Windows XP PCs Infected By WCry Can Be Decrypted Without Paying Ransom

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Story : https://arstechnica.com/security/2017/05/windows-xp-pcs-infected-by-wcry-can-be-

Owners of some Windows XP computers infected by the WCry ransomware may be able to decrypt their data without making the $300 to $600 payment demand, a researcher said Thursday.

Adrien Guinet, a researcher with France-based Quarkslab, has released software that he said allowed him to recover the secret decryption key required to restore an infected XP computer in his lab. The software has not yet been tested to see if it works reliably on a large variety of XP computers, and even when it does work, there are limitations. The recovery technique is also of limited value because Windows XP computers weren't affected by last week's major outbreak of WCry. Still, it may be helpful to XP users hit in other campaigns.

"This software has only been tested and known to work under Windows XP," he wrote in a readme note accompanying his app, which he calls Wannakey. "In order to work, your computer must not have been rebooted after being infected. Please also note that you need some luck for this to work (see below), and so it might not work in every case!"

WCry, which also goes by the name WannaCry, covertly encrypts computer files after infecting a computer and then demands owners pay a $300 to $600 ransom to obtain the decryption key required to restore a computer to normal working condition. The ransomware uses the Microsoft Cryptographic Application Program Interface included with Windows to handle many of the functions, including generating the key for encrypting and decrypting the files. After creating and securing the key, the interface erases the key on most versions of Windows.