Gigabyte systems have been identified by the Eclypsium platform for exhibiting suspicious backdoor-like behavior. This discovery marks a recent development in detecting potential security vulnerabilities in Gigabyte systems.
The Eclypsium platform employed heuristic detection methods to identify potential supply chain threats, specifically targeting new and previously unknown compromises of legitimate third-party technology products or updates.
These heuristic methods are crucial in uncovering and addressing emerging threats within the supply chain.
Recent findings have unveiled a concerning issue with the firmware in Gigabyte systems, as it is observed to drop and run a Windows native executable during system startup.
This executable, in turn, proceeds to download and execute supplementary payloads insecurely.
PC Motherboard With Backdoor
Utilizing similar methodologies as other manufacturer-installed vulnerabilities, this feature employs techniques reminiscent of backdoors like Computrace, which malicious actors have exploited.
Additionally, it resembles firmware implants such as:-
- Sednit LoJax
- MosaicRegressor
- Vector-EDK
The presence of this backdoor suggests that it was deliberately designed and implemented with specific functionality in mind. To fully eliminate it from impacted systems, a firmware update would be necessary.
UEFI firmware analysis revealed a file named “8ccbee6f7858ac6b92ce23594c9e2563ebcef59414b5ac13ebebde0c715971b2.bin.”
This file is a Windows Native Binary executable within the UEFI firmware volume identified by the GUID “AEB1671D-019C-4B3B-BA-00-35-A2-E6-28-04-36.”
The UEFI firmware incorporates this Windows executable, saved to disk during the system boot process.
This approach mirrors the frequently employed UEFI implants and backdoors to establish persistence.
In the DXE phase of UEFI firmware booting, the “WpbtDxe.efi” module utilizes the provided GUID to load a Windows executable file into memory.
This file is then installed into a WPBT ACPI table, which is subsequently executed by the Windows Session Manager Subsystem (smss.exe) during the Windows startup process.
Before installing the executable into the WPBT ACPI table, the “WpbtDxe.efi” module verifies whether the “APP Center Download & Install” feature is activated in the BIOS/UEFI Setup.
The .NET-based Windows executable is deployed, retrieves, and executes a separate executable payload.
The specific location from which the payload is obtained depends on the configuration settings.
The executable dynamically fetches and launches the payload from a designated location determined by its configuration.
It is crucial to avoid using plain HTTP for updating privileged code due to its susceptibility to compromise through MITM attacks.
Despite employing HTTPS-enabled options, our observation reveals a flaw in implementing remote server certificate validation, making MITM attacks still possible.
This highlights the need for improved validation mechanisms to ensure the integrity and security of remote server connections.
Despite having a valid Gigabyte cryptographic signature meeting Windows’ code signing requirements, the executable and Gigabyte tools provide limited defense against malicious use when exploited with Living-off-the-Land techniques, as seen in the recent Volt Typhoon attacker alert.
Risks and attack scenarios
Here below, we have mentioned all the risks and attack scenarios:-
- Abuse of an OEM backdoor by threat actors
- Compromise of the OEM update infrastructure and supply chain
- Persistence using UEFI Rootkits and Implants
- MITM attacks on firmware and software update features
- Ongoing risk due to unwanted behavior within official firmware.
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