On 10/28/2022 12:23 AM, Skybuck Flying wrote:
> I have observed the following behaviour of Toshiba Laptop L670/L670D:
>
> 1. Windows 7 is working fine.
> 2. Web browser is working fine.
> 3. All of a sudden black screen.
> 4. All of a sudden reboot.
> 5. The Toshiba Laptop tries to boot into DHCP mode. It's trying to boot from the network.
>
> Here is the strange thing:
>
> 1. I did not tell it to boot from the DHCP network ? So why is this happening ?
> 2. There is no setting in the BIOS to disable DHCP network.
>
> I have seen this behaviour at least twice, perhaps three times by now.
>
> One time could be luck/a bug.
> Two times could be chance.
> Three time is hostile intention.
>
> It does feel a little bit like a potential hack. Somebody might have found a way to reboot this laptop and trigger into DHCP mode, this would imply some kind of ethernet controller/chip hack. It could also be a backdoor into this ethernet chip.
>
> I suspect these hackers might be trying to find some bitcoins or something on this computer.
>
> Other possibilities include: Sudden power loss, perhaps caused by electric cars charging. But this does not explain why the computer would be booting into DHCP mode.
>
> What could explain the DHCP mode is some weird power loss to the harddisk, maybe it doesn't see the harddisk and then tries to boot from DHCP mode, though I find this explanation suspicions and unlikely to say the least.
>
> One time I caught Microsoft scanning computers at 3 o'clock in the night... So perhaps hackers learned a trick from Microsoft and might be trying it with computers running at night.
>
> If it was a hack so far they were not successfull and I simply resetted the computer.
>
> During the DHCP booting attempt the harddisk LED is LIT. Maybe the harddisk is simply hanging at that point... or maybe the harddisk is being scanned with some uploaded software, NOT SURE.
>
> After a HARD reset, everything is fine, I can select windows 7 and everything boots as normal. No traces left so far, except perhaps some power failure mentioning in System Event Log.
>
> This time I noticed what I was doing I was playing this web browser game called: AGAR.IO
>
> and the black screen happened while playing this web browser game.
>
> Futher more I recently cleaned the laptop's internal and it's impossible for it to have been an overheating issue. The laptop WAS NOT OVERHEATING.
> So that can be ruled out completely. I also noticed the air coming from the Laptop was low heat and the chips were low heat.
>
> That is why this reboot is extra Alarming. There was nothing weird going on.
>
> One last possibility is that my repeated "pounding" on the keyboard/keys had something to do with it... perhaps these little tremors on the W key caused the computer to reboot. But at the time of reboot I was not "pounding" the W key.
>
> So it's very suspicious. I have read about possible network driver hacks and possible ethernet chip hacks and even possible backdoors, so I think it's time to issue a security warning, especially the DHCP boot is suspicious.
>
> No boot managers were installed as far as I know, just the one which windows uses by default.
>
> This laptop has real license from Microsoft, so no hacked version of Windows 7.
>
> So my last final warning and advise to you is
>
> DO NOT LEAVE YOUR COMPUTER ON AT NIGHT, ESPECIALLY IF YOU HAVE PASSWORD OR BITCOIN PRIVATE KEYS ON YOUR COMPUTER ! ;)
>
> (I might still do it occasionally to download something with bittorrent, but that is very rare for now :) uTorrent does seem to hang after many hours of activity or maybe it needs to load somewhat to get GUI back but for now I do not consider BitTorrent to be an issue ! ;))
>
> Bye for now,
> Skybuck ! =D
>

A BIOS follows a boot priority list.

Netboot is usually at the bottom of the list.

You can certainly move Netboot up in the boot list,
but since almost nobody uses Netboot, this is not
a normal thing to do.

There is usually an entry in the devices section
of the BIOS, which can help "disable" the network
while in the BIOS only. There is a device disable
(you don't want that), but there is a network stack
for the NIC (you might want to disable that one).
Without a BIOS-level network stack, it cannot Netboot.

In any case, what the symptoms tell me, is the
hard drive in the laptop, the processor in the
hard drive has stopped responding to SATA commands
on the data cable. Switching off the power to the
hard drive, is how you recover from one of those events.

A typical sequence is, the hard drive stops responding,
the OS crashes on a delayed write failure, the computer
reboots after the kernel panic, the hard drive is still
not responding, so the BIOS tries Netboot instead
(as it might well be the only remaining live media).

If you have a spare drive, you can clone the existing
drive to the spare drive, and use the spare drive for
a while. Then see whether the problem is solved.

On desktop systems, issues of this sort can be caused
by chaining too many Molex power extenders in a row.
That can cause a disk drive to not respond (it's
sitting in reset state). This is unlikely to happen
in a laptop, as the user has little opportunity to mess
up the hardware. Laptops are too compact, to allow a lot
of home experimentation.

*******

Summary:

Change the hard drive, and retest.

There could be something wrong with the internal power
rail being used by the drive. This would be +5V on a
2.5 inch drive. If the BIOS has a "hardware monitor",
you could check the +5V measured value in there. My
Acer laptop with Insyde BIOS, has no hardware monitor,
so this option is not available.

Minimum Nominal Maximum
+4.75 +5.00 +5.25

Paul