New ‘HavanaCrypt’ ransomware distributed as fake Google software update

Trend Micro security researchers have identified a new ransomware family that is delivered as a fake Google Software Update application.

Dubbed HavanaCrypt, the ransomware performs several anti-virtualization checks and uses a Microsoft web hosting service IP address for its command and control (C&C) server, allowing it to evade detection.

During their analysis of HavanaCryptTrend Micro also discovered that it uses a namespace method function that queues a method for execution and employs open source password manager modules during encryption.

Compiled in .NET and protected using the open source obfuscator Obfuscar, HavanaCrypt hides its window after execution, then checks the AutoRun registry for a “GoogleUpdate” entry and continues its routine if the registry is not found .

Then it proceeds with its anti-virtualization routine, which consists of four steps: first it checks the services associated with the virtual machines, then the files related to the applications of the virtual machines, then the filenames used for the executables virtual machines, then it checks the MAC address of the machine.

If all 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 of database applications (Microsoft SQL Server and MySQL) and those of Microsoft Office and Steam.

Next, 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, defines them as hidden system files, and drops in the “User Startup” folder a .bat file containing a function that disables the Manager stain.

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 serial number. product.

While encrypting, the malware uses the CryptoRandom feature of KeePass Password Safe to generate encryption keys. The threat appends the “.Havana” extension to 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 network Tor.

The malware also creates a text file which records all directories containing the encrypted files. The file is called foo.txt and the ransomware also encrypts it. No ransom note is dropped.

“This could 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,” says Trend Micro.

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Ionut Argire is an international correspondent for SecurityWeek.

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