Lecture20 - The University of Texas at Dallas

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Transcript Lecture20 - The University of Texas at Dallas

Digital Forensics
Dr. Bhavani Thuraisingham
The University of Texas at Dallas
Application Forensics
October 26, 2009
 Email Forensics
- UTD work on Email worm detection - revisited
- Mobile System Forensics
- Note: Other Application/systems related forensics
 Database
forensics, Network forensics (already
- Reference: Chapters 12 and 13 of text book
 Military Forensics Overview
Papers to discuss week of November 2
 Optional paper to read:
- http://www.mindswap.org/papers/Trust.pdf
Email Forensics
 Email Investigations
 Client/Server roles
 Email crimes and violations
 Email servers
 Email forensics tools
Email Investigations
 Types of email investigations
- Emails have worms and viruses – suspicious emails
- Checking emails in a crime – homicide
 Types of suspicious emails
- Phishing emails i- they are in HTML format and redirect to
suspicious web sites
Nigerian scam
Spoofing emails
Client/Server Roles
 Client-Server architecture
 Email servers runs the email server programs – example
Microsoft Exchange Server
 Email runs the client program – example Outlook
 Identitication/authntictaion is used for client to access the
 Intranet/Internet email servers
- Intranet – local environment
Internet – public: example: yahoo, hotmail etc.
Email Crimes and Violations
 Goal is to determine who is behind the crime such as who
sent the email
 Steps to email forensics
Examine email message
- Copy email message – also forward email
- View and examine email header: tools available for
outlook and other email clients
- Examine additional files such as address books
Trace the message using various Internet tools
- Examine network logs (netflow analysis)
 Note: UTD Netflow tools SCRUB are in SourceForge
Email Servers
 Need to work with the network administrator on how to
retrieve messages from the server
 Understand how the server records and handles the
 How are the email logs created and stored
 How are deleted email messages handled by the server? Are
copies of the messages still kept?
 Chapter 12 discussed email servers by UNIX, Microsoft,
Email Forensics Tools
 Several tools for Outlook Express, Eudora Exchange, Lotus
 Tools for log analysis, recovering deleted emails,
 Examples:
- AccessData FTK
- EDBXtract
- MailRecovery
Worm Detection: Introduction
What are worms?
Self-replicating program; Exploits software vulnerability on a victim;
Remotely infects other victims
Evil worms
Severe effect; Code Red epidemic cost $2.6 Billion
Goals of worm detection
Real-time detection
Substantial Volume of Identical Traffic, Random Probing
Methods for worm detection
Count number of sources/destinations; Count number of failed connection
Worm Types
Email worms, Instant Messaging worms, Internet worms, IRC worms, Filesharing Networks worms
Automatic signature generation possible
EarlyBird System (S. Singh -UCSD); Autograph (H. Ah-Kim - CMU)
Email Worm Detection using Data Mining
given some training instances of both
“normal” and “viral” emails,
induce a hypothesis to detect “viral” emails.
We used:
Naïve Bayes
The Model
Test data
Training data
Clean or Infected ?
 Features are based on outgoing emails.
 Different users have different “normal” behaviour.
 Analysis should be per-user basis.
 Two groups of features
Per email (#of attachments, HTML in body,
text/binary attachments)
Per window (mean words in body, variable words
in subject)
 Total of 24 features identified
 Goal: Identify “normal” and “viral” emails based on
these features
Feature sets
Per email features
 Binary valued Features
Presence of HTML; script tags/attributes; embedded
images; hyperlinks;
Presence of binary, text attachments; MIME types of file
 Continuous-valued Features
Number of attachments; Number of words/characters in
the subject and body
Per window features
 Number of emails sent; Number of unique email recipients;
Number of unique sender addresses; Average number of
words/characters per subject, body; average word length:;
Variance in number of words/characters per subject, body;
Variance in word length
 Ratio of emails with attachments
Data Mining Approach
Naïve Bayes
Test instance
Data set
 Collected from UC Berkeley.
Contains instances for both normal and viral emails.
 Six worm types:
bagle.f, bubbleboy, mydoom.m,
mydoom.u, netsky.d, sobig.f
 Originally Six sets of data:
training instances: normal (400) + five worms (5x200)
testing instances: normal (1200) + the sixth worm (200)
 Problem: Not balanced, no cross validation reported
 Solution: re-arrange the data and apply cross-validation
Our Implementation and Analysis
 Implementation
Naïve Bayes: Assume “Normal” distribution of numeric and real
data; smoothing applied
SVM: with the parameter settings: one-class SVM with the radial basis
function using “gamma” = 0.015 and “nu” = 0.1.
 Analysis
NB alone performs better than other techniques
The feature-based approach seems to be useful only when we have
SVM alone also performs better if parameters are set correctly
mydoom.m and VBS.Bubbleboy data set are not sufficient (very low detection
accuracy in all classifiers)
identified the relevant features
gathered enough training data
Implement classifiers with best parameter settings
Mobile Device/System Forensics
 Mobile device forensics overview
 Acquisition procedures
 Summary
Mobile Device Forensics Overview
 What is stored in cell phones
- Incoming/outgoing/missed calls
- Text messages
- Short messages
- Instant messaging logs
- Web pages
- Pictures
- Calendars
- Address books
- Music files
- Voice records
Mobile Phones
 Multiple generations
- Analog, Digital personal communications, Third
generations (increased bandwidth and other features)
 Digital networks
- CDMA, GSM, TDMA, - -  Proprietary OSs
 SIM Cards (Subscriber Identity Module)
- Identifies the subscriber to the network
Stores personal information, addresses books, etc.
 PDAs (Personal digital assistant)
- Combines mobile phone and laptop technologies
Acquisition procedures
 Mobile devices have volatile memory, so need to retrieve RAM
before losing power
 Isolate device from incoming signals
Store the device in a special bag
- Need to carry out forensics in a special lab (e.g., SAIAL)
 Examine the following
- Internal memory, SIM card, other external memory cards,
System server, also may need information from service
provider to determine location of the person who made
the call
Mobile Forensics Tools
 Reads SIM Card files
 Analyze file content (text messages etc.)
 Recovers deleted messages
 Manages PIN codes
 Generates reports
 Archives files with MD5, SHA-1 hash values
 Exports data to files
 Supports international character sets
Papers to discuss: October 28, 2009
 FORZA – Digital forensics investigation framework that incorporate
legal issues
- http://dfrws.org/2006/proceedings/4-Ieong.pdf
 A cyber forensics ontology: Creating a new approach to studying
cyber forensics
- http://dfrws.org/2006/proceedings/5-Brinson.pdf
 Arriving at an anti-forensics consensus: Examining how to define
and control the anti-forensics problem
- http://dfrws.org/2006/proceedings/6-Harris.pdf
Papers to discuss November 2-4, 2008
 Forensic feature extraction and cross-drive analysis
- http://dfrws.org/2006/proceedings/10-Garfinkel.pdf
 A correlation method for establishing provenance of timestamps in
digital evidence
Applications Forensics – Part
Dr. Bhavani Thuraisingham
The University of Texas at Dallas
Information Warfare
and Military Forensics
October 26, 2009
 Information Warfare
- Defensive Strategies for Government and Industry
- Military Tactics
- Terrorism and Information Warfare
- Tactics of Private Corporations
- Future IW strategies
- Surveillance Tools
- The Victims of Information Warfare
 Military Forensics
 Relevant Papers
What is Information Warfare?
 Information warfare is the use and management of
information in pursuit of a competitive advantage over an
opponent. Information warfare may involve collection of
tactical information, assurance that one's own information is
valid, spreading of propaganda or disinformation to
demoralize the enemy and the public, undermining the quality
of opposing force information and denial of information
collection opportunities to opposing forces.
 http://en.wikipedia.org/wiki/Information_warfare
Defensive Strategies for Government and
 Are US and Foreign governments prepared for Information
- According to John Vacca, US will be most affected with
60% of the world’s computing power
Stealing sensitive information as well as critical,
information to cripple an economy (e.g., financial
 What have industry groups done
IT-SAC: Information Technology Information Sharing and
 Will strategic diplomacy help with Information Warfare?
 Educating the end user is critical according to John Vacca
Defensive Strategies for Government and
 What are International organizations?
- Think Tanks and Research agencies
- Book cites several countries from Belarus to Taiwan
engaged in Economic Espionage and Information Warfare
 Risk-based analysis
 Military alliances
- Coalition forces – US, UK, Canada, Australia have regular
meetings on Information Warfare
 Legal implications
 Strong parallels between National Security and Cyber
Military Tactics
 Supporting Technologies
- Agents, XML, Human Computer Interaction
 Military tactics
- Planning, Security, Intelligence
 Tools
- Offensive Ruinous IW tools
 Launching
massive distributed denial of service
Offensive Containment IW tools
 Operations security, Military deception, Psychological
operations, Electronic warfare (use electromagnetic
energy), Targeting: Disable enemy's C2 (c0mmand and
control) system and capability
Military Tactics
 Tools (continued)
- Defensive Preventive IW Tools
 Monitor
Defensive Ruinous IW tools
 Information operations
- Defensive Responsive Containment IW tools
 Handle hacking, viruses.
 Other aspects
- Dealing with sustained terrorist IW tactics, Dealing with
random terrorist IW tactics
Terrorism and Information Warfare
 Terrorists are using the web to carry out terrorism activities
 What are the profiles of terrorists? Are they computer
 Hacker controlled tanks, planes and warships
 Is there a Cyber underground network?
 What are their tools?
- Information weapons, HERF gun (high power radio energy
at an electronic target), Electromagnetic pulse. Electric
power disruptive technologies
 Why are they hard to track down?
- Need super forensics tools
Tactics of Private Corporations
 Defensive tactics
- Open course intelligence, Gather business intelligence
 Offensive tactics
- Packet sniffing, Trojan horse etc.
 Prevention tactics
- Security techniques such as encryption
 Survival tactics
- Forensics tools
Future IW Tactics
 Electromagnetic bomb
- Technology, targeting and delivery
 Improved conventional method
- Virus, worms, trap doors, Trojan horse
 Global positioning systems
 Nanotechnology developments
- Nano bombs
Surveillance Tools
 Data emanating from sensors:
- Video data, surveillance data
- Data has to be analyzed
- Monitoring suspicious events
 Data mining
- Determining events/activities that are abnormal
 Biometrics technologies
 Privacy is a concern
Victims of Information Warfare
 Loss of money and funds
 Loss of shelter, food and water
 Spread of disease
 Identity theft
 Privacy violations
 Death and destruction
 Note: Computers can be hacked to loose money and identity;
computers can be used to commit a crime resulting in death
and destruction
Military Forensics
 CFX-2000: Computer Forencis Experiment 2000
- Information Directorate (AFRL) partnership with
Hypothesis: possible to determine the motives, intent,
targets, sophistication, identity and location of cyber
terrorists by deploying an integrated forensics analysis
Tools included commercial products and research
Papers to be Discussed (November 2-4, 2009)
Cyber Forensics: a Military Perspective
How to Reuse Knowledge about Forensic Investigations
2. Danilo Bruschi, Mattia Monga, Universit`a degli Studi di
3. John Lowry, BBN Systems: Adversary Modeling to Develop
Forensic Observables
4. Dr. Golden G. Richard III, University of New Orleans, New
Orleans, LA: Breaking the Performance Wall: The Case for
Distributed Digital Forensics