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Computer Forensics
Presented by: Marcus Lawson J.D. President
Josiah Roloff ENCE Vice President
Global CompuSearch LLC
Spokane WA (main office) 509-443-9293
Portland OR 503-542-7448Sacramento CA 916-760-7362Palm Springs (San Diego) 760-
459-2122
Digital evidence is…- Hard drives - DVDs/CDs- Floppy Diskettes - Flash cards/thumb drives- GPS devices - Mobile devices- Smart phones - Gaming devices- Scanners/copiers/printers - Cameras/Camcorders
Overview:
When a file is deleted, is it really gone?When a file is “deleted” only pointers to that file are removed. The data remains in the same place on the hard drive indefinitely unless overwritten by new data.
Allocated vs. Unallocated file space
How do we get at the relevant data we need?
Forensic Tools:Keyword searching
Scripts
Sorting by date
Sorting by type
It’s not me! I’m being set up!
Who is responsible????
Timelines of use (1) how they are done(2) what they reveal
The Forensics Tools – How they work
The Examination Process
Timeline Analysis: Chat occurring on July 14, 2006
Admission of Digital Evidence
Tools that are validated versus those that are not (Casey Anthony)
Examiner qualifications and opinion vs. factual testimony
Documentation of findings by the examiner
The answers to the questions should be the same regardless of who is asking them
Motive: Girlfriends, boyfriends and secret lovers?
Motive: Creepy paraphilias?
Planning: Buying scuba belts on Ebay?
Planning: Studying tide currents in the bay?
Timing: Your cell phone will rat you out every time!
Case Example : OR vs. Kim
Case TypesHomicide
1. Is it of a child?
2. Is it pornographic?
Web surfing
File sharing
Possession vs. Receipt vs. Distribution
Case StrategiesChild Pornography
Child pornography cases create special discovery issues
As of August 2006, the defense can no longer obtain copies of media alleged to contain contraband in federal cases under the Adam Walsh Act and must do forensic exams at government facilities.
This creates significant problems for trial prep and adds significant cost to the analysis … a cost that is often paid with public funds.
Discovery & CP cases:
The Order Most states have refused to follow the Adam Walsh model and will allow defense forensic examiners to temporarily possess a forensic copy of the media in question via court order.
If a court order is granted, there are several important issues which should be addressed in the order. (WA State sample order)
Discovery & CP cases:
What is to be provided by the government (forensic copy)
Where the media will be examined and stored (in state)
That no contraband will be copied or removed from the forensic imageThe process to be followed when the case is over
Arson : (computer research)
Robbery : (recovered CCTV)
Vehicular Homicide : (GPS)
DUI : (breathalyzer source code)
Rape : (communications before or after)
Case StrategiesThe Kitchen Sink
Search Warrant Affidavits
[14] We find it particularly significant that the IP addresses from which the qem and foel websites were created were traced to internet subscribers hundreds of miles away from
the Chisms’ home in Nine Mile Falls, Washington. We have explained that a computer that is connected to the internet
can be uniquely identified by its IP number, much like a land-
line phone can be uniquely identified by its phone number. See Forrester, 512 F.3d at 510 n.5. Moreover, we have
repeatedly recognized the utility of using IP address information to investigate child pornography offenders. CHISM v. WASHINGTON STATE
Search Warrant Affidavits
The affidavit submitted by Marcus Lawson, the president of a computer forensic company that examined Todd Chism’s computers similarly admonishes: [T]o have any success as an Internet criminal, regardless of whether one was a thief, a hacker or a child pornography collector, it would be incumbent to use other people’s identities to do so. . . . It is primarily for this reason that relying only on information provided by
the user of a credit card that is associated with criminal activity is inherently unreliable.
CHISM v. WASHINGTON STATE
Search Warrant Affidavits
What is an IP address and why is it so important?
Computers communicate on the Internet because of certain “protocols”. These protocols allow information to be broken down into small packets, transmitted to the computer you choose and then reassembled as the file you intended to send.
Search Warrant Affidavits
IP addresses are globally unique numbers that allow each computer connected to the Internet to have it's own specific address (just like your residence) and really is the only way IP networks around the world can talk with each other without everything becoming a jumbled mess.
Search Warrant Affidavits
File Sharing cases (should have more than one incident)
WWW based cases (subscribers and/or server log files of IP’s)
Credit Card use by itself should not be relied upon (the account information used will typically be correct)
Facebook, Yahoo, Hotmail subpoenas
Search Warrant Affidavits
Static vs. Dynamic IP Addresses
The date of IP connection to the subject address must coincide with the dates documented for the offense
Search Warrant Affidavits
TFA Suchy was able to download 61 files from (the defendant), fifty of which were consistent with child pornography. TFA Suchy used CommView in order to identify the IP address utilized by (the defendant) which was 99.68.129.56.
A search of the American Registry for Internet Numbers (ARIN) online database indicated that IP address 99.68.128.56 is registered to AT&T Internet Services. Results from an administrative subpoena sent to AT&T Internet Services for the date and time the files were downloaded revealed that, at that day and time, the IP address was assigned to the account registered to (the defendant’s mother), 0000 Summer Wind Drive, Brecksville, Ohio 44141.
Search Warrant Affidavits
Offense IP number captured
Subpoena to Internet provider
IP address linked to physical
location on correct dates
Search Warrant
for location is requested
Computer ForensicsIf you believe a case might need forensic assistance:
STOP all use of the device(s)- Preservation request
- Subpoena’s sent asap
Create forensic copies of all electronic devices - An inexpensive insurance
Contact an expert to assist in determining how they can be most helpful