1 / 50

Chao-Hsien Chu, Ph.D. College of Information Sciences and Technology

Web Forensics & E-mail Tracing. Chao-Hsien Chu, Ph.D. College of Information Sciences and Technology The Pennsylvania State University University Park, PA 16802 chu@ist.psu.edu. Theory  Practice. Learning by Doing. 8/24/06. Objectives.

ginata
Download Presentation

Chao-Hsien Chu, Ph.D. College of Information Sciences and Technology

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Web Forensics & E-mail Tracing Chao-Hsien Chu, Ph.D. College of Information Sciences and Technology The Pennsylvania State University University Park, PA 16802 chu@ist.psu.edu Theory  Practice Learning by Doing 8/24/06

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

  3. Importance of E-Mail as Evidence • E-mail 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 e-mail as evidence • Enron • Microsoft - Bill Gate • Knox vs. State of Indiana • Harley vs. McCoach • Nardinelli et al. vs. Chevron • Adelyn Lee vs. Oracle Corporation

  4. Working with E-Mail • E-mail 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 e-mail: • Client/server applications • Webmail

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

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

  7. Receiving E-Mail 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

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

  9. Working with E-Mail (Continued)

  10. Working with E-Mail

  11. Popular e-mail 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

  12. 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 e-mails are stored on the local PC; the webmail provider houses all e-mail

  13. 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[#]

  14. E-Mail Protocol

  15. Working with Mail Servers • Some initial things to consider: • How many users are serviced? • E-mail retention policies of the company • Accessibility of the e-mail server

  16. 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

  17. 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

  18. Examining E-Mails for Evidence • Understanding e-mail headers • The header records information about the sender, receiver, and servers it passes along the way • Most e-mail 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

  19. Examining E-Mails for Evidence • Most common parts of the e-mail header are logical addresses of senders and receivers • Logical address is composed of two parts • The mailbox, which comes before the @ sign • The domain or hostname that comes after the @ sign • The mailbox is generally the userid used to log in to the e-mail server • The domain is the Internet location of the server that transmits the e-mail

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

  21. 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

  22. Examining E-Mails for Evidence • Understanding e-mail attachments • MIME standard allows for HTML and multimedia images in e-mail • Searching for base64 can find attachments in unallocated or slack space • Anonymous remailers • Allow users to remove identifying IP data to maintain privacy • Stems from users citing the First Amendment and freedom of speech

  23. Private IP Address Classifications

  24. 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 e-mail

  25. Taking the Initial Report • GET THE HEADERS!!! • Get as accurate a timeline as possible • Timezones are important!! http://tycho.usno.navy.mil/tzonemap.html • Be sure the original e-mail is not deleted • Simply forwarding e-mail does not preserve the headers

  26. Right Click

  27. Tools for E-mail Tracing • Nslookup • DOS Command Prompt • www.infobear.com/nslookup.shtml • www.traceroute.org • http://www.whois.net/ • American Registry. http://www.arin.net/index.shtml • Sam Spade: www.samspade.org

More Related