Attackers bypass login credentials in corporate laptops
Thanks to the insecure defaults in Intel’s AMT, intruders are able to completely bypass user and BIOS passwords and TPM and Bitlocker PINS to backdoor almost any corporate laptop in a matter of seconds. F-Secure reports a security issue affecting most corporate laptops that allows an attacker with physical access to backdoor a device in less than 30 seconds.
The issue allows the attacker to bypass the need to enter credentials, including BIOS and Bitlocker passwords and TPM pins, and to gain remote access for later exploitation. It exists within Intel’s Active Management Technology (AMT) and potentially affects millions of laptops globally.
The security issue “is almost deceptively simple to exploit, but it has incredible destructive potential,” said Harry Sintonen, who investigated the issue in his role as Senior Security Consultant at F-Secure. “In practice, it can give an attacker complete control over an individual’s work laptop, despite even the most extensive security measures.”
Intel AMT is a solution for remote access monitoring and maintenance of corporate-grade personal computers, created to allow IT departments or managed service providers to better control their device fleets. The technology, which is commonly found in corporate laptops, has been called out for security weaknesses in the past, but the pure simplicity of exploiting this particular issue sets it apart from previous instances. The weakness can be exploited in mere seconds without a single line of code.
The essence of the security issue is that setting a BIOS password, which normally prevents an unauthorised user from booting up the device or making low-level changes to it, does not prevent unauthorised access to the AMT BIOS extension. This allows an attacker access to configure AMT and make remote exploitation possible.
To exploit this, all an attacker needs to do is reboot or power up the target machine and press CTRL-P during bootup. The attacker then may log into Intel Management Engine BIOS Extension (MEBx) using the default password, ‘admin,’ as this default is most likely unchanged on most corporate laptops. The attacker then may change the default password, enable remote access and set AMT’s user opt-in to ‘None.’
The attacker can now gain remote access to the system from both wireless and wired networks, as long as they’re able to insert themselves onto the same network segment with the victim. Access to the device may also be possible from outside the local network via an attacker-operated CIRA server.
Although the initial attack requires physical access, Sintonen explained that the speed with which it can be carried out makes it easily exploitable in a so-called ‘evil maid’ scenario.
“You leave your laptop in your hotel room while you go out for a drink. The attacker breaks into your room and configures your laptop in less than a minute, and now he or she can access your desktop when you use your laptop in the hotel WLAN. And since the computer connects to your company VPN, the attacker can access company resources.” Sintonen points out that even a minute of distracting a target from their laptop at an airport or coffee shop is enough to do the damage.
Sintonen stumbled upon the issue in July 2017, and notes that another researcher also mentioned it in a more recent talk. For this reason, it’s especially important that organisations know about the unsafe default so they can fix it before it begins to be exploited. A similar vulnerability has also been previously pointed out by CERT-Bund but with regards to USB provisioning, Sintonen said.
The issue affects most, if not all laptops that support Intel Management Engine / Intel AMT. It is unrelated to the recently disclosed Spectre and Meltdown vulnerabilities.
Intel recommends that vendors require the BIOS password to provision Intel AMT. However, many device manufacturers do not follow this advice.