5 ms·

I have always used the DOS/FreeDOS method to update my Dell firmware. Seems silly to let an insecure OS such as Windows have write access to the BIOS. It woul

I have always used the DOS/FreeDOS method to update my Dell firmware. Seems silly to let an insecure OS such as Windows have write access to the BIOS. It would provide an easy path to the holy grail of malware persistence.

secondcoming 6y ago
Every time I've updated the BIOS on my Dell laptop it's been done on the next boot, before Windows starts.
- orev 6y ago
  The update process that runs in the OS would need to use the driver at issue here to write the new firmware into flash at some staging location. After that is done, then you reboot, and the chips see there’s a staged update and applies it.
  - cesarb 6y ago
    That's not how UEFI capsule updates (which AFAIK is what modern Dell computers use) work. The update is written to the EFI partition, the computer reboots into an EFI updater which loads the update to RAM and tells the BIOS where it is, the computer then reboots again and the BIOS itself loads the firmware update from the staging location in RAM and writes it to flash (which is still unlocked at that point in the boot sequence). At no point does anything other than the BIOS write to the flash.
    - chenxiaolong 6y ago
      That's matches what I've observed on my ~2017 Dell XPS. On Linux with fwupd (and Windows), it would write the updater to the EFI partition and then set it as the default boot entry for the next boot. I had to manually add Dell's certificate to the EFI "db" variable when I switched to using custom secure boot keys.
- brian_herman 6y ago
  Even on Debian 11 also!
dr-detroit 6y ago
Imagine working at a company.
vetinari 6y ago
Neither FreeDOS nor Windows have direct write access to the BIOS. They use the UEFI capsule mechanism (i.e. let UEFI update itself on the next reboot).
naikrovek 6y ago
i find it crazy that you think DOS is secure when compared to windows. or anything else, really.
- simondotau 6y ago
  There’s certainly no question that DOS can be exploited, on the other hand DOS has fewer moving parts. And the boot device is usually freshly imaged from the source.
- yjftsjthsd-h 6y ago
  No networking, no multitasking, nobody writing new malware for it.
- fuzzfactor 6y ago
  For those using the traditional DOS-style approach, there has never been a reason or need for any Dell-supplied Windows apps which can compromise the firmware, even upon reboot. Allowing only the local manual console operator to do the deed, and only when NOT booted to Windows or Linux always gave an extra layer of security by comparison. Now we know the Windows way was far less secure than we thought, although it did seem like an obvious security compromise when they first started trying to update BIOS from Vista in addition to the DOS way. Dell has traditionally provided BIOS firmware updates primarily in DOS-executable .EXE form, with additional Windows apps or Dell Update Package approaches becoming available over the decades as the functional reliability was thought to be almost comparable when attempting to replace the ROM file from Windows. The most reliable way to update your firmware has always been to turn off the PC, disconnect the HDD or SSD, then boot to DOS using a floppy, CD, or USB device which contains the flashing program and the ROM file. Run the BIOS flash program from the DOS command line like usual. The equivalent on UEFI motherboards is to boot to the UEFI Shell itself, which if built-in may just come up by default if no drives are connected. Otherwise you will need to supply your own Shell64.efi on a storage medium in a recognized filesystem like FAT32 which UEFI is required to read from. In shell64.efi you will be in a DOS-like command line then you run the vendor-supplied UEFI-executable .EFI program also on your storage media, which then applies the updated ROM file just like it would in DOS. But no operating system needed or wanted, not even DOS any more. Dell example option 1.3.1: https://qrl.dell.com/Files/en-us/Html/Workstations/DellPrecisionR7910/BIOS%20Update.html https://qrl.dell.com/Files/en-us/Html/Workstations/DellPreci... Other motherboards have had a built-in flash routine for some time now, where it recognizes a proper ROM file on a FAT32-formatted USB drive, and you can flash it with no OS necessary either. Also, the FreeDOS approach is just the DOS that is used for distribution to avoid copyright issues. Most of the updates distributed with a FreeDOS platform were usually developed & tested using MS-DOS, and you may have better luck burning the FreeDOS version to floppy, CD, or USB, then copying the vendor executables & files to equivalent MS-DOS-booting media rather than the supplied FreeDOS-booting approach.

secondcoming 6y ago

Every time I've updated the BIOS on my Dell laptop it's been done on the next boot, before Windows starts.

orev 6y ago
The update process that runs in the OS would need to use the driver at issue here to write the new firmware into flash at some staging location. After that is done, then you reboot, and the chips see there’s a staged update and applies it.
- cesarb 6y ago
  That's not how UEFI capsule updates (which AFAIK is what modern Dell computers use) work. The update is written to the EFI partition, the computer reboots into an EFI updater which loads the update to RAM and tells the BIOS where it is, the computer then reboots again and the BIOS itself loads the firmware update from the staging location in RAM and writes it to flash (which is still unlocked at that point in the boot sequence). At no point does anything other than the BIOS write to the flash.
  - chenxiaolong 6y ago
    That's matches what I've observed on my ~2017 Dell XPS. On Linux with fwupd (and Windows), it would write the updater to the EFI partition and then set it as the default boot entry for the next boot. I had to manually add Dell's certificate to the EFI "db" variable when I switched to using custom secure boot keys.
brian_herman 6y ago
Even on Debian 11 also!

dr-detroit 6y ago

Imagine working at a company.

vetinari 6y ago

Neither FreeDOS nor Windows have direct write access to the BIOS. They use the UEFI capsule mechanism (i.e. let UEFI update itself on the next reboot).

naikrovek 6y ago

i find it crazy that you think DOS is secure when compared to windows. or anything else, really.

simondotau 6y ago
There’s certainly no question that DOS can be exploited, on the other hand DOS has fewer moving parts. And the boot device is usually freshly imaged from the source.
yjftsjthsd-h 6y ago
No networking, no multitasking, nobody writing new malware for it.
fuzzfactor 6y ago
For those using the traditional DOS-style approach, there has never been a reason or need for any Dell-supplied Windows apps which can compromise the firmware, even upon reboot. Allowing only the local manual console operator to do the deed, and only when NOT booted to Windows or Linux always gave an extra layer of security by comparison. Now we know the Windows way was far less secure than we thought, although it did seem like an obvious security compromise when they first started trying to update BIOS from Vista in addition to the DOS way. Dell has traditionally provided BIOS firmware updates primarily in DOS-executable .EXE form, with additional Windows apps or Dell Update Package approaches becoming available over the decades as the functional reliability was thought to be almost comparable when attempting to replace the ROM file from Windows. The most reliable way to update your firmware has always been to turn off the PC, disconnect the HDD or SSD, then boot to DOS using a floppy, CD, or USB device which contains the flashing program and the ROM file. Run the BIOS flash program from the DOS command line like usual. The equivalent on UEFI motherboards is to boot to the UEFI Shell itself, which if built-in may just come up by default if no drives are connected. Otherwise you will need to supply your own Shell64.efi on a storage medium in a recognized filesystem like FAT32 which UEFI is required to read from. In shell64.efi you will be in a DOS-like command line then you run the vendor-supplied UEFI-executable .EFI program also on your storage media, which then applies the updated ROM file just like it would in DOS. But no operating system needed or wanted, not even DOS any more. Dell example option 1.3.1: https://qrl.dell.com/Files/en-us/Html/Workstations/DellPrecisionR7910/BIOS%20Update.html https://qrl.dell.com/Files/en-us/Html/Workstations/DellPreci... Other motherboards have had a built-in flash routine for some time now, where it recognizes a proper ROM file on a FAT32-formatted USB drive, and you can flash it with no OS necessary either. Also, the FreeDOS approach is just the DOS that is used for distribution to avoid copyright issues. Most of the updates distributed with a FreeDOS platform were usually developed & tested using MS-DOS, and you may have better luck burning the FreeDOS version to floppy, CD, or USB, then copying the vendor executables & files to equivalent MS-DOS-booting media rather than the supplied FreeDOS-booting approach.