Security Experts:

Firmware Zero-Day Allows Hackers to Disable Security Features

A researcher has discovered a zero-day firmware vulnerability that can be exploited by malicious hackers to disable security features on Lenovo, HP and likely other PCs.

Researcher Dmytro Oleksiuk revealed last week that he had identified a privilege escalation vulnerability in the Unified Extensible Firmware Interface (UEFI) present on all Lenovo ThinkPad series laptops. UEFI is the successor of the Basic Input/Output System (BIOS) firmware interface.

According to Oleksiuk, the flaw exists in the System Management Mode (SMM) code of Lenovo’s UEFI and it could be exploited for various “evil things,” including to disable the Secure Boot feature, disable UEFI write protections, and bypass Windows 10 Enterprise security features such as Device Guard or Credential Guard.

An attacker can exploit the firmware vulnerability, dubbed “ThinkPwn,” by copying the exploit to a USB flash drive and executing it from the UEFI shell. The researcher believes the flaw can also be exploited from the operating system.

In its own advisory, Lenovo said it’s investigating the matter, but the vendor has so far determined that the vulnerable code was provided by at least one of its three independent BIOS vendors (IBVs). These IBVs take the code provided by chip vendors such as AMD and Intel and customize it for specific computers.

“The package of code with the SMM vulnerability was developed on top of a common code base provided to the IBV by Intel. Importantly, because Lenovo did not develop the vulnerable SMM code and is still in the process of determining the identity of the original author, it does not know its originally intended purpose,” Lenovo said. “But, as part of the ongoing investigation, Lenovo is engaging all of its IBVs as well as Intel to identify or rule out any additional instances of the vulnerability's presence in the BIOS provided to Lenovo by other IBVs, as well as the original purpose of the vulnerable code.”

Oleksiuk has confirmed that the vulnerable code comes from Intel, but says the company addressed it in mid-2014 – although it’s unclear if Intel actually knew about the issue.

Lenovo noted that this is an “industry-wide” problem and someone has already confirmed that the vulnerable code is also present in HP Pavilion laptops.

The researcher disclosed the details of the vulnerability before Lenovo got a chance to fix it. The vendor said Oleksiuk refused to collaborate, while the researcher claims he agreed to help Lenovo, but the company refused to accept his “terms and conditions.”

Related: Pre-installed Lenovo Bloatware Causing More Security Problems

Related: EFI Zero-Day Exposes Macs to Rootkit Attacks

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.