Does it work like the Unix tradition of running as a non-privileged user? Is it enough to eliminate the need for an antivirus?
Do you need it if you know what you're doing?– Ivo FlipseJul 21, 2009 at 15:08
It is not enough to eliminate the need for an antivirus because it doesn't prevent executables from running, it just asks for confirmation before running them, and only under certain conditions. It it a useful layer of defence though. As an experienced user, I don't run anti-virus, but I do use UAC as that extra bit of protection. On Vista, I don't find it intrustive, especially coupled with Norton's UAC Tool.
It is similar to the Unix tradition of running as a non-privileged user, although not quite the same. When running as non-root in Unix, you typically need to supply the admin password to run privileged commands, wheras with UAC you only need to click an 'allow' button. This is because on Vista/7 the default user is setup as an administrator. If you setup your user as a non-admin, then you'll need to supply an admin password because only administrators can OK a UAC prompt.
Here's another scenario where it is extremely useful: when you're admin of a family PC (or similar) which is used by several people. Set yourself up as an admin, and everyone else as limited users, but don't give them the admin password. This way, only you can do the dangerous stuff that is often the cause of many a family PC failure. You could, of course, do something like this prior to Vista/UAC, but the simple fact is that UAC makes managing this scenario much easier.
Note, I should add, I don't run real-time anti-virus, but I do run regular scans with various tools and anti-spyware.
3You can change the setting so you are always asked for a password, even when running as Administrator.– JoeyJul 21, 2009 at 15:25
Johannes: I don't think this is built into Windows by default, is it? Do you have a link to further information? Jul 21, 2009 at 15:44
1@Charles: you can set this in the Group Policy Editor (search in the control panel). Go to Computer->Windows->Local and select "Security Options". In the list there is an item called "User Account Control: Behavior of the elevation prompt for administrators. Double-click it and change to "Prompt for credentials". OK, Close, Good to go. Jul 21, 2009 at 17:18
2@Fredrik: I has a suspicion is was something to do with Group Policy Editor. Unfortunately, it's not available in "Home" editions of Vista. Jul 21, 2009 at 17:33
UAC asks for permission from the user to do stuff. It doesent stop the user from answering yes when they shouldn't.
2And it provides sod all useful information to the user as to whether they should accept or not. Jul 22, 2009 at 0:07
UAC is definitely not enough to eliminate antivirus programs. I don't use them anyway.
UAC is a massive pain in Windows Vista, but it is alot better in Windows 7
UAC does mimic the unix tradition as you suggest. As to whether it is enough to eliminate the need for antivirus, personally I don't run with any so I vote yes.
However I probably should run some anyway to use a defence in depth strategy.
Works pretty well. Non-intrusive (despite rumors), and easy to work with. I don't use any anti-virus software. It's not necessary when you practice safe-usage habits. Don't browse on unsecured networks, don't download suspicious files, etc.
Some people say it's annoying, but it's useful when you're a power user. For example, you download some small tool that you know shouldn't require admin privileges, but it asks for elevation anyways. That should raise a red flag.
Also, it allows for everyday programs such as your web browser to run in user-space so in case of an exploit, the attacker won't be able to get very far.
UAC is all about virtualizing user permissions. With it, executable code can be run at a higher or lower permission level than the current user.
For instance, when UAC is on Internet Explorer 7 and 8 have a feature called Protected Mode. This causes every bit of code run by a webpage to be run in a very low privilege mode, where the code only has access to things like the user's temporary folder.
Conversely, when you see a UAC prompt where an application is requesting Admin rights, the app is being given virtual admin rights just for that app.
The biggest benefit of UAC is that it allows people to run most things at the standard user permission level, and elevate as necessary. In Windows XP and previous versions of Windows, it was basically required to run everything in the Administrator account because otherwise using Windows was a real pain. The beauty of this is that it reduces the number of targets for malicious software to hit as at any given time there are fewer apps that can take full control of permissions.
None of this means UAC can in any way replace anti-virus software. But, if you're really careful, UAC can make going without anti-virus a lot easier. I certainly feel a lot safer using Windows with UAC on.
We wrote an article about UAC, what it is, how it works, what's the difference between all levels of UAC in Windows 7. You might find it useful: What is UAC & Why You Should Never Turn It Off