As security researchers investigate last Friday’s massive attack from the WannaCry ransomware, they’ve noticed clues that may link it with a North Korean hacking group that has been blamed for attacking banks across the world.
The evidence is far from a smoking gun, and may prove inconclusive. But security researchers have noticed a similarity between an earlier version of WannaCry and a hacking tool used by the Lazarus Group.
Both the 2014 Sony Hack and a string of recent banking heists have been tied to the group, which security researchers suspect works for North Korea.
Apparently, a variant of WannaCry found in February shared some computer code with a hacking tool the Lazarus group used in 2015.
Google researcher Neel Mehta noticed the similarity on Monday, which was confirmed by other experts including those at security firm Kaspersky Lab.
“For now, more research is required into older versions of Wannacry,” Kaspersky Lab said in a blog post. “We believe this might hold the key to solve some of the mysteries around this attack.”
On Monday, security firm Symantec also reported finding clues that may link WannaCry with the shadowy group. It’s found earlier versions of the ransomware on machines that have been compromised by hacking tools used by Lazarus, according to Vikram Thakur, technical director at the company.
“Shortly after these tools were found on these machines, we could see WannaCry files showing up,” he said.
However, all of these WannaCry samples are earlier variants and different from the one that struck on Friday and infected Windows systems across the world.
Symantec is investigating whether the newer WannaCry samples also share any code overlap with the Lazarus Group’s hacking tools, Thakur said.
But even if they do, it’s still possible a separate hacker may have stolen snippets of code from past malware associated with the shadowy group.
Once hacking tools are used, they often leak on the internet, meaning anyone can use them, according to security experts. Thakur said Symantec is investigating how prevalent this shared code is.
If it’s in wide-use, then the likelihood Lazarus was involved with WannaCry will shrink, he said.
The machines Symantec found infected with both the Lazarus tools and WannaCry may have also been infected with other forms of malware, Thakur said. If so, that would suggest different hackers had targeted the same system, making the evidence more circumstantial.
“I think it’s a little early in our analysis to conclude anything,” he said.
Nevertheless, governments across the world are investigating who was behind Friday’s ransomware attack.
“Attribution can be difficult here,” said U.S. homeland security advisor Tom Bossert in a Monday press briefing. “I don’t want to say we have no clues… the best and brightest are working on that.”