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It's not even a "backdoor", it's documented in the datasheet...

http://datasheets.chipdb.org/VIA/Nehemiah/VIA%20C3%20Nehemia... (page 82)

...which along with the already publicly-known microarchitecture of the C3 makes this statement sound like total nonsense:

The rosenbridge backdoor is a small, non-x86 core embedded alongside the main x86 core in the CPU

I remember laughing at this with a few others knowledgeable in x86 when it first came out; a self-proclaimed "security researcher" who somehow failed to RTFM.

There's even a Wikipedia article about it now, with a link to the alternate instruction set documentation: https://en.wikipedia.org/wiki/Alternate_Instruction_Set

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"It's documented in the datasheet" is such a weak excuse for a backdoor.

Documenting a backdoor doesn't make it not a backdoor, just means it's not a hidden backdoor.

The fact that a number of machines shipped with the backdoor accidentally enabled, and nobody noticed for over a decade shows just how dangerous even a documented backdoor can be. The oversight wasn't even detected by someone reading the manual, it was detected by a security researcher who wrote a generic tool to fuzz out such backdoors.

Doesn’t backdoor imply hidden? If it’s clearly documented it’s just a (front)door?

backdoor means a secondary access point that defeats the security features of the primary. In the door analogy, the home owner spends a ton on a lock and camera for the front door but doesn't even have a deadbolt on the back.

Every definition of a “backdoor” in computing implicitly or explicitly considers it hidden/covert.

In the house analogy you don’t see the backdoor when approaching the front. If it was just “an alternative everyone knows about and can be broken easier than the front door” then it probably would have been called “a window”.

Most login forms have a weaker option like a SMS 2FA or password reset fallback. Nobody calls it a backdoor. It’s just a crappy second front door, or window.

I'm probably mistaken, but I've always referred to password resets as backdoors. Is there another term they could be classfied as?

> Is there another term they could be classfied as?

As an advertised feature of the product.

Your personal definition doesn’t match the general understanding of the word and concept. By your definition every window on a house or car is a “backdoor”. Anything with an advertised fallback is a backdoor. And sometimes the “front door” is the back door: getting money from an ATM is less secure than with an ID at the bank teller.

Password resets aren't "backdoors" unless they contain a flaw the defeats any security protections. It's not just that the backdoor is less secure than the front, the backdoor has no security or is so easily defeated the security may as well not exist.

I'm surprised the hidden aspect of backdoor is so forward in folks minds. In my thinking nothing in cyber security is hidden, I drop the obviously present hidden part of backdoor definition when it's used in yhe cyber security context.

No offense but I don’t think you have a clear enough definition in your head and you’re making it up as we go along and you get challenged.

>> I'm probably mistaken, but I've always referred to password resets as backdoors

> Password resets aren't "backdoors" unless they contain a flaw the defeats any security protections.

You really have to make up your mind. It was “always” but then it wasn’t, and even as you put it you’d have been wrong almost every time to call a reset “a backdoor”.

> I'm surprised the hidden aspect of backdoor is so forward in folks minds.

Only because you misunderstand the meaning of the term, as made very clear above. Go through the wiki page for a “backdoor”.

> In my thinking nothing in cyber security is hidden

I wonder what all those security researchers do all day, with everything being so out in the open and known by everyone.

> I drop the obviously present hidden part of backdoor definition when it's used in yhe cyber security context.

You can drop it but then you’re just using the wrong definition and wrong understanding.

no offense taken. i shouldnt have included password resets in my def. it muddied the conversation. covert is part of a def, at least sometimes, but i think its still acurate to drop it. consider a machine with two copies of ssh running, one of 22 with authentication and another on 2222 with an automatic root login. the instance on 2222 would be considered a backdoor, even though its barely hidden. Swap the ports and it's an unauthenticated frontdoor, but i'd still call it a backdoor and expect everyone to know what i mean. the important part is its bypassing securit, not that its hidden.

The Free Software Foundation (FSF) calls the update system used in Windows 10 a "back door" [1], I think because it installs updates automatically. This sounds like nonsense to me, because it implies that I installed a back door on my own machine by enabling automatic upgrades (on Trisquel).

It's meaningful that the Windows 10 install method has no (official) way to disable it, but I don't think making something optional could make it not a back door, if it was one before.

Even when automatic updates are disabled, I'm not going to be reading every update so the effect seems mostly the same, regardless of whether updates are automatic or not.

The FSF's definition of "back door" (at the bottom of the linked page) is "any feature of a program that enables someone who is not supposed to be in control of the computer where it is installed to send it commands" which leaves a lot of ambiguity with the words "supposed to be". I am not sure how to interpret this definition.

[1] https://www.gnu.org/proprietary/proprietary-back-doors.html#...

The FSF definition can be interpreted in absurd ways; a very uncharitable interpretation would classify any network stack connected to the internet as backdoor because random, potentially misdirected packages trigger code exécution on the target machine, even if only to figure out that the packet must be ignored.

I agree with any automatic updates being a back door.

Doesnt really matter which platform, automatic updates are bad news.

On windows it led to clownstrike. On BMW it led to dash ads.

Theres infinite examples of auto updates being an attack vector for OEMs and other bad actors.

Always disable updates on every product. Can always reenable as needed or even sideload updates.

How do you decide when to update?

thats a tough decision if something aint broke, dont fix it. if there is a reason to upgrade, maybe wait until there are good reviews before actually applying it or make a safety backup first

Not really... backdoor just means something that can bypass the main security.

It's just that publicly known backdoors are of very limited usefulness, because people go out of their way to remove, disable, or avoid them. Or worse, use them for their own gains. There have been more than a few cases of governments trying to implement and enforce publicly known backdoors (with keys only the government knows), such as the Clipper cryptography chip in the 90s.

But... just because something is documented, doesn't mean it's publicly known. We have an example here of something obscure enough to be a useful backdoor (assuming someone knew about it).

And while the underlying feature might have been documented, the fact that many BIOSes enabled the feature was not documented anywhere. That does count as hidden.

The documentation was locked away behind NDAs when the faulty BIOS leaving it reachable was discovered. Look at the publication dates.

Was this documentation public at the time? The pdf still does not document the instructions themselves.

It was public at least 4 years before he first announced his discovery:

https://web.archive.org/web/20140130160743/http://datasheets...

yes, AIS was known

sandsifter was lots of noisy PR, but no new encoding findings

AFAIK, sandsifter did find a halt-and-catch-fire instruction on one of the CPUs, but I haven't seen anyone announce which CPU model it was.

It's not as clear cut as you describe it here. In the other old thread you linked there was no real consensus if this should be considered a backdoor or not.

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