Hardware makers have lagged behind in protecting even the latest systems from attacks through their ports, leaving users' and companies' systems open to exploit by anyone who can snag some alone time with the targeted system, security firm Eclypsium stated in a report published on January 30.
The attacks exploit the direct memory access, or DMA, feature of some computers and servers which allow peripherals to directly access the system's memory. In a recent test of two modern laptops, security researchers at the firm found that they could easily compromise the systems — one through a port and the other through a supply chain–type attack by opening the case — even though firmware makers have solutions available to mitigate the DMA security issues, says Jesse Michael, principal researcher with Eclypsium.
"This is something has been traditionally difficult for people to fix," he says. "Because even though there are security features and capabilities and protections that are being put into silicon and the hardware by Intel and the chipset vendors, ... it takes a while for the different vendors to write code that enables and actually configures these hardware protections to secure the system before it gets into customer hands."
Not a New Issue
The attacks are not new. In 2016, Ulf Frisk, a security researcher based in Sweden, published PCILeech, a program that compromises systems through ports to give direct high-speed access to a system's memory. Such ports are often used to drive an external monitor, allow a graphics upgrade, or expand memory. A December 2016 video of the attack shows him recovering the FileVault password of a MacBook Air just by connecting his attack system through the Thunderbolt port.
Since 2017, the makers of laptops, workstations, and servers have had the tools to harden their devices against such attacks, but many have not taken the steps to deliver a secure system to end users. Eclypsium's researchers, for example, bought a new Dell XPS laptop — a model introduced in October 2019 — and found that it had PCI-over-Thunderbolt enabled by default. They easily exploited the issue, Michael says.
"While device vendors, chip vendors, and operating system vendors have all developed new controls to defend against these threats, our research shows that many devices with built-in hardware protections continue to be vulnerable," Eclypsium stated in the report.
In December 2019, Dell issued an advisory and mitigation steps for the issue. Other laptop lines are not affected, the company stated.
Giving anyone physical access to a system poses a security risk. Hardening systems against the autorun setting for devices plugged into the USB port, for example, took years and significant hacks at the US Department of Defense to spur action. Leave your laptop unattended in a cafe and someone could plug in a malicious device that compromises the system in minutes.
Yet market pressures are pushing more vendors to adopt DMA to give workers and consumers the ability to plug in an external monitor or the ability to significantly boost graphics power.
"People think of the boundaries of the laptop as the security perimeter, but if you have a modified mouse or keyboard, you are potentially owned," says Eclypsium's Michael. "We want things to go faster and faster, so we are adding capabilities to these externals ports. Now we are bringing all PCI capabilities through this external port, and there are some interesting security ramifications [extending features] outside the case."
The research also demonstrates that such attacks could be a supply-chain danger for companies, if attackers could get several minutes of hands-on access to a system to implant malicious hardware. In their second test, the researchers replaced an HP laptop's wireless card with a programmable development platform, which could modify system RAM during boot, gaining control of the device, Eclypsium stated.
HP issued an updated version of the BIOS to fix the issue last week.
While these attacks are not new, their continued existence underscore that companies need to pay more attention to the firmware of devices they acquire, says Eclypsium. In 2016, Frisk published a tool for exploiting DMA weaknesses in systems. Known as PCILeech, the program allows attackers to target Windows, Linux, and Mac systems.
"PCILeech is capable of inserting a wide range of kernel implants into the targeted kernels — allowing for easy access to live RAM and the file system via a 'mounted drive,'" Frisk wrote. "It is also possible to remove the logon password requirement, loading unsigned drivers, executing code and spawn system shells."
Since then, chipset and firmware vendors have produced solutions to the issues, but often even the latest systems do not have those mitigations turned on, Eclypsium's Michael says.
"We know how to solve it; it is just isn't in everybody's hands yet," he says. "And some vendors, like [the makers of] a gaming laptop, they might not ever put this kind of solution in."