Cyber criminals have raked in more than $34,000 in the month since CryptoDefense Trojan, a variant of CryptoLocker, first appeared in February 2014 even though a poor implementation of cryptography has left “hostages” with an escape route, according to Symantec.
Symantec has blocked more than 11,000 unique CryptoDefense infections, which are spammed out via email to Windows computers. The ransomware holds victim files hostage by employing public-key cryptography using strong RSA encryption and prevents restoration until a $500 ransom payment is made in bitcoins through a unique Tor payment web page address. If the payment is not made within four days, the ransom doubles.
However, victims need not cough up a penny. They can circumvent the attack and restore files because poor cryptographic implementation by the malware authors leaves the decryption key they’re holding for ransom on the infected computers.