‘Ransomware’ Malware Threats Increasing

A particularly nasty type of attack named”ransomware” is on the rise, with antivirus vendor Symantec seeing at least three new variants appearing in recent months. Such attacks often use viruses to not only steal a person’s sensitive or financial information, but also to disable hard drives and demand money to restore them.

“Threats that use extortion can be some of the most aggressive and, in some cases, offensive viruses encountered,” said Symantec security researcher Gavin O Gorman in a blog post.

Unfortunately for computer owners, attackers continue increase the sophistication levels of their ransomware. For example, GPCoder.G, which first appeared in November 2010, is a small (only 11 kilobytes ) piece of malware which, if executed, searches a hard drive for files with specific extensions, relating to everything from videos and Microsoft Office files to images and music. It then encrypts the first half of all files found, using a symmetric RSA encryption algorithm and a random key. The random, private key is then encrypted using a public key. “Without the private key from this key pair, it is not possible to obtain the symmetric key in order to decrypt the files,” said O Gorman.

To get the private key, the ransomware victim must forward the encrypted symmetric key to attackers, who decrypt and return it. Unfortunately, aside from restoring the encrypted files from a backup, “there is no way to bypass this technique,” he said.   Read More….