WannaCry Hit Windows 7 Machines Most

Don't blame Windows XP: Now that the dust has started to settle in the epic global WannaCry ransomware worm attacks, new data shows that the hardest hit version of Windows in the attacks was the soon-to-be-fully-retired Windows 7 – specifically, the 64-bit version of the OS, which suffered 60% of the ransomware infections, according to data from Kaspersky Lab.

Another 31.72% were Windows 7 proper, and another 6% were Windows 7 Home OS machines.

Amid the chaos and panic during the outbreak and fast spread of the worm that first reared its head on May 12 were calls for organizations to keep their Windows machines updated with the latest patches and to abandon older Windows operating system versions like Windows XP and Windows 7. XP ended up being less of a victim factor than experts initially posited.

Costin Raiu, head of the global research and analysis team at Kaspersky Lab, says the WannaCry attackers didn't activate support for targeting XP machines. "Their code worked only with Windows 7, Windows 7 x64 and Windows 2008 servers," Raiu says. "So, while in theory it was possible to implement support for the infection of Windows XP, it seems they didn't. This could be because they thought almost nobody uses XP anymore, or because they didn't have time to finish the worm before the ransomware was released."

Some XP machines threw error messages or crashed during WannaCry, but they weren't successfully infected with the malware, according to several researchers who studied the code. Microsoft even issued a rare emergency patch for XP and the also-retired Windows 2003 Server platforms out of abundant caution.

While leftover Windows XP-based machines and systems (think some medical and ICS devices) running out there dodged a bullet, the narrative advice of "patch and update" remains just as relevant when it comes to the older and still widely deployed Windows 7 OS, which Microsoft has begun to phase out with some limited extended support options for its business customers. Windows 7 Service Pack 1 expires on January 14, 2020. 

BitSight says the consumer-heavy telecommunications sector led WannaCry infections with 15.31% of the ransomware victims worldwide, and the Russian Federation topped the list of victim nations, with some 25,829 infected machines, followed by China (22,991), Taiwan (7,625), Ukraine (5,974), the US (4,557), and others, in some 167 nations affected by the attack.

Dan Dahlberg, research scientist at BitSight, says researchers are still studying just why Windows 7 was hit hardest. "It is known that the worm had difficulty infecting Windows XP machines and spreading as it often caused the machine to crash when it attempted to exploit the vulnerabilities," he says. "Microsoft has also designed a more seamless automatic update experience for Windows 10 that would have allowed for the MS17-010 patch to be installed on a much larger population of Windows 10 machines compared to older operating systems."

From WannaCry to "EternalRocks"

WannaCry isn't really ever going to be over. Subsequent copycats and variants are circulating at a rapid clip.

The most interesting attack to surface: a piece of malware known as "EternalRocks" network worm that employs six of the NSA tools leaked by Shadow Brokers, which actually dates back to May 3 of this year, before WannaCry was found.

EternalRocks uses multiple SMB exploits from the NSA trove, including EternalBlue (the one WannaCry used), Eternal Champion, EternalRomance, and EternalSynergy, plus the DoublePulsar, Architou8ch, and SMBTouch tools.

Security experts say while the radical combination tool is intriguing, so far it's not doing much damage since it doesn't carry a payload per se: just a backdoor implant. "At this time, the malware is not weaponized, but allows remote code execution once installed on a machine, so it could potentially be weaponized later," notes Chris Hinkley, lead ethical hacker for Armor.

EternalRocks won't be the last of the recycled NSA cyber tools going rogue. Security experts are keeping  close eye on the next wave of attack campaigns now that WannaCry blazed a trail with the worm-spread ransomware technique. 

Related Content: