New ransomware CryCryptor has been targeting Android users in Canada, distributed via two websites under the guise of an official COVID-19 tracing app. Researchers analyzed the ransomware and created a decryption tool for the victims. Once the user falls victim to CryCryptor, the ransomware encrypts the files on the device – all the most common types of files – but instead of locking the device, it leaves a “readme” file with the attacker’s email in every directory with encrypted files. After launch, the ransomware requests to access files on the device. After obtaining that permission, it encrypts files on external media with certain extensions.
Selected files are encrypted using AES with a randomly generated 16-character key. After CryCryptor encrypts a file, three new files are created, and the original file is removed. The encrypted file has the file extension “.enc” appended, and the algorithm generates a salt unique for every encrypted file, stored with the extension “.enc.salt”; and an initialization vector, “.enc.iv”.