Hardware Architecture

Video Activity
Join over 3 million cybersecurity professionals advancing their career
Sign up with
Required fields are marked with an *
or

Already have an account? Sign In »

Time
15 hours 43 minutes
Difficulty
Advanced
CEU/CPE
16
Video Transcription
00:01
>> Let's take a look a little bit
00:01
closer at some of the elements that are in the TCB,
00:01
starting with hardware architecture.
00:01
Now, I want to be really clear,
00:01
in this section,
00:01
we're not going to get into the details
00:01
of the different types of RAM or we're not going to get
00:01
into anything really in-depth
00:01
with processors or operating system kernels.
00:01
We're going to just reference them.
00:01
We'll talk about them at a high level.
00:01
This exam, again, not a technical exam.
00:01
If you're counting the pins on
00:01
a processor or on a stick of memory,
00:01
not the right test.
00:01
We want to just understand is
00:01
the elements of a TCB as they
00:01
come together and really just
00:01
understanding their role within a system.
00:01
Don't go too deep here.
00:01
Now when we start the elements of a system,
00:01
the CPU is going to be the most
00:01
significant because this is
00:01
where all the processing happens.
00:01
You're going to have registers which are areas of
00:01
high-speed memory that store instructions
00:01
the processors are going to need.
00:01
We also have arithmetic logic units.
00:01
There's control unit, there's math co-processor,
00:01
they're just various elements that make
00:01
up the processor that work together.
00:01
We've got memory, different types of memory.
00:01
We've got RAM and ROM.
00:01
When we talk about buses,
00:01
like the system bus,
00:01
we're talking about the pathways on
00:01
your motherboard that data can travel.
00:01
Then of course, we have to think about storage.
00:01
Now not all of
00:01
these elements are part of the trusted computing base.
00:01
Storage, for instance,
00:01
your hard drive, optical drives,
00:01
your solid-state drives,
00:01
>> which are hard drives too often,
00:01
>> but they can be magnetic or solid-state.
00:01
Those are not elements of the TCB.
00:01
If I was just looking at the TCB here,
00:01
we'd focus on the processor and we'd focus on RAM.
00:01
Now, focusing on the processor specifically,
00:01
because the processor is one of
00:01
the most trusted elements of a system,
00:01
we've got to make sure that
00:01
the processor is protected and is
00:01
trustworthy and isn't compromised
00:01
by rogue applications or services.
00:01
The processor has two separate modes
00:01
in which it can operate.
00:01
One is called kernel mode
00:01
and the other's called user mode.
00:01
Now there's some other names for
00:01
kernel mode could be called privileged mode,
00:01
supervisor mode,
00:01
but kernel mode is one that I
00:01
hear most frequently I think.
00:01
It's almost like if you're a network administrator,
00:01
you don't come in at 8:30 in
00:01
the morning and log on as network admin.
00:01
Like I would come in and log in as Kelly Hindrahin,
00:01
Kelly H, whatever my user account is.
00:01
Then when I need to do
00:01
administrative functions I would elevate my privilege.
00:01
I don't just stay logged in all days and administrator.
00:01
Well, neither does the processor.
00:01
When a processor needs to perform elevated privileges,
00:01
it escalates from user mode to kernel mode.
00:01
Those escalated privileges are performed and
00:01
then the processor operates back down to user mode.
00:01
At that level, the default mode of
00:01
user mode has less privileges.
00:01
That even if there's some compromise of a service,
00:01
then the damage is very limited.
00:01
That's the CPU protection mode.
00:01
Now, I'll just mention with RAM,
00:01
the different types of RAM that we have.
00:01
One of the things I'll mention is cache.
00:01
Cache is an area of
00:01
very high-speed memory for
00:01
functions that are likely to be necessary,
00:01
we have to make sure that cache is protected.
00:01
Because if it does get modified,
00:01
then users can be redirected to
00:01
different resources and so on.
00:01
We also have to think about virtual memory,
00:01
which is a file actually stored on the hard drive,
00:01
but it's designed to work like RAM.
00:01
Because that hard drive isn't a trusted element, well,
00:01
we have memory written to
00:01
an untrusted element that can be an issue,
00:01
so we're just aware of that for
00:01
RAM and for memory in general.
00:01
Like we said, storage
00:01
isn't part of the trusted computing base.
00:01
As a matter of fact, you don't even have to
00:01
have storage devices on a system.
00:01
I could boot up to some sort of external media,
00:01
and I can store all my data in the Cloud,
00:01
and a lot of systems are moving that way.
00:01
Yeah, I think it's certainly as a technician,
00:01
as a network admin,
00:01
security admin to understand some of
00:01
the different elements and how they come into play.
00:01
But you don't need to get into the details here.
00:01
I mentioned system buses,
00:01
these are pathways and if you look at a motherboard,
00:01
you can see the pathways on
00:01
>> the board between components.
00:01
>> Again, not an A-plus class,
00:01
but I did feel like I ought
00:01
to at least reference some of these hardware elements.
00:01
Your system buses are not generally
00:01
considered to be part of the trusted computing base.
00:01
In this section, we covered the various elements of
00:01
hardware and we said out of this four hardware,
00:01
the CPU and memory are
00:01
the most important elements
00:01
of the trusted computing base.
00:01
If either of those are compromised,
00:01
then my system is compromised.
Up Next