I have admin and limited user account on my PC. I always run in
limited user account, except when installing program and doing other
system maintenance work.

In limited user account, when I install a program, it will pop up a
dialog to ask for admin password.

Suppose that under limited user account, I by mistake downloaded
virus/trojan, can this virus/trojan/key logger steal the admin
password when I try to install a program?

I know that I'll be safe if I switch to admin account to do the
installation.

And yes, there is a possibility that the virus will change the program
I want to install. Let's ignore this possibility for now.

I am running Win7.

Thanks.

wrote:
I have admin and limited user account on my PC. I always run in
limited user account, except when installing program and doing other
system maintenance work.

In limited user account, when I install a program, it will pop up a
dialog to ask for admin password.

Suppose that under limited user account, I by mistake downloaded
virus/trojan, can this virus/trojan/key logger steal the admin
password when I try to install a program?

How does it work? If it can install a keylogger, it already has admin
privileges.

Short answer:

It should not be able to. The elevation prompt is not in your limited
user account, but in the "secure desktop" instead (like your logon
desktop). The system takes a snapshot of your current desktop, darkens
it, and switches to the secure desktop and displays it there - and then
displays the credentials prompt.

However, it might be possible for a compromised limited account to fake
a secure desktop (darkened desktop) with a fake credentials prompt for you.

I know that I'll be safe if I switch to admin account to do the
installation.

If you have a keylogger "installed", how can you assume this?

And yes, there is a possibility that the virus will change the program
I want to install. Let's ignore this possibility for now.

You are only concerned about what can see the admin password?

When you get to the "logon" screen and enter your admin password there,
it is the same thing as the secure desktop offered up in your limited
user account - if your keylogger can do one, it can do the other.

I am running Win7.

I assumed Vista (the group names all say vista) - and I also assume Win
7 is quite similar in this respect.

In message FromTheRafters
was claimed to have wrote:

wrote:
I have admin and limited user account on my PC. I always run in
limited user account, except when installing program and doing other
system maintenance work.

In limited user account, when I install a program, it will pop up a
dialog to ask for admin password.

Suppose that under limited user account, I by mistake downloaded
virus/trojan, can this virus/trojan/key logger steal the admin
password when I try to install a program?

How does it work? If it can install a keylogger, it already has admin
privileges.

Keyloggers can run as a limited user but will only be able to intercept
activity that happens within that user's context and won't see what
happens in other contexts, including UAC elevated applications.

Short answer:

It should not be able to. The elevation prompt is not in your limited
user account, but in the "secure desktop" instead (like your logon
desktop). The system takes a snapshot of your current desktop, darkens
it, and switches to the secure desktop and displays it there - and then
displays the credentials prompt.

Don't forget the number of folks who set UAC to not use a secure
desktop, these people may not even have this level of protection.

In article , dave-
says...

.........

Keyloggers can run as a limited user but will only be able to intercept
activity that happens within that user's context and won't see what
happens in other contexts, including UAC elevated applications.

Short answer:

It should not be able to. The elevation prompt is not in your limited
user account, but in the "secure desktop" instead (like your logon
desktop). The system takes a snapshot of your current desktop, darkens
it, and switches to the secure desktop and displays it there - and then
displays the credentials prompt.

Don't forget the number of folks who set UAC to not use a secure
desktop, these people may not even have this level of protection.

Sofisticated malware can abuse
security vulnerabilities of various software, including OS,
related to privilege escalation.

All OSs, not limited to Windows, and many of applications
publish often, or time by time security patches,
addressing privilege escalation threat.

Some of them are publicly known among hackers for longer time
before getting fixed.


--
Poutnik

On Sun, 19 Dec 2010 18:56:37 -0800, Dave Warren
wrote:

Don't forget the number of folks who set UAC to not use a secure
desktop, these people may not even have this level of protection.

How can I check to make sure that UAC is set to use a secure
desktop? I only found one screen to control UAC setting, and there is
no mention of secure desktop there. Thanks.

wrote:
On Sun, 19 Dec 2010 18:56:37 -0800, Dave Warren
wrote:

Don't forget the number of folks who set UAC to not use a secure
desktop, these people may not even have this level of protection.

How can I check to make sure that UAC is set to use a secure
desktop? I only found one screen to control UAC setting, and there is
no mention of secure desktop there. Thanks.

It's in the registry
(HKLM/Software/Microsoft/Windows/CurrentVersion/Policies/System), or
could be accessed in security policies (secpol.msc).

Which OS version are you using again?