Digital inVESTigations

Forensics and Audit Trails

About Me

Marc HullegieMarc Hullegie is founder and CEO of Vest Information Security and is widely experienced in the information security business in all types of areas: Security Architecture and Infrastructure, Security Audits and Testing, Security Management, Awareness and Digital Forensics. He presents lectures at (international) conferences and is looking forward to share experiences at the OWASP Benelux days 2012 with you.

Kees MastwijkKees Mastwijk is a security consultant working with Vest, acting as Security Auditor, Awareness Program leader and security Manager. He has a long (and ongoing) experience history in Digital Forensic Research.

TALK OUTLINEBasics

Principles

Audit Trails

Timeline Analysis

Challenges BIG DataSolid State DrivesCloud ComputingChanging forensic landscape

Trends TriageVisualization

And then What ?

INVESTIGATION BASICS

Why will people commit fraud / crime /’misbehavior’ / ….

Fraud Triangle:• Opportunity – One has to be able to commit fraud• Motive – There is a ‘drive’ to commit fraud• Rationalization – Actions will be justified

INVESTIGATION BASICS

Understanding of the Fraud Triangle can be helpful for:• Formulating the investigation charter• Creating scenarios• Applicable for fraud & forensic investigations

and securitytesting

TYPES OF DIGITAL INVESTIGATIONS(due to the nature of the fraud / crime ..)

• Against computersystems, e.g hacking, spam, • Where computersystems are used to commit

fraud, stalking, harrassment

CHARACTERISTICS OF GOOD EVIDENCE

• Intact/integer• Relevant• Reproducable

REQUIRED SKILLS AND KNOWLEDGE

- Technical skills Understand what kind of evidence you are looking for,

&- Investigative skills

Being able to understand the value of the evidence in the case and translate highly technical findings to easy to understand report, being able to spot abnormalities

- While maintaining the ‘chain of custody’

KNOW YOUR STUFF !

BASICS

Basic steps in a digital forensic investigation

• Preparation• Acquisition of Evidence• Duplication• Extraction• Analysis• Reporting

PREPARATION

• Investigation Charter• Determine the scope and preconditions of the investigation• Determine potential locations of relevant evidence by means of type of

investigation:- Network- Data carriers like hard disk drives, smartphones, USB drives

etc- Memory- Etc.. Etc..

• Expectation Management / (Communication) • Create investigation Log (and maintain during the proces)

ACQUISITION & PRESERVATION

• NEVER conduct an investigation on original material• Acquire potential evidence following forensically sound

procedures, tools and hardware• Use write-protected hardware and software that

ensures the integrity of the copy• Duplicate the acquired evidence files to a secured back-

up location• Note System config settings, especially time related

EXTRACTION

• Compound files (Zip/rar/certain e-mail archives) may need to be extracted in order to be able to search the files.

• Transform data into usable investigation objects• Disk images contain potential ‘hidden’ evidence

in file slack, unallocated clusters etc

UNALLOCATED CLUSTERS

CARVING UNALLOCATED CLUSTERS

ANALYSIS

• Select tooling to conduct analysis• Many tools available, specific for each type of

investigation• Cross check and verify your findings. Do not rely

on the results of one tool• Keep in mind the questions to be answered in

the investigation or you will get lost

REPORTING• Translate findings into a readable report• Be transparent in describing your investigative

process• Answer the ‘W’ and ‘H’ questions: Who did

What, When, Where, When, Why and How• Do not jump to conclusions! Be aware of

tunnel visioning

CHALLENGES IN DIGITAL FORENSICS

• BIG data changes the way investigations will be conducted• Diversity of equipment used in today’s communications• Solid State Disks (SSD) reduces the likelihood of retrieving

good evidence (if deleted previously)• Unclear where your data is: e.g. Cloud Computing

changes potential source locations• Virtual Desktop Infrastructures• Compliancy rules limiting access to public records

TRENDS IN DIGITAL FORENSICS – TRIAGE

• Screening of potential evidence instead of creating a full disk image first, to efficiently and cost effective conduct digital investigations. Average storage in a system has increased substantially.

TRENDS IN DIGITAL FORENSICS – TRIAGE - CONT

Previewing and searching potential evidence saves a lot of time and storage.If a triaged systems contain sources of evidence, create a full disk image.

TRENDS IN DIGITAL FORENSICS – VISUALIZATION

• Visualize BIG data to correlate events, relationships, systems.

• Profiling applications

AUDIT TRAILS

In a digital forensic context:‘Chronological presentation of actions and events extracted from user or system generated information’

SYSTEM GENERATED EVIDENCE

Users have little understanding and awareness of presence of this kind of evidence!

Some examples• NTUSER.DAT• Webserver logs• Index.dat files• Printspooler logs• E-mail headers• Registry files• Temp/tmp folders• Etc..

USER CREATED EVIDENCESome examples:• Pictures• (Open) Office documents• Internet history• Chat services • E-mails

OTHER POTENTIAL EVIDENCE

Call registersAttendance registersSurveillance video’sEtc..

Note: Mind regulations for privacy, proportionality and subsidiarity

AUDIT TRAILS COMBINED

Combining system generated, user generated along with additional information creates a complete audit trailInterrelate and correlate, minding proper synchronization and unique identifiers (don’t assume) (user williamsj does not have to be John Williams)

FORENSIC READINESS

• Be prepared for incidents, they WILL happen • Compliancy• Prevention• Early Warnings• Limit “damage”• Reduction of investigation cost/time• Effectiveness in sanction (HR/Legal/IT)

CASE

‘Did speaker participate in OWASP Belenux 2012 conference’

CASE – CONT

Potential evidence:• Laptop speaker• Network/server logs• Smartphone• Call registers

CASE – CONT

Hard disk evidence• Keyword search• System file analysis

CASE – CONTHits• Unallocated clusters (system generated)

CASE – CONTHits• Pagefile (System generated)

CASE – CONTHits• NTUSER.DAT

CASE – CONTHits• Network data – firewall logs

CASE – CONTHits• E-mailmessages• Message tracking logs• Etc etc

HOW CAN WEB DEVELOPERS HELP SUPPORT FORENSIC READINESS

• Webserver : Logs• Application server/ Middleware: Logs• Database server: Logs, system tables, memory

• Do not limit logfiles: verbose, and no overwrites

HOW CAN WEB DEVELOPERS HELP SUPPORT FORENSIC READINESS

• Applications:

What have YOU instructed the application to log / record ?

HOW CAN WEB DEVELOPERS HELP SUPPORT FORENSIC READINESS• The application “Knows and Sees” a lot !• CAPTURE THAT DATA:• Facilitate detailed logging for the purpose of audit trails:

Who - e.g. UseraccountWhat - (sequence of) ActivityWhen - Date/time stampsWhere - IP-address, geo info, endpoint characteristicsHow - Application navigation behavior

As much and detailed as possible ! Look across bridges, as far as you can see to both ends.

HOW CAN WEB DEVELOPERS HELP SUPPORT FORENSIC READINESS

• Where ?– (Additional) Log files– (system) Event log– Database !

• Mind: – Location and size– Access, Authorization …– Performance

• Forensic principals to be included in your design !

HOW CAN WEB DEVELOPERS HELP SUPPORT FORENSIC READINESS – CONT

• Add monitoring, triggering mechanisms to your (forensic) logging to enhance the traceability with early warning and even prevention advantages.

• It might also support your regular system debugging ;-)

HOW CAN WEB DEVELOPERS HELP SUPPORT FORENSIC READINESS

• Non-repudiation:Perform security tests so that fraudulent people cannot dispute their acts and the operation of your application.

(They will tell your application environment sucks!) Proof they’re wrong !

HOW CAN WEB DEVELOPERS HELP SUPPORT FORENSIC READINESS - CONT

• And don’t forget the traditional forensic sources:

• Not only application logs contain relevant information

• Consider logs of servers, network peripherals, workstations, syslogs

CONCLUSION

• All activity as shown on screen has potential to be recovered

• New technologies change the forensic landscape as well

• Be prepared for incidents and know how to handle while preserving potential evidence

• Be Forensic Ready! Be pro-active !

And then what ?

• Do not forget about “traditional” forensics• Adjust NOW to the changing landscape !• OWASP has a Forensic project opened in Aug• Let’s ALL contribute:

– We will ALL provide our knowledge and questions– List of tools– Facts about current forensic techniques (detailed techstuff)– Your environments and challenges– Compose a Forensics Ready (Secure) Application framework– Create new tools ?

Thank you

For any intermediate questions and suggestions:

– marc@vest.nl (Marc Hullegie)– kees@vest.nl (Kees Mastwijk)

www.vest.nl

See you all at the “OWASP Forensic Guide Project”http://owasp.org/index.php/owasp_forensic_guide_project