Secure Boot flaws could enable hackers to take control of Dell devices

Security researchers have discovered several vulnerabilities affecting the BIOSConnect feature within Dell Client BIOS. The bugs could enable hackers to run code at the Bios level.

The bugs affect 129 models of enterprise and consumer laptops, tablets, and desktops protected by Secure Boot. Researchers believe more than an estimated 30 million devices are affected.

According to a new report by security researchers at Eclypsium, the chain of flaws gets a CVSS score of 8.3. When used together, these flaws enable a privileged network adversary to impersonate Dell.com and gain arbitrary code execution at the BIOS/UEFI level of the affected device.

This means that hackers could control the device’s boot process and subvert the operating system (OS) and higher-layer security controls. Researchers warned that such code may alter the initial state of an operating system, violating common assumptions on the hardware/firmware layers and breaking OS-level security controls.

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“As attackers increasingly shift their focus to vendor supply chains and system firmware, it is more important than ever that organizations have independent visibility and control over the integrity of their devices,” researchers said.

BIOSConnect is part of SupportAssist and enables users to perform a remote OS recovery or update device firmware. In either case (firmware update or OS recovery), BIOSConnect enables the system’s BIOS to contact Dell backend services over the internet and coordinate the update or recovery process.

Researchers found four vulnerabilities that would enable a privileged network attacker to gain arbitrary code execution within the BIOS of vulnerable machines. These flaws were found on a Dell Secured-core PC Latitude 5310 using Secure Boot. Researchers soon found the problem existed on other Dell laptops and desktops.

The first flaw is an insecure TLS Connection from BIOS to Dell. A hacker with a privileged network position could impersonate Dell and deliver attacker-controlled content back to the victim device.

The remaining flaws concern overflow vulnerabilities allowing arbitrary code execution. Hackers impersonating Dell could deliver malicious content back to the victim machine. Two of these vulnerabilities affect the OS recovery process, while the other affects the firmware update process.

The researchers notified Dell of the flaws. Dell has since issued a security advisory and is scheduling BIOS/UEFI updates for affected systems and updates to affected executables from Dell.com.