A new variant of crypto-ransomware, it seems, is not so much crypto, as it allows its victims to get back their data without paying for it. ransom which requires Scraper ransomware appears to have a flaw that practically means around 70% of its victims can decrypt their files, according to Kaspersky Labs, the Russian security firm that published a decryption method.
Of course, it's much better not to get infected, but those who have not watched can use the utility offered by the company to not pay the 300 dollars claimed by the fraudsters.
The Scraper (or TorLocker) malware first appeared in attacks on Japan last October. The Scraper later appeared in an English version, and encrypts the victim's files requiring a ransom (300 dollars or more, depending on the rogue greed to be paid to BitCoin or Ukash) to decrypt them.
More specifically, the malware encrypts almost all of the user's files, documents, video and audio files, images, databases data, αντίγραφα ασφαλείας, κλειδιά κρυπτογράφησης εικονικών μηχανών, πιστοποιητικά και άλλα αρχεία σε όλους τους σκληρούς δίσκους αλλά και στο δίκτυο. Επίσης, διαγράφει όλα τα σημεία της resetof the system. Scraper only infects computers with Windows.
User files are encrypted using multiple AES-256 one-time keys, an encryption key for each file. Kaspersky Labs says that somewhere this process went wrong, although other experts have their own theories. In any case, mistakes have clearly been made, otherwise decryption would be impractical.
"Although Trojan-Ransom.Win32.Scraper encrypts all files with AES-256 + RSA-2048, 70 percent of cases can be decrypted due to errors in the application of encryption algorithms," Kaspersky researchers Victor Alyushin and Fedor Sinitsyn.
If you are infected with malicious software, use the Kaspersky tool directly ScraperDecryptor.zip to decrypt your files. The company offers instructions on how to do it do from here.
One thing is for sure: Scammers will find some way to fix their code and release the new update. So Kaspersky's tool probably has an expiration date.