitelist and some necessary for Windows operation. All photos, documents, videos, databases get exncrypted after indection. Virus uses WMIC.exe shadowcopy delete command to remove shadow copies and reduce the chances of recovery. Unfortunately, at the moment we write this article, current decryption tools cannot decrypt GandCrab V4 Ransomware, but we will still provide links to this utilities as they can be updated any day.