CSI Challenge2012

Provides the backstory behind the crime Provides pertinent information related to the motive

behind the crime Requires the use of 2 software packages:

◦ Forensics Tool Kit (FTK) Version 1.8.0 or 1.8.1

◦ S-Tools Software must be downloaded on your laptop prior to

the competition

Computer Forensics at the CSI Challenge

1. Creating & Opening a Computer Forensics Case 2. Finding Hidden Data in Slack Space or Unallocated

Space 3. Finding a Recently Deleted File4. Finding a File with an Improper File Extension 5. Finding a Stego’d Image or Data Hidden in a JPG File

Evaluation = 5 Critical Skills

How you do it?A. Start FTK and Create a New CaseB. Add evidenceC. Save the case on exiting

Once created you only need to start FTK and open an existing file to continue working on the case

1. Creating & Opening a Computer Forensics Case

A case represents an ‘incident’ You will need to supply:

◦ Name or number of Case◦ Investigator’s name◦ Evidence to be added to the case

New cases can be Created You can Open existing cases previously

created

What is a “Case”?

Should run in “administrator mode”◦ Right-click FTK icon and select “run as administrator”

Or… click properties, and select appropriate option for icon (then you won’t need to repeat each FTK startup)

You may receive a prompt looking for “security device”◦ It’s OK to run without the dongle or security device

USB “dongle” is required to run FTK in “Full Mode” Also might ask for “Code Meter

◦ We’re running in Demo Mode Limits us to 5,000 files in the case, but otherwise fully

functional!

1.A. FTK

Known File Filter◦ Used to “ignore” Known Files◦ OK to load FTK without KFF

KFF Hash Library

Select the appropriate option◦ Generally you’ll either be creating new case or

opening an existing case

Startup

Enter Captions for◦ Case Number

I chose LIPD-2012-0001 Long Island Police Dept., Case 1 of 2012

◦ Case Name Something meaningful

◦ Case Path The folder where case saved on hard drive

The default is the case name

New Case

Enter information about investigator◦ Next screen

Case Log Options◦ Select all options◦ Next screen

Processes to perform◦ Keep default values◦ Next screen

Refine case◦ Accept defaults◦ Next screen

Refine index◦ Accept defaults◦ Next screen

Case setup (cont.)

1.B. Finally… Add Evidence

Click “Add Evidence”

Information to be added to the Case◦ Acquired forensic “image” of Drive

This is a single file, but contains contents of an entire drive!!! Similar to a “zip file” Also referred to as

“image file” Bitstream file Bit-for-bit image file

This “image file” is captured and produced by some forensic software or utility program

Viewed with forensic software which “understands” the file structure It is NOT the same as a GIF or JPEG, which is a PICTURE type of image file and

IS a single file◦ Local Drive (not on CSI 2012)

Attached to the system and addressable as a disk drive For example, the C: or E: disk Could include a CD, DVD, USB, etc..

◦ Contents of a Folder◦ Individual File

What is Evidence

Created earlier by someone using◦ Utility program or Forensic software

Add… Acquired ImageHard Drive “Image files” captured earlier• *.img ending added by

creator• Other endings dependent on software used to create them

Fill in captions◦ Evidence Name/Number

For example, an item number of the evidence list Serial number, if unique

◦ Comments (optional) How acquired or unusual circumstances, etc..

◦ Local Evidence Time Zone -05:00 for NY timezone

Don’t forget about Daylight Savings, if it applies! Used for time comparisons

Adding the Acquired Image File

All Evidence Added.Click “Next”

After clicking “Finish”◦ FTK will Process Files◦ Add them to the case

Finish adding evidence

As part of adding evidence FTK will◦ Keep track of certain items and summarize them◦ Build an “index” of words or terms encountered

Can be used to short-cut a search Can be used to identify words in the entire case

Might provide insight into something not normally considered For example, seeing “gun”, “secret” or “password” as one

of the words in the index

FTK processing added evidence

FTK presents 3 “panes” or “panels” by default◦ Users can configure the placement if desired

FTK provides a list of “summary” buttons with counts◦ Clicking on these can bring up those items in a detail pane so

that you focus on them Bad extensions Image files Deleted files Documents Unknown types Folders Bookmarked items etc

1. Opening a Computer Forensics Case (cont)…what you’ll see

Tabs on the main window◦ Overview◦ Explore◦ Graphics◦ Email◦ Search◦ Bookmark

FTK Panes/Panels

Shows general information about the case◦ Selection in one “pane” shows details in another

“pane” or sub-window

Overview

The “bad extensions” shows 7 files in the bottom pane◦ Selecting one of the files in the bottom pane

shows the contents in the 3rd pane (upper right)

Still in “Overview”

File list contains information about files◦ “X” icon indicates deleted file◦ File extension might indicate one type of file

In reality, another type of file

Overview (cont.)

Shows a “Windows Explorer” style of presentation◦ 3 evidence items seen

Each has sub-items◦ Collapsible or expandable levels

Click on Plus or Minus signs to expand/collapse views Selected item is shown in 3rd pane List of items in the selected item are shown

in bottom (2nd) pane◦ Clicking on one of these will present that item in

the 3rd (top-right) pane

Explore Tab

Icons at top of 3rd pane◦ Alter the “presentation” of data

View as native application Text view Hexadecimal view

◦ It’s the same data, just a different way of viewing it!

Same item… different view of it

The following demonstrates what a user sees if selecting a single file in Explorer Tab

Selecting a single file

Selecting Giants Tickets.doc in Explorer Tab Word document

◦ Really made up of different “components” Selecting the file shows an item list of

components in the file File slack is one of them

Giants Tickets.doc

Shows a pane with thumbnails of images in the currently selected item in your case

Graphics Tab

On the main menu◦ Select “File”

Close Closes the case, remains in FTK

Save Allows you to continue working on the case

Exit Allows you to save (and backup.. Optional) the case Shuts down FTK

1.C. How to exit and save

What is “Slack Space”?◦ It’s disk space which belongs to a file, but is not considered part of

the file’s data Happens because of the way the system allocates disk space to files

◦ How does the system give disk space to a file? By “clusters”… a collection of 1 or more disk “sectors”

A “sector” is 512 bytes (depends on the system) A cluster can be 1, 2, 4, or 8 sectors

Files are written in these clusters, and don’t normally fill up an entire sector or cluster

◦ Two types of “Slack Space” Ram slack

Disk space after the file data and before the end of that sector File slack

Disk space in sectors not used by the file, but belonging to the file

2. Finding Hidden Data in Slack Space

What’s the significance of “slack space”?◦ Contents of RAM slack is generally whatever was

in memory when the file was saved last Might be a password, credit card number, etc.. Or

garbage◦ File slack’s contents can simply be whatever was

left over and not erased when no longer needed by some other file Maybe even another user created that other file

◦ Slack can be used to hide information It’s not visible to users It won’t be “grabbed” by system and overwritten

2. Finding Hidden Data in Slack Space (cont)

In Overview Tab◦ Select Slack/Free Space button

Details pane contains all slack/free space items Full Path describes where that slack space is located

In a specific file◦ It’s part of the file, but not part of the data itself

Comes after the “end of file” marker Do a “search”

◦ Word might appear in “slack”, which might indicate an attempt at hiding something

2. Finding Hidden Data in Slack Space (cont)

Slack: Overview Tab

Start from the “Explore” Tab◦ Locate the file (Giants Tickets.doc)

This file is deleted◦ Highlight the file in Explore

You’ll see: Pane 2 (Lower pane): list of embedded “stuff” in the file,

INCLUDING FileSlack Pane 3 (Upper right): The document as presented by FTK

believing it to be a “Word doc”

◦ Then… in pane 2, select “File Slack” and observe what’s displayed in pane 3

Slack: Specific File

Conduct a search◦ Examine the returned “hits” of the search

Search results (“hits”) indicate where the occurrence was Even if in slack space

Each “hit” also shows the data immediately before and after the “hit” phrase

Slack: Search

Click the SEARCH tab◦ As you type a word or “character string”

Indexed words in case show up◦ Once you’ve found or typed your search term

ADD it to the search You’ll see # of hits You’ll see # of files containing those “hits”

Searching

Select the “hits” for the search item◦ Then “View Item Results”◦ You can use “AND” or “OR” logic when looking for

multiple search items in the same file AND requires all to be present OR requires any one of them to be present

Searching

Indexed vs. Live◦ Indexed

Looks up terms indexed by FTK as evidence was added◦ Live

Looks up a term which wasn’t necessarily in the index built by FTK

Options Text

ASCII UNICODE CASE SENSITIVE REGULAR EXPRESSION

Hexadecimal

Searching

Keep ASCII and Unicode selected◦ They’re both defaults

Default is “ignore case”◦ Won’t care if upper or lower

Will take time◦ Searches the entire case

Regular expressions (NOT IN CSI 2012)◦ A “pattern” to match

Zip code Telephone number Social security number Credit card number

Hexadecimal◦ Look for “non-printable” character values

Live Search

How do you find a deleted file?◦ Overview Tab

Select the summary button for Deleted Files All those files appear in the lower pane

◦ In the Explorer Tab You can view the “directory structure” in the 1st pane Deleted files appear with a red “X” on the icon of the file or folder

◦ Deleted files are often recoverable You need to EXPORT the file

3. Finding a Recently Deleted File

3. Finding a Recently Deleted File (cont)

Why could this be significant?◦ Investigator might recover information the suspect was

attempting to hide or destroy◦ might demonstrate intent to evade detection

It can be demonstrated that a large number of files were deleted Just prior to execution of a search warrant After being interviewed by the police After receiving a call from a victim or conspirator

When taken into account, might provide circumstantial evidence of intent

3. Finding a Recently Deleted File (cont)

How you do it?◦ Overview Tab

Find the Summary Button for “Bad Extensions” Pane 2 lists all those files

◦ Explorer Tab Navigate to the location Pane 2 shows files in that location, with additional information for

each file

4. Finding a File with an Improper File Extension

What is “exporting”?◦ Exporting allows an investigator to

Select a file or files Save them as discrete files to another location outside of the

FTK Case file Why?

◦ Allows investigators to process the exported file “natively” using applications such as Word, Excel, Paint, etc Some files must be processed natively (for example a Stego’d

file must be exported and handled using S-Tools as explained in section 5)

◦ Can burn to a DVD and give to DA or other investigator◦ Allows investigator to consolidate items of interest in one

place and present only those items

Exporting a file

How do you export a file?◦ Select the file (highlight it) in Explorer Tab◦ Right-click on the file, and “Export it”

Exporting a file

How do we find the file?◦ Overview Tab

Click on the “Improper Name” summary button◦ Explorer Tab

In pane 2 (lower pane), improper file extensions will be noted

4. Finding a File with an Improper File Extension

What it means◦ It might be a deliberate attempt to evade detection and hide

information Information might be important

◦ It could also just be a mistake on the part of the user File saved or renamed with the wrong extension

4. Finding a File with an Improper File Extension (cont)

How do I process a file with an “Improper File Extension”?◦ Note the type of file it really should be◦ Export the file◦ Use the appropriate software to view the file, according to the

“real type” of file it is

4. Finding a File with an Improper File Extension (cont)

How you do it?◦ Certain files, such as Windows “BMP” files, can be

“containers”◦ Software such as S-Tools can hide information inside these

“container files”a. Locate a suspected “stego’d” file (the container file)

a. Should be a “BMP” fileb. Export it from FTK’s Case

i. This saves it as a separate file you can then process outside of FTK

c. Use S-Tools to extract the “message file” from the “container file”

i. Password or a passphrase might be required!

5. Finding a Stego’d Image or Data Hidden in a JPEG File

Open S-Tools Drag the “exported” file believed to be a “container

file” into S-Tools

5. Finding a Stego’d Image or Data Hidden in a JPEG File

Right-click the “container” in S-Tools◦ Select “Reveal”◦ When prompted, provide the “passphrase”

Can be a single word or a phrase Could be case sensitive

◦ A “revealed archive” window shows with the hidden file name and size

◦ Select the file in the “Reveal Archive” box Right-click the file you wish to extract from the container

file Save as…

Choose a location You’ve now successfully extracted the hidden message!

5. Finding a Stego’d Image or Data Hidden in a JPEG File (cont)

The result!

5. Finding a Stego’d Image or Data Hidden in a JPEG File (cont)

What it means◦ Definitely a means of evading detection. It’s not accidental!!

1. Data is hidden 2. passphrase might be required

◦ Whoever can be demonstrated to know the passphrase either put the hidden data there, or knew how to retrieve it Guilty knowledge!

5. Finding a Stego’d Image or Data Hidden in a JPEG File (cont)

Best of luck to all CSI Challenge participants!

The End!