Researchers have discovered a security flaw in the authentication process of the Apple Device Enrollment Program (DEP), an Apple service that helps enterprises enroll iOS, macOS, and tvOS devices in mobile device management systems.
The problem is centered around the authentication required (or not required) for those enrolled devices.
"The vulnerability lets someone send a valid Apple serial number to the server and retrieve the DEP profile," says James Barclay, senior R&D Engineer and lead analyst at Duo Labs, which found the bug.
And that doesn't necessarily mean that the attacker has seen the devices. "The key space is small enough that the attacker could conceivably generate brute-force numbers and submit them in bulk until they get a valid response," explains Barclay. While the DEP profile contains information on networks and privileges that could be useful to expand an attack, the news could be much worse for some organizations with specific MDM configurations.
"Many configurations of MDM don't require further information on the system it's recording," says Rich Smith, director of Duo Labs. "If the MDM server doesn't have authentication requirements, an organization that's dispensing the certificates for their VPN through the MDM server could see an attacker be enrolled, get the certificate and VPN configuration information, and be an authorized device in the network."
And at that point, the malicious device is free to roam the network doing its dirty work with little to slow it down, he says.
As of the time of this posting, there is no evidence that this attack has been used in the wild, Smith says.
Duo Labs, which detailed its findings in a blog post published today, followed a 90-day disclosure policy for the vulnerability, notifying Apple approximately 3 months before issuing their report. Duo will not publicly release the code to exploit the vulnerability, Smith says.
Remediating the vulnerability is not something an individual customer can do much about, Smith says. "It's less a bug and more a flaw; the serial number as the only information used to authenticate a device is the source of the issue."
"Fixing a flaw may be more complex than fixing a bug," he notes.
The serial number is not sufficient for authentication, he says. It's not a "strong enough form of authentication to provide the properties we'd like to see for enrolling in an organization's fleet," Smith says.
Meanwhile, Apple may not have to release a patch for the flaw to users. Barclay points out that the issue exists in server-based code within Apple; remediation may happen at any time, with little or no notice to users of the service. Apple has not yet responded publicly about the flaw.
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