Earlier quoted context omitted.
> You seem to think that is unlikely. Why? Because of the single user pc context. I've never seen a dropper that didn't have ring 0 later pull down a payload that escalated privilege. I'm not saying that it isn't possible, but at best it is very uncommon. I understand the better safe than sorry position, but with the context in mind, what safety are you getting by just assuming UID separation failed and going through…
> I've never seen a dropper that didn't have ring 0 later pull down a payload that escalated privilege. Probably because it isn't very useful to the attacker. Pwning the single user's account is sufficient. But I wouldn't bet on that being the case if it happened to me. > what safety are you getting by just assuming UID separation failed and going through the rigmarole of reinstallation? The user data has already bee…
Ring 0 is really important for building a botnet, which provides a very real incentive for the folks that actually write the droppers. Ideally (for the botnet owner) they establish persistence, then sell access by directing the bots to download additional malware under the control of botnet customers. Long story short: you don't get paid as much if you don't have ring 0.
> Most user data is not executable...
I was speaking from the perspective of the real purpose behind all this, protecting user data - and that the horse is already out of the barn. As far as cleanup, you are presupposing a loss of ring 0. If ring 0 is secure then killing all the user processes and performing a snapshot rollback of user space will definitely clear the malware.
> Well, I'm talking about today's legacy...
Ah, well then I agree. If your platform does not have user isolation, then you shouldn't rely on user isolation for security.
> And as wiping the whole system does not add very much cost...
Well we've got a catch-22. Because implementing security practices that do harden the system add a lot more cost to a hamfisted wipe. For example: On my laptop I've got five jails, a maze of netgraph nodes that result in a complex ruleset, host IPS, kerberos authentication and authorization, encrypted filesytems, close integration with TPM and various certificate based credentials. Just assuming that none of that works and doing a system wipe is a lot more work than simply popping in the latest Ubuntu dvd iso... consider the labor of rekeying alone.
So the advice to do a system wipe isn't bad, but it should be prefixed with: "If you've made no effort to secure your system and are completely relying upon the distro provider for security".