Ransomware Authors Break New Ground With Petya

Ransomware developers appear to have come up with a new way of making life miserable for victims of their extortion campaigns, even as federal officials in the US and Canada Thursday issued an alert on the scourge.

Security vendor F-Secure on Friday issued an alert on Petya, a new ransomware sample that locks the entire hard disk of a computer instead of simply encrypting files on disk like other ransomware tools.

According to F-Secure, Petya encrypts the filesystem’s master file table (MFT) ensuring that the operating system is unable to locate needed files, thereby rendering the computer completely unusable.

“It installs itself to the disk’s master boot record (MBR) like a bootkit. But instead of covert actions, it displays a red screen with instructions on how to restore the system,” F-Secure senior security researcher Jarkko Turkulainen wrote.

Attacking the MFT takes less time than encrypting files on disk while yielding the same results, F-Secure security advisor Sean Sullivan added in comments to Dark Reading.

“Many of the other crypto-ransomware families require time and CPU,” Sullivan says. Victims of ransomware attacks, in fact, often report their computers slowing down significantly during an attack. While home users may not know quite what to make of the slowdown, employees at enterprises sometime have time to get help in preventing a full compromise, Sullivan says.

With Petya that is not an option. “Petya is able to hit the MFT in seconds before crashing the system and forcing a restart. In an enterprise environment, there would be no time to call for help.”

For victims, Petya introduces problems that other ransomware tools typically do not. Because Petya infects the master boot record, it disables the entire system. So the victim would need to find another computer with Internet access in order to pay off the ransom and regain access to their compromised system. While this may not, by itself, present a problem for business users, home users could find it challenging, Sullivan said.

Petya also leaves it pretty much up to the user to download the Tor browser to access the hidden service URL for paying the ransom.  “Petya doesn’t attempt to provide proxy links to the Tor hidden service,” suggesting that the malware authors either, do not care about the difficulties of installing the Tor browser, or they haven’t incorporated that feature yet, he said.

Somewhat ironically, in making it harder for victims to pay a ransom, Petya’s authors may have also lowered their own chances of profiting from it, says Sullivan. As a result, the likelihood of the same technique being used more widely will depend on the success malware authors have in monetizing Petya.

“That will depend on whether or not people figure out how to pay,” Sullivan says. “It does definitely have some advantages in how it hits its victims. So, we’ll likely see more, but it is too soon to say if it will become common.”

News of Petya comes amid heightening concerns about a major increase in ransomware samples and in ransomware attacks in recent months. Many believe that the success that malware authors have had in extorting money from victims is attracting more criminals, including organized cybercrime groups into the ransomware space. In recent months, ransomware samples like Locky, TeslaCrypt and Samas, have victimized numerous individuals and organizations, including several major hospitals.

The surge in attacks prompted the U.S Department of Homeland Security to issue an alert in conjunction with the Canadian Cyber Incident Response Centre, warning consumers and businesses of the seriousness of the threat. The alert, issued late Thursday, warned consumers and businesses about the “devastating” consequences of a ransomware attack. “Recovery can be a difficult process that may require the services of a reputable data recovery specialist,” the alert noted in offering some precautions.

The recommendations include the need for individuals and organizations to employ a data backup and recovery plan for crucial information and the use of whitelisting to ensure that only approved applications are allowed to run on a system. Other advice included the need for people to jeep their software properly updated and patched and to limit the ability for users to install and run applications on their systems

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