Private symbols are not the only way of gleaning more information, other examples I can think of are:
* Checked builds (prior to Win10). These builds shipped de-optimized kernels (e.g. no inlines) typically with copious debug strings which gave away important details. For example I gleaned a lot of knowledge of ALPC MSRPC from the checked build of rpcrt4.dll from Windows 8.
* SDK/DDK headers, especially in the brave new world of insider previews with preview SDK/DDKs there is sometimes information present which should not have been released including "private" information. Again bit of a grey area.
* The private symbols MS do ship. For example a significant proportion of the COM runtime has private symbols, intentionally. You can extract from those a surprising amount of system call structure information.
I'd recommend watching Alex Ionescu's talk at OffensiveCon about how he does reverse engineering on Windows to see many of these things in action. https://www.youtube.com/watch?v=2D9ExVc0G10
I'm not saying any of this would make it a clean-room re-implementation but to say ReactOS cannot possibly have been reverse engineered without just up and copying source isn't true.
edit: Formatting.
It is very possible that some private symbols were part of some leak, but stolen data does not qualify as “shipping” :)
Again, I stand behind my opinion. I eyeballed some of the code side-by-side and there was portions where I could literally see a line-by-line correlation, which I can hardly explain.
Then if reversing the kernel is so doable using legitimate means, why ReactOS is still largely stuck in the early 2000’s, coincidentally where the major leaks happened?
However you seem to want to claim the only place those symbols can come from is being stolen. Of course in this case you use leak as a synonym for stolen, bit leak can just as much mean they were released accidentally by the owner, MS can't steal their own private symbols and release them on the web. I'm sure there's some symbol files traded in private scenarios which are actually taken through non public means but there have been actual incidences of public release of private symbols.
I'm not trying to claim that ReactOS is clean, I have no skin in the game from a project or user perspective. For all I know it might have lifted significant portions of its code from stolen source code or the WRK (which isn't stolen in so much as used without permission, which I'd regard as a totally different thing). I do however take exception to the typical software engineer's view there are somethings which cannot be reverse engineered into a almost similar form.
As to why ReactOS is stuck in the early 2000s, it could be because of all the source code which was stolen and put wholesale into the project. Although if that was the case I'd have expect MS would have sued the living shit of the project by now. It could also be because Windows was and is a very complex OS with many layers which if you're trying to re-implement with a team of 10s to 100s versus 1000s it's going to take a lot of time. It's seems unlikely that the project would spend the millions of man hours to create the abomination that is UWP.
Perhaps the best way to determine if ReactOS is unclean is for MS to open source the Windows Kernel, hell why would you even need ReactOS then :-)
edit: Cleanup.
“Windows NT 4 Service Pack 5 (which had been released unstripped of its symbolic debugging data)”
I’ve seen private symbols for sql server with the guid to switch editions published on the public symbol server for at least 6 months before they were pulled.
Full releases and service packs typically are stripped very well but if you are saying that no private symbols have been published to the public symbol servers then you are incorrect.
The only product that has been effective at stripping symbols traditionally has been office, they were always stripped if you could even get hold of them which was unlikely.
Don’t forget also you could download the checked windows builds which were very open.
Because they don't care or need about the newer MS stuff and also don't have the resources either.
Also they can exploit Microsoft good record of backward compatibility, once you have a good enough lower API compatibility, you can just install a lot of newer MS tech directly on top of it.
Even if that is the case, it's an incredibly poor idea to use them, so that the code ends up with spurious similarities in spite of being (otherwise) cleanly developed.
Because the former is fairly well documented and the latter doesn't seem right in the context of this discussion. If MS themselves messed up and published the symbols through an official channel that's fair game IMO. Although obviously IANAL etc... I'm talking from an ethical perspective, not a legal one.
I don't know much about ReactOS or the NT kernel but we have this type of controversy regularly in the emulation scene and while sometimes it's true that people reuse docs they shouldn't have, a lot of the time people underestimate the skill and cunning of reverse-engineers to figure out how things work without having access to any restricted information.
I think he's saying that even having access to leaked or accidentally released originals is not implicit permission to use it freely. Otherwise any piece of software that was ever legitimately released would be fair game, just throw it at a decompiler and profit.
If you're making a clean room design having so many similarities to the original is unlikely to happen accidentally.
Anybody implementing a clean room design should theoretically have no prior knowledge of the original's inner workings. The specs are written by one person, checked to not include any of the original material by a second one, before being passed to a third to be implemented.
From far enough a piece of wire and an isolation transformer do the same thing. The secret sauce is in that isolation, you can't just shunt it and pretend it's the same.
I don't really subscribe to a belief of absolute morality, but in the context of the discussion, I think that no matter how you got access to that code, if you say that you are reverse engineering it, then copying an implementation is not doing what you are saying you are doing (as well as being copyright infringement).