14 August 2007

On User Rights, Safe Mode etc.

Edited for spelling; from...


On Fri, 29 Sep 2006 23:17:02 -0400, "Karl Levinson, mvp"
>"cquirke (MVP Windows shell/user)" wrote in

>>>All operating systems do that. They are designed to launch code at boot
>>>time by reading registry values, text files, etc. Because those registry
>>>values are protected from unauthorized access by permissions, someone
>>>would have to already own your system to modify those values, wouldn't they?

The weakness here is that anything that runs during the user's session is deemed to have been run with the user's intent, and gets the same rights as the user. This is an inappropriate assumption when there are so many by-design opportunities for code to run automatically, whether the user intended to do so or not.

>> Sure, but the wrong entities come to own systems all the time.

>My point is that this one example here doesn't seem to be a vulnerability if
>it requires another vulnerability in order to use it.

Many vulnerabilities fall into that category, often because the extra requirement was originally seen as sufficient mitigation.  Vulnerabilities don't have to facilitate primary entry to be significant; they may escalate access after entry, or allow the active malware state to persist across Windows sessions, etc.

>This isn't a case of combining two vulnerabilities to compromise a
>system; it's a case of one unnamed vulnerability being used to
>compromise a system, and then the attacker performs some other
>action, specifically changing registry values.

>If this is a vulnerability, then the ability of Administrators to create new
>user accounts, change passwords etc. would also be a vulnerability.

OK, now I'm with you, and I agree with you up to a point. I dunno where the earlier poster got the notion that Winlogin was there to act as his "ace in the hole" for controlling malware, as was implied.

>> Defense in depth means planning for how you get your system back; you
>> don't just faint in shock and horror that you're owned, and destroy
>> the whole system as the only way to kill the invader.

>That's a different issue than the one we were discussing. The statement
>was, winlogon using registry values to execute code at boot time is a
>vulnerability. I'm arguing that it is not.

I agree with you that it is not - the problem is the difficulty that the user faces when trying to regain control over malware that is using Winlogin and similar integration points.

The safety defect is that:
- these integration points are also effective in Safe Mode
- there is no maintenance OS from which they can be managed

We're told we don't need a HD-independent mOS because we have Safe Mode, ignoring the possibility that Safe Mode's core code may itself be infected. Playing along with that assertion, we'd expect Safe Mode to disable any 3rd-party integration, and would provide a UI through which these integration points can be managed.

But this is not the case - the safety defect is that once software is permitted to run on the system, the user lacks the tools to regain control from that software. Couple that with the Windows propensity to auto-run material either be design or via defects, and you have what is one of the most common PC management crises around.

>Besides, it's a relatively accepted truism that once an attacker has root,
>system or administrator privileges on any OS, it is fairly futile to try to
>restrict what actions s/he can perform. Anything a good administrator can
>do, a bad administrator can undo.

That's a safety flaw right there.

You're prolly thinking from the pro-IT perspective, where users are literally wage-slaves - the PC is owned by someone else, the time the user spends on the PC is owned by someone else, and that someone else expects to override user control over the system.

So we have the notion of "administrators" vs. "users". Then you'd need a single administrator to be able to manage multiple PCs without having to actually waddle over to all those keyboards - so you design in backdoors to facilitate administration via the network.

Which is fine - in the un-free world of mass business computing.

But the home user owns their PCs, and there is no-one else who should have the right to usurp that control. (Even) creditors and police do not have the right to break in, search, or seize within the user's home.

So what happens when an OS designed for wage-slavery is dropped into free homes as-is? Who is the notional "administrator"? Why is the Internet treated as if it were a closed and professionally-secured network? There's no "good administrators" and "bad administrators" here; just the person at the keyboard who should have full control over the system, and other nebulous entities on the Internet who should have zero control over the system.

Whatever some automated process or network visitation has done to a system, the home user at the keyboard should be able to undo.

Windows XP Home is simply not designed for free users to assert their rights of ownership, and that's a problem deeper than bits and bytes.

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