Security researchers at Trend Micro have identified a new ransomware family that is being delivered as a fake Google Software Update application.
Dubbed HavanaCrypt, the ransomware performs multiple anti-virtualization checks and uses a Microsoft web hosting service IP address for its command and control (C&C) server, which allows it to evade detection.
During their analysis of HavanaCrypt, Trend Micro also discovered that it uses a namespace method function that queues a method for execution and that it employs the modules of an open-source password manager during encryption.
Compiled in .NET and protected using the Obfuscar open-source obfuscator, HavanaCrypt hides its window after execution, then checks the AutoRun registry for a “GoogleUpdate” entry and continues with its routine if the registry is not found.
Next, it proceeds with its anti-virtualization routine, which consists of four stages: first, it checks for services associated with virtual machines, then for files related to virtual machine applications, then for file names used for VM executables, and then it checks the machine’s MAC address.
Should all the checks pass, the malware downloads a file named “2.txt” from a Microsoft web hosting service IP address, saves it as a .bat file, and executes it. The batch file contains instructions for Windows Defender to ignore detections in the “Windows” and “User” directories.
Next, the ransomware terminates a series of running processes, including those for database applications (Microsoft SQL Server and MySQL) and those of Microsoft Office and Steam.
Then, HavanaCrypt queries all disk drives and deletes all shadow copies, and uses Windows Management Instrumentation (WMI) to identify system restore instances and delete them.
After that, the ransomware drops executable copies of itself in the “ProgramData” and “StartUp” folders, sets them as hidden system files, and drops in the “User Startup” folder a .bat file containing a function that disables the Task Manager.
HavanaCrypt generates a unique identifier (UID) based on system information such as processor cores and ID, processor name, socket, motherboard manufacturer and name, BIOS version, and product number.
During encryption, the malware uses the CryptoRandom function of KeePass Password Safe for generating encryption keys. The threat appends the “.Havana” extension to the encrypted files, and avoids encrypting files with certain extensions or those in specific directories, including that of the Tor browser, suggesting that the malware author might plan communication over the Tor network.
The malware also creates a text file that logs all the directories containing the encrypted files. The file is named foo.txt and the ransomware encrypts it as well. No ransom note is dropped.
“This might be an indication that HavanaCrypt is still in its development phase. Nevertheless, it is important to detect and block it before it evolves further and does even more damage,” Trend Micro explains.
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