"Users Warned of New Aerst, ScareCrow, and Vohuk Ransomware Families"

Security researchers at Fortinet have shared information on three new ransomware families named Aerst, ScareCrow, and Vohuk.  The researchers noted that the new ransomware targets Windows computers encrypts victim files, and demands a ransom payment in exchange for a decryption key.  This new ransomware has been used in an increasing number of attacks.  The researchers stated that Aerst was seen appending to encrypted files the ".aerst" extension and displaying a popup window containing the attacker's email address instead of dropping a typical ransom note.  The researchers noted that the popup window contains a field where the victim can enter a purchase key required to restore the encrypted data.  Aerst deletes Volume Shadow copies to prevent file recovery.  The other ransomware Vohuk does drop a ransom note readme.txt, asking the victim to contact the attackers via email.  Seemingly under continuous development, the malware assigns a unique ID to each victim.  The researchers noted that this ransomware family appends the ".vohuk" extension to the encrypted files, replaces file icons with a red lock icon, and changes the desktop wallpaper with its own.  This ransomware leaves a distinctive mutex, "Global\\VohukMutex," which prevents different instances of Vohuk ransomware from running on the same system.  Vohuk has been used mainly to target users in Germany and India.  The third ransomware, ScareCrow, has a ransom note named "readme.txt," which instructs victims to contact the attacker using one of three Telegram channels.  This ransomware seems to be the most widespread, with files submitted from the United States, Germany, India, Italy, the Philippines, and Russia.  The researchers noted that they have identified some similarities between ScareCrow and Conti, such as the use of the CHACHA algorithm for encryption and the use of the WMI command-line utility to delete Volume Shadow copies, which suggest that ScareCrow's developers might have used Conti source code leaked earlier this year.  The researchers stated that the ransomware's developer has encrypted each command string in the malware, including DLL names, API names, and even command strings, with a different decryption routine.  ScareCrow appends the ".crow" extension to the encrypted files.

SecurityWeek reports: "Users Warned of New Aerst, ScareCrow, and Vohuk Ransomware Families"