I'm greatly disappointed by the number of true techies and semi-techies who have gone into a sort of 'hate UAC' mode. I understand their frustrations; UAC can slow down routine sysadmin activities and break into the flow of your day. But, like seatbelts in a car, it's one of those things that seems like a terrible imposition at first, then just blends into your routine to the point where you hardly think about it. You buckle up and you're safer because you did it. I was one of those guys who hated seatbelt laws when they first appeared. But I got used to it, and now that I've survived a rollover accident because of a seatbelt, I'm pretty glad I did!
I've been running Windows systems according to the least privilege principle ever since Windows NT 4. I call this nonadmin because it's less of a mouthful. And I've been forcing users to do it, and begging my co-administrators to do it, since 1996. But I can't lie: nonadmin was a huge pain in the NT4/W2000/XP/W2003 days; the RunAs utility was a major PITA. You had to use special workarounds to elevate essential Windows tools like the file Explorer. There were a great many programs which didn't work well (or at all!) in a nonadmin context. Running nonadmin was doable ... but only with great self discipline, and a fair amount of pain as you worked through the changes in habits and gained the knowledge required to get it done.
In a corporate setting, it is possible for the administrator to do all the work and leave the regular office users blissfully unaware of the fact that they are nonadmin. But when you're the administrator - as home users and many smallbiz users are - the time and effort required to go nonadmin are just more than most people are prepared to expend. So they ignored the issue. And it was easy enough to do; most folks were completely unaware that MS had already made them administrators during the OS install!
There's another group of power users who were also blissfully unaware of their admin status: application coders and testers. Because they didn't know (or did not care) that they were administrators, it was very easy to write programs in ways that required admin capabilities to run properly. And this perpetuated the problem. It became a catch-22: users were admins because devs were. And devs were admins because users were.
Microsoft needed to break out of this loop, and they knew it. And UAC was born. It's actually an interesting compromise: because of all those legacy applications which require admin privs, MS couldn't simply force all users to a full nonadmin mode, which would have been technically preferable. So UAC strikes a middle ground: you're still an adminsitrator by default. But ... not really.
Márton Anka explains this well, so I will simply summarize: all accounts you create during Vista's setup are still members of the Administrators group. But when these accounts log in, all normal operations are carried out with a Limited User's access level. However, when Vista sees you do something that requires admin privs, it presents the UAC dialog box before it elevates privs for that process only. Unless you are running in the account named Administrator, in which case you never see the UAC prompt. Also note that users created after Vista setup do default to a Limited User status; they can elevate privs via UAC but must type a username and password to do so.
So why do I defend all this, while so many other techies are railing against it? Well, remember my saying how hard it was to run nonadmin with just the RunAs tool? UAC now makes all those difficulties a thing of the past.
I run as a Limited User, so every UAC prompt means I need to enter the name of my admin user, and its password. And I saw quite a lot of UAC while installing Vista, and in the two weeks afterwards. I did get a little sick of it, to be honest. But I kept reminding myself of the pain of RunAs, and I soldiered on. Finally, after setting up all my apps, and making various little tweaks and twiddles here and there (as we all tend to do), and exploring the various new administrative features of Vista ... I noticed that I was hardly seeing the UAC prompt at all.
Fast forward to the present. Though I still keep an XP system handy, Vista is the OS I spend my day in. From here I do of course RDP/VNC/SSH to other systems. As a sysadmin of course I'm always poking my nose into things. But honestly, I think I've seen less than 5 UAC prompts in the last 7 days - and I've installed one new app and upgraded another in that time.
So all that RunAs futzing is gone now - I only need to use RunAs for the rare occasions when I need to have an administrator-level instance of cmd. Instead of me having to remember to elevate my privs, Vista does the remembering for me. And whenever I see the UAC prompt, I pause for a second and ask myself whether I expected this. If I didn't expect it, I can ask the other relevant questions, like:
- Do I recognize the program that wants elevated privs?
- Do I trust it?
- Do I have a reasonable understanding of why it needs elevated privs? (Do I know what it will do with them?)
- Does the action really need to have full unfettered access to my system and data?
If I can't give myself satisfactory answers to these questions, I can just say no. And that's the end of it, clean and simple.
UAC is also providing a lot of back-pressure on program developers and testers to organize their programs and associated data into non-critical areas of the system, and this is a good thing. It means that new programs will be more stable and less risky to run, because developers themselves will not want to be hit with constant UAC dialogs. In the long run, this may be the largest benefit UAC provides.
In summary - UAC makes it easier to run nonadmin, and that's a good thing. It provides incentive for developers to write better code, and that's an excellent thing. I'm a big fan of UAC, and I hope the naysayers will see the light. Just as the seatbelt-haters did.