Google vulnerability researcher discovers bug within SymCrypt

Tavis Ormandy, one of Google’s “Project Zero” team’s security researchers discovered a vulnerability that could effectively perform a denial-of-service attack on Windows servers. There is a 90-day disclosure deadline associated with Project Zero, and since it was day 91, Ormandy released the information.

• By Kaitlyn DeHaven
• Jun 14, 2019

A vulnerability researcher who is part of Google’s “Project Zero” team discovered a bug within SymCrypt, the core cryptographic library responsible for implementing asymmetric crypto algorithms in Windows 10 and symmetric crypto algorithms in Windows 8. Davey Winder, a contributor for the Forbes cybersecurity section, said that when the researcher used a malformed digital certificate, he could force the SymCrypt calculations into an infinite loop. This would effectively perform a denial-of-service (DoS) attack on Windows servers such as those running the IPsec protocols that are required when using a VPN or the Microsoft Exchange Server for email and calendaring for example.

The Project Zero deadline to fix issues is 90 days, and because Tuesday, June 11 was day 91, researcher Tavis Ormandy tweeted the issue to make it public. He said that the bug isn’t serious in his opinion, but it’s certainly something to be aware of.

“I consider this relatively low severity, but you could take down an entire Windows fleet relatively easily, so it’s worth being aware of,” Ormandy said in his tweet.

Adam Laub, SVP Product Management at STEALTHbits Technologies said that although this issue is “low severity,” it could be a lot more pungent for organizations that are having a hard time implementing the fix.

“This finding demonstrates just how important this type of research is in helping organizations mitigate risks no one ever knew existed,” Laub said. “The frightening part about this vulnerability and others that can be remedied with a simple patch, however, is that many organizations will have a very difficult time actually implementing the fix.”