Shark, a newly observed type of ransomware, is available for free on underground forums, but its authors demand a 20% cut of the profits, security researchers say.
The creators of Shark have adopted the highly popular ransomware-as-a-service business model and are distributing their creation through a professional looking website that provides aspiring attackers with details on how to download and configure Shark. The author also touts the malware as being fully customizable, and reveals that it uses a fast encryption algorithm, supports multiple languages, and is “undetectable” by antivirus software.
Symantec’s security researchers reveal that interested actors can choose what folders and file formats the ransomware would target and can also set the ransom amount the victim has to pay. Furthermore, the attacker can enter an email address to be informed when the customized payload they created has infected a system.
The payment is also touted as being fully automated, and the ransomware author says they will take a 20% cut from all paid ransoms. In fact, because of a centralized payment system, all ransom payments are made directly to the developers, who then pass the 80% cut to the attacker.
What’s interesting about the Shark ransomware is that it is hosted on a publicly accessible WordPress site, and not on a Tor address. The project was launched sometime in July, and allows all interested attackers to download the malware in a zip file called PayloadBundle.zip. This file includes the ransomware configuration builder (Payload Builder.exe), a warning note (Readme.txt), and the ransomware executable (Shark.exe), Bleeping Computer explains.
The warning note informs them that they should work with all files in a virtual machine and that they should not run “payload.exe.” The executable this warning note refers to, of course, is none other than Shark.exe.
Wannabe attackers only need to run the configuration builder to start tailoring the ransomware to their needs. As soon as the configuration is entered, a base64 version of the configuration is generated and the code is used as an argument to Shark.exe.
According to researchers, the ransomware appends the .locked extension to encrypted files and stores the name of all encrypted files in the %UserProfile%AppDataRoamingSettingsfiles.ini file. Moreover, the ransomware extracts a randomly named executable titled “decrypter” into the %UserProfile%AppDataRoamingSettings folder.
After completing the encryption process, the decrypter would inform users on how they can pay the ransom, and allows victims to view these instruction in 30 different languages. The victim needs to enter an email address and then pay the ransom to a specific Bitcoin address. Victims would supposedly receive a password to decrypt their files after the payment has been made.
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