“Researchers have identified a large number of bugs to do with the processing of images at boot time,” writes longtime Slashdot reader jd. “This allows malicious code to be installed undetectably (since the image doesn’t have to pass any validation checks) by appending it to the image. None of the current secure boot mechanisms are capable of blocking the attack.” Ars Technica reports: LogoFAIL is a constellation of two dozen newly discovered vulnerabilities that have lurked for years, if not decades, in Unified Extensible Firmware Interfaces responsible for booting modern devices that run Windows or Linux. The vulnerabilities are the product of almost a year’s worth of work by Binarly, a firm that helps customers identify and secure vulnerable firmware. The vulnerabilities are the subject of a coordinated mass disclosure released Wednesday. The participating companies comprise nearly the entirety of the x64 and ARM CPU ecosystem, starting with UEFI suppliers AMI, Insyde, and Phoenix (sometimes still called IBVs or independent BIOS vendors); device manufacturers such as Lenovo, Dell, and HP; and the makers of the CPUs that go inside the devices, usually Intel, AMD or designers of ARM CPUs. The researchers unveiled the attack on Wednesday at the Black Hat Security Conference in London.
As its name suggests, LogoFAIL involves logos, specifically those of the hardware seller that are displayed on the device screen early in the boot process, while the UEFI is still running. Image parsers in UEFIs from all three major IBVs are riddled with roughly a dozen critical vulnerabilities that have gone unnoticed until now. By replacing the legitimate logo images with identical-looking ones that have been specially crafted to exploit these bugs, LogoFAIL makes it possible to execute malicious code at the most sensitive stage of the boot process, which is known as DXE, short for Driver Execution Environment. “Once arbitrary code execution is achieved during the DXE phase, it’s game over for platform security,” researchers from Binarly, the security firm that discovered the vulnerabilities, wrote in a whitepaper. “From this stage, we have full control over the memory and the disk of the target device, thus including the operating system that will be started.” From there, LogoFAIL can deliver a second-stage payload that drops an executable onto the hard drive before the main OS has even started. The following video demonstrates a proof-of-concept exploit created by the researchers. The infected device — a Gen 2 Lenovo ThinkCentre M70s running an 11th-Gen Intel Core with a UEFI released in June — runs standard firmware defenses, including Secure Boot and Intel Boot Guard. LogoFAIL vulnerabilities are tracked under the following designations: CVE-2023-5058, CVE-2023-39538, CVE-2023-39539, and CVE-2023-40238. However, this list is currently incomplete.
“A non-exhaustive list of companies releasing advisories includes AMI (PDF), Insyde, Phoenix, and Lenovo,” reports Ars. “People who want to know if a specific device is vulnerable should check with the manufacturer.”
“The best way to prevent LogoFAIL attacks is to install the UEFI security updates that are being released as part of Wednesday’s coordinated disclosure process. Those patches will be distributed by the manufacturer of the device or the motherboard running inside the device. It’s also a good idea, when possible, to configure UEFIs to use multiple layers of defenses. Besides Secure Boot, this includes both Intel Boot Guard and, when available, Intel BIOS Guard. There are similar additional defenses available for devices running AMD or ARM CPUs.”
Robin Edgar
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