Time
4 hours
Difficulty
Beginner
CEU/CPE
4

Video Transcription

00:00
hi and welcome to everyday did or forensics. I'm your host. You said you said that in today's module image analysis, we're gonna go over the study in order feet process.
00:10
So what is the second biography?
00:13
Where some tools that you can use.
00:15
How is son Sunder Bender related to sonography? And what is that? Shady?
00:21
Okay, so what is steganography? We know we have encryption to be able to send it a message with someone not being able to read it. However, do we have a method to send our message but actually hide our secret message?
00:37
While the cool part is humans have been using steganography since back in the day
00:42
during war times, messages will be sent across.
00:45
I like camps.
00:47
That wouldn't really state the true message. Our message was there. But if someone captured that message in between transition from one camp to the other, they will read something in the sense of happiness or
01:00
not really referring to the message. The message had to be modified in some shape or form
01:06
to be able to retreat reveal the true message
01:10
in the image shown on the screen. You can see that they're wiping it with some compound
01:15
to be able to erase the original message and read between the lions.
01:21
Steganography can also be used in the pens and verify if a bill Israel
01:26
the head and message within that ink and the fact that and the in can only be seen at a student rage. So the naked eye. If this $20 bill did not have the UV re lights over it, the ink saying my money would not be showing. So this is also second geography process,
01:44
so the sames concept could be seen in Spy Horse.
01:47
I wouldn't be surprised if the cyber truck comes with the option to hide a hidden compartment for blame for
01:52
the fact that there's a hidden compartment
01:53
and from the naked eye and the visual of outside. It's just a truck,
01:59
but when you go inside, you'll see that it's not just a truck, but it's a Batmobile when you pop up your fame through and right around town.
02:07
So there's a number of sending off processes, methods that remote levels aren't familiar with.
02:13
We've seen him a lot in spy movies.
02:15
They range from the invisible ink as I shown to micro dots and secret messaging or hidden messages in a second letter in a pain teen
02:24
or in anything
02:28
but computers and networks, there's many ways of hiding information. One of the ways is your convert channels. Do those tools use ICMP as a method to establish communication between a malicious user at compromise system?
02:42
We also have hidden mess tax within webpages.
02:45
You might be just looking at a Facebook page, but on the Facebook page is actually the profile off someone from the dirt the black market who is hiding words within the site so his clientele can come in and find it and contacted. In a certain matter, we have hidden files on disk.
03:01
How many of you feel comfortable going into your system directory on your Windows machine?
03:07
We have all also have known ciphers and then hidden files with an audio and visual file.
03:16
Okay, cool. So those were just works like What is it, really?
03:21
So seven geography is
03:23
being able to have that one back. Let's say there's some
03:27
an image. Whatever this files, the contents of the files aren't particularly important.
03:32
However, I want to go ahead and hide a secret message.
03:39
All right. So here's my secret message. Cool thing about staying in Rome fees. You have the option of encrypting your message. Encryption can work on multiple levels.
03:47
You can decrypt the file. You could encrypt your embedded message. You can decrypt the file, you bend a message and the combination over the three
03:58
that's exactly what it is. You take your file and, um, bad your message
04:02
or your content or your script into the filed South
04:06
with the optional walk.
04:10
So if you want an example of how to use, it is really quick. Get live people you can go in pulled on the Riebel.
04:17
Um, it has an image and a text file for you, too,
04:21
in bed and extract from your image drop. And here you can kind of see and play around with the sonography process. I've also shown the documentation to where you can kind of read more about the to itself,
04:36
so bit shaving.
04:39
This is one of the more common centre graphic techniques used today, and this is used within our image files as carriers specifically best described as bits say, shaving because it sets a least that
04:51
from the carrier bit to the value of zero
04:55
so you're least fit is converted to zero. Most of times, least bit is set to zero for each bit in the carry bit.
05:02
Let's say we have a very simple value of 10 on one.
05:09
Then the least significant bit, which is the final one, will be set to zero, so a new value will be 10 ones. Er,
05:16
so the only difference between the first and the old sort of it is that at least the significant bit become zero after the
05:24
alteration.
05:27
The main sense right? You told me about that.
05:30
So the least that is modified.
05:31
Digital images are described in a particular way,
05:35
so each color is a pick, so
05:38
each picked so has the sound bites that defined the color
05:43
using the least significant bit. The color number does not change drink
05:47
drastically,
05:48
so it's not really seen in the human eye.
05:50
Anti viruses and detections would need intelligence on this particular pattern, or algorithm or signature, just for it to be alerted.
05:59
So
06:00
similar concealment is performed an Audiovox. The adjustments are typically so small that the frequency or pitch changes cannot be detected by the human ear. So this is where you'll find those hidden files
06:15
that take a core sample. The Mona Lisa.
06:17
As I stated earlier, each one of these little blocks is
06:20
a picks up.
06:21
Each pixel is related to a pixel number, so in this case, the area that it's highlighting. So as you see the pics of before, I set to 1 44 then it's 1 41 and 81. The values under your decimal numbers are your binary numbers.
06:39
So 1 44 is equivalent to 1001000 So they say, I want to hide the message of 101001
06:47
We have two examples show. Our first example is to change the significant bit to display the message.
06:55
If you do that for the first decimal value and we convert the last listen to thicken bit from zero to warn, we see that our pixel increments from 1 44 to 1 45
07:05
It's on a big change,
07:08
but this is the next one.
07:09
This do the same thing, changed a significant bit of 1 to 0, and we see that our decimal goes to 1 40
07:17
from 1 41 As you can tell, it's a one decimal value difference. The I will not see this changes so so messages could be saved. In this sense, you also don't have to do that the significant bit. You can also do the two significant bit. As you see in the last example,
07:34
it's still not much of a difference in increments, um,
07:38
by two. And then, as you see, anyone really wasn't affected.
07:43
So there might be cases that you're hiding a message and say, Hey, I need you to go check Offset.
07:47
From here to here I've hit in a message in the least significant, but
07:50
on the bits could have just been in that order. Nothing had changed, but the message was still relevant.
07:59
So I hope you enjoyed today's video. We went over. What's demographic is some of the same graphic techniques, talked about a tool that you can pick up on your own and then talked about bit shaving. I hope you enjoyed today's video, and I'll catch the next one

Up Next

Everyday Digital Forensics

In this course, you will be presented with an overview of the principles and techniques for digital forensics investigation in the spectrum of file system analysis.

Instructed By

Instructor Profile Image
Yesenia Yser
Engineering Manager, Security Research & Development at SoFL, Women in Tech Committee Member, University Outreach and STEM Instructor
Instructor