Chao-Hsien Chu, Ph.D. College of Information Sciences and Technology The Pennsylvania State University University Park, PA Web Forensics & Tracing 8/24/06 Learning by Doing Theory  Practice

Objectives Understand the flow of electronic mail across a network Explain the difference between resident client programs and webmail Understand the difference between typical desktop data storage and server data storage Identify the components of headers Understand the flow of instant messaging across the network

Importance of as Evidence can be pivotal evidence in a case Due to its informal nature, it does not always represent corporate policy Many cases provide examples of the use of as evidence –Enron –Microsoft - Bill Gate –Knox vs. State of Indiana –Harley vs. McCoach –Nardinelli et al. vs. Chevron –Adelyn Lee vs. Oracle Corporation

Working with evidence typically used to corroborate or refute other testimony or evidence Can be used by prosecutors or defense parties Two standard methods to send and receive –Client/server applications –Webmail

Data Flow User has a client program such as Outlook or Eudora Client program is configured to work with one or more servers s sent by client reside on PC A larger machine runs the server program that communicates with the Internet, where it exchanges data with other servers

Sending User creates on her client User issues send command Client moves to Outbox Server acknowledges client and authenticates account Client sends to the server Server sends to destination server If the client cannot connect with the server, it keeps trying

Receiving User opens client and logs on User issues receive command Client contacts server Server acknowledges, authenticates, and contacts mail box for the account Mail downloaded to local computer Messages placed in Inbox to be read POP deletes messages from server; IMAP retains copy on server

Working with Resident Files Users are able to work offline with is stored locally, a great benefit for forensic analysts because the is readily available when the computer is seized Begin by identifying clients on system You can also search by file extensions of common clients

Working with ClientExtensionType of File AOL.abi.aim.arl.bag AOL6 organizer file Instant Message launch Organizer file Instant Messenger file Outlook Express.dbx.dgr. .eml OE mail database OE fax page OE mail message OE electronic mail Outlook.pab.pst.wab Personal address book Personal folder Windows address book (Continued)

Working with ClientExtensionType of File Lotus Notes.box.ncf.nsf Notes mailbox Notes internal clipboard Notes database Novell Groupwise.mlmSaved (using WP5.1 format) Eudora.mbxEudora message base

Popular Clients America Online (AOL) - users have a month to download or save before AOL deletes messages Outlook Express - installed by default with Windows Outlook - bundled with Microsoft Office Eudora - popular free client Lotus Notes - integrated client option for Lotus Domino server

Webmail Data Flow User opens a browser, logs in to the webmail interface Webmail server has already placed mail in Inbox User uses the compose function followed by the send function to create and send mail Web client communicates behind the scenes to the webmail server to send the message No s are stored on the local PC; the webmail provider houses all

Working with Webmail Entails a bit more effort to locate files Temporary files is a good place to start Useful keywords for webmail programs include: –Yahoo! mail: ShowLetter, ShowFolder Compose, “Yahoo! Mail” –Hotmail: HoTMail, hmhome, getmsg, doattach, compose –Gmail: mail[#]

Protocol POP3IMAPWebmail accessible from anywhere NoYes Remains stored on server No (unless included in a backup of server) YesYes, unless POP3 was used too Dependence on Internet ModerateVery strong Strong Special software required Yes No

Working with Mail Servers Some initial things to consider: –How many users are serviced? – retention policies of the company –Accessibility of the server

Working with Mail Servers Redundant array of independent disks (RAID) –RAID 0: Basic disk striping –RAID 1: Disk mirroring –RAID 3: Striping with parity –RAID 5: Striping with distributed parity –RAID 0+1 and 10 (1+0): Mirror of stripes and striped mirroring

Working with Mail Servers Harvesting data from RAID servers –Easiest way to obtain the data is over the network –Considerations: Time to obtain the data Physical configuration and space Production server downtime

Examining s for Evidence Understanding headers –The header records information about the sender, receiver, and servers it passes along the way –Most clients show the header in a short form that does not reveal IP addresses –Most programs have an option to show a long form that reveals complete details

Examining s for Evidence Most common parts of the header are logical addresses of senders and receivers Logical address is composed of two parts –The mailbox, which comes before sign –The domain or hostname that comes after sign The mailbox is generally the userid used to log in to the server The domain is the Internet location of the server that transmits the

Examining s for Evidence Reviewing headers can offer clues to true origins of the mail and the program used to send it Common header fields include: –Bcc –Cc –Content-Type –Date –From –Message-ID –Received –Subject –To –X-Priority

IP Address Registries African Network Information Asia Pacific Network Information American Registry for Internet Number Latin American and Caribbean Internet Addresses Registry Réseaux IP Européens Network Coordination Centre

Examining s for Evidence Understanding attachments –MIME standard allows for HTML and multimedia images in –Searching for base64 can find attachments in unallocated or slack space Anonymous r ers –Allow users to remove identifying IP data to maintain privacy –Stems from users citing the First Amendment and freedom of speech

Private IP Address Classifications IP Address RangeClassificationUse to Class A Local network use—not recognized on the Internet to Class B Local network use—not recognized on the Internet to Class C Local network use—not recognized on the Internet

Working with Instant Messaging Most widely used IM applications include: –Windows Messenger –Google Talk –AIM (AOL Instant Messenger) –ICQ (“I Seek You”) Instant Messenger Newer versions of IM clients and servers allow the logging of activity Can be more incriminating than

Taking the Initial Report GET THE HEADERS!!! Get as accurate a timeline as possible Timezones are important!! Be sure the original is not deleted Simply forwarding does not preserve the headers

Right Click

Tools for Tracing Nslookup –DOS Command Prompt – American Registry. Sam Spade: