Re: Windows Platform Binary Table (WPBT) - BIOS PE backdoor

From: Pedro Ribeiro <pedrib@gmail.com>
To: Stefan Kanthak <stefan.kanthak@nexgo.de>
Cc: Kevin Beaumont <kevin.beaumont@gmail.com>,bugtraq <bugtraq@securityfocus.com>
Subject: Re: Windows Platform Binary Table (WPBT) - BIOS PE backdoor
Date:


On 12 August 2015 at 18:33, Stefan Kanthak <stefan.kanthak@nexgo.de> wrote:
> "Kevin Beaumont" <kevin.beaumont@gmail.com> wrote:
>
> [...]
>
>> Microsoft documented a feature in Windows 8 and above called Windows
>> Platform Binary Table.
>
> Cf. <http://www.acpi.info/links.htm> where WPBT is linked to
> <http://go.microsoft.com/fwlink/p/?LinkId=234840> alias
> <https://msdn.microsoft.com/en-US/library/windows/hardware/dn550976>
>
>> Up until two days ago, this was a single Word
>> document not referenced elsewhere on Google:
>>
>>
> http://webcache.googleusercontent.com/search?q=cache:H-SSYRAB0usJ:download.microsoft.com/download/8/A/2/8A2FB72D-9B96-4E2D-A559-4A27CF905A80/windows-platform-binary-table.docx+&cd=1&hl=en&ct=clnk&gl=us
>>
>> This feature allows a BIOS to deliver the payload of an executable,
>> which is run in memory, silently, each time a system is booted.  The
>> executable code is run under under Session Manager context (i.e.
>> SYSTEM).
>
> This sort of feature is NOT new: with Windows 2003 Microsoft introduced
> the loading of "virtual OEM device drivers" during Windows setup, see
> <https://support.microsoft.com/en-us/kb/896453>
>
> AFAIK at least HP and Dell used this method to deploy [F6] drivers
> embedded in their BIOS.
>
> [...]
>
> stay tuned
> Stefan Kanthak
>

One more reason to use Linux, although it sucks to have BIOS level
backdoors like this.
Looks like Lenovo issued updates for the affected systems, and
thankfully no (business) Thinkpads are affected:
https://support.lenovo.com/us/en/product_security/lse_bios_notebook

Regards,
Pedro





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