The recent Lenovo LSE blunder made most of the world aware of Windows WBPT ACPI table and how the firmware injects an executable into the OS, a feature of Windows that all OEMs are likely using. While the media is wondering about WBPT and why it’s not prominently displayed on many web sites, Xeno of LegbaCore pointed out that Alex Ionescu gave a talk at SyScan 2012 on this specific topic:
ACPI 5.0 Rootkit Attacks Againts Windows 8
This talk will disclose certain new features of the ACPI 5.0 Specification which is now public and was primarily designed to support ACPI on ARM Embedded SoCs for the upcoming release of Windows 8. Some of these new features have important security considerations which have not been traditionally monitored by security products and/or users, specifically in the areas of covert code execution at Ring 0 privileges.
Thanks for reminding us, Xeno!
Today US-CERT issued a warning about Lenovo’s LSE:
Lenovo Service Engine (LSE) BIOS Vulnerability
Certain Lenovo personal computers contain a vulnerability in LSE (a Lenovo BIOS feature). Exploitation of this vulnerability may allow a remote attacker to take control of an affected system. Users and administrators are encouraged to review the Lenovo Security Advisories for notebooks and desktops and apply the necessary updates and mitigations.
An interesting find, potentialy scary if misused. See the Ars Technical and YCombinator stories for discovery. What is Windows’ ‘wpbbin.exe’, and how/when is it used? There’s one reference to it on Microsoft.com in a DOC related to WPBT, the Windows Platform Binary Table. From one document no longer on the Microsoft web site (saved in Google cache, found on the Ars article):
“A rich set of tools exist to aid Windows provisioning, ranging from driver injection and offline registry management to sysprep imaging tools. However, there is a small set of software where the tools are not enough. The software is absolutely critical for the execution of Windows but for one reason or another, the vendor is unable to distribute the software to every provisioning entity. This paper describes a mechanism for a platform, via the boot firmware, to publish a binary to Windows for execution. The mechanism leverages a boot firmware component to publish a binary in physical memory described to Windows using a fixed ACPI table. The information provided here was originally published in conjunction with the availability of Windows 8. The guidance and requirements to use WPBT functionality has been updated for the Windows 10 timeframe.”
Found while researching the above: Lenovo has security updates for LSE:
LEN 2015-077: Lenovo Service Engine (LSE) BIOS for Desktop
LEN-2015-020: Lenovo Service Engine (LSE) BIOS for Notebook
Lenovo Security Advisory: LEN-2015-020
Potential Impact: Privilege Escalation
Summary: Vulnerabilities have been identified in the Lenovo Service Engine (LSE). Lenovo has released a BIOS update to disable Lenovo Service Engine and a utility to remove services and files left on the system for systems running Windows 7, 8, 8.1 and 10. See below for a full list of notebook systems with LSE installed.