Microsoft's CEO Satya Nadella has hailed the company's new Recall feature, which stores a history of your computer desktop and makes it available to AI for analysis, as “photographic memory” for your PC. Within the cybersecurity community, meanwhile, the notion of a tool that silently takes a screenshot of your desktop every five seconds has been hailed as a hacker's dream come true and the worst product idea in recent memory.
Now, security researchers have pointed out that even the one remaining security safeguard meant to protect that feature from exploitation can be trivially defeated.
Since Recall was first announced last month, the cybersecurity world has pointed out that if a hacker can install malicious software to gain a foothold on a target machine with the feature enabled, they can quickly gain access to the user's entire history stored by the function. The only barrier, it seemed, to that high-resolution view of a victim's entire life at the keyboard was that accessing Recall's data required administrator privileges on a user's machine. That meant malware without that higher-level privilege would trigger a permission pop-up, allowing users to prevent access, and that malware would also likely be blocked by default from accessing the data on most corporate machines.
Then on Wednesday, James Forshaw, a researcher with Google's Project Zero vulnerability research team, published an update to a blog post pointing out that he had found methods for accessing Recall data without administrator privileges—essentially stripping away even that last fig leaf of protection. “No admin required ;-)” the post concluded.
“Damn,” Forshaw added on Mastodon. “I really thought the Recall database security would at least be, you know, secure.”
Forshaw's blog post described two different techniques to bypass the administrator privilege requirement, both of which exploit ways of defeating a basic security function in Windows known as access control lists that determine which elements on a computer require which privileges to read and alter. One of Forshaw's methods exploits an exception to those control lists, temporarily impersonating a program on Windows machines called AIXHost.exe that can access even restricted databases. Another is even simpler: Forshaw points out that because the Recall data stored on a machine is considered to belong to the user, a hacker with the same privileges as the user could simply rewrite the access control lists on a target machine to grant themselves access to the full database.
That second, simpler bypass technique “is just mindblowing, to be honest,” says Alex Hagenah, a cybersecurity strategist and ethical hacker. Hagenah recently built a proof-of-concept hacker tool called TotalRecall designed to show that someone who gained access to a victim's machine with Recall could immediately siphon out all the user's history recorded by the feature. Hagenah's tool, however, still required that hackers find another way to gain administrator privileges through a so-called “privilege escalation” technique before his tool would work.
With Forshaw's technique, “you don’t need any privilege escalation, no pop-up, nothing,” says Hagenah. “This would make sense to implement in the tool for a bad guy.”
In fact, just an hour after speaking to WIRED about Forshaw's finding, Hagenah added the simpler of Forshaw's two techniques to his TotalRecall tool, then confirmed that the trick worked by accessing all the Recall history data stored on another user's machine for which he didn't have administrator access. “So simple and genius,” he wrote in a text to WIRED after testing the technique.
That confirmation removes one of the last arguments Recall's defenders have had against criticisms that the feature acts as, essentially, a piece of pre-installed spyware on a user's machine, ready to be exploited by any hacker who can gain a foothold on the device. “It makes your security very fragile, in the sense that anyone who penetrates your computer for even a second can get your whole history,” says Dave Aitel, the founder of the cybersecurity firm Immunity and a former NSA hacker. “Which is not something people want.”
For now, security researchers have been testing Recall in preview versions of the tool ahead of its expected launch later this month. Microsoft said it plans to integrate Recall on compatible Copilot+ PCs with the feature turned on by default. WIRED reached out to the company for comment on Forshaw's findings about Recall's security issues, but the company has yet to respond.
The revelation that hackers can exploit Recall without even using a separate privilege escalation technique only contributes further to the sense that the feature was rushed to market without a proper review from the company's cybersecurity team—despite the company's CEO Nadella proclaiming just last month that Microsoft would make security its first priority in every decision going forward. “You cannot convince me that Microsoft's security teams looked at this and said ‘that looks secure,’” says Jake Williams, a former NSA hacker and now the VP of R&D at the cybersecurity consultancy Hunter Strategy, where he says he's been asked by some of the firm's clients to test Recall's security before they add Microsoft devices that use it to their networks.
“As it stands now, it’s a security dumpster fire,” Williams says. “This is one of the scariest things I’ve ever seen from an enterprise security standpoint.”
Updated 12:15 pm ET, June 7, 2024: Following criticism from the security and privacy community, Microsoft announced on Friday that it would turn off Recall by default and institute additional security measures.
