Another solution which is often considered a security boundary or a security technology is kernel mode
code signing
this technology disables loading a driver that hasn't been digitally signed in 64 bit Windows systems.
This constituted a rather serious vulnerability from the beginnings of the system.
Ever since Windows 95 the problem was that the majority of critical errors loose screens were a result
of an unstable driver.
Drivers usually operate in the kernel mode and so have direct control over devices
driver bug causes the entire system to hold from a user's perspective.
It seems like a question of Windows malfunctioning.
This had to be fixed somehow.
While moving to a 64 bit environment servers today are all exclusively 64 bit as Will client systems
be in the future.
Microsoft decided to sort the situation
effective troubleshooting requires identifying a drivers manufacturer first the manufacturer can then
be told how to fix the bugs reprogram is not signed.
Contact is nearly impossible
many modules in the program's code don't contain any fingerprinting or contact information.
And even if they do the information is arbitrary a digital signature using a certificate allows a clear
identification of a software creator.
How does kernel mode code signing work.
At the systems start a list of revoked and block drivers is loaded.
This is something along the lines of an exclusion list.
If a driver can be found on a list and attempt to load it will be blocked.
This solution is an interesting idea.
The future of operating systems will probably involve granting explicit permissions to launch some programs
all applications will be blocked by default.
The history of firewalls was much like this firewalls used to explicitly allow all traffic Microsoft
would release for example a security bulletin on dealing with the Slammer worm that advised users to
block port 1 3 7 in parameter firewalls and people would do this.
It seemed that 10 to 15 years ago all ports rope and by default and only selected ports were blocked
day it's the other way around.
All ports are closed and only selected ports are open the same solution could be employed for software
let's return the kernel mode code signing
before a driver is launched its signature is verified.
The signature has to be valid.
The procedure also verifies whether a certificate was used for the signing of the driver has been issued
by an appropriate certification center certificate cost about $100.
It's not about entering a loyalty rewards scheme.
The goal is to uniquely identify our programs manufacturer
kernel code signing has also been a target for attackers in attack that got a lot of attention was one
that was run by Joanna Rutkowski who became quite well known after that
kernel mode code signing is not a rogue driver proof technology to run an attack of this type.
It's enough to purchase an appropriate certificate.
The technology doesn't offer a future for blocking modification of disk files either
another solution that is often seen as a security technology and which was initially marketed by Microsoft
as such is User Account Control will dedicate one of the next modules to it.
Well let's now try to find out if this technology really defines a system security boundary.
User Account Control aims to ensure that programs aren't run with escalated permissions.
Administrator privileges
even the programs launched by an administrator shouldn't be excluded from this rule just had to explicitly
allow a program to gain administrator privileges attempting to launch a process will display a pop up
box asking if you really want to run it and the whole screen will be greyed out.
If you wait long enough you'll see for example that the system clock has stopped background image as
a bitmap of the current screen.
All these operations are there to make you take notice of a security critical question.
Do return to your work need to react in some way to the displayed message.
Since you haven't press control alt delete the problem could have been displayed by any process.
It's easy to create a program that will display a question that looks like a legitimate system morning.
If another process displays the window the standard user will be asked to submit administrator credentials.
In this way a user gives administrator credentials to a malicious process.
That's my User Account Control is not a security boundary.
It's simply an additional feature that can be worked into the structured protection model we've mentioned
earlier.
Its goal is to disable or hinder the automatic infecting of computers by programs that require administrator
credentials.