Computer Crime & Intellectual Property Section NetworksNetworks andand thethe InternetInternet AA PrimerPrimer forfor ProsecutorsProsecutors andand InvestigatorsInvestigators Michael J. Stawasz Senior Counsel Computer Crime and Intellectual Property Section (CCIPS) Criminal Division, U.S. Department of Justice USDOJ CCIPS GettingGetting There…There… From networks to the Internet Locating a place on the Internet Applications that people use on the Internet 2 USDOJ CCIPS …to…to GetGet thethe EvidenceEvidence What evidence does Internet use create? Where is this evidence located? How do we gather this evidence? 3 USDOJ CCIPS GettingGetting There…There… From networks to the Internet Locating a place on the Internet Applications that let people use the Internet 4 USDOJ CCIPS WhatWhat isis aa network?network? 5 USDOJ CCIPS WhatWhat isis anan inter-network?inter-network? Node Router 6 USDOJ CCIPS Network WhatWhat IsIs thethe IInternet?nternet? 7 USDOJ CCIPS AA DecentralizedDecentralized NetworkNetwork No “center” No one is in charge No one knows exactly where all the components are located 8 USDOJ CCIPS HowHow dodo InternetInternet hostshosts exchangeexchange data?data? WEB PAGE MOVIE E-MAIL MESSAGE DATAPACKETS VOICE SOFTWARE 9 USDOJ CCIPS ExchangingExchanging DataData Information to be sent to another Internet host is divided into small DATA PACKETS The data packets are sent over the network to the receiving host The receiving host assembles the data packets into the complete communication 10 USDOJ CCIPS ExchangingExchanging DataData 11 USDOJ CCIPS InternetInternet ProtocolProtocol (IP)(IP) PacketsPackets SOURCE 172.31.208.99 ADDRESS 213.160.116.205 DESTINATION ADDRESS 0111001010101011 1011011000100101 0100... DATA BEING SENT 12 USDOJ CCIPS GettingGetting There…There… From networks to the Internet Locating a place on the Internet Applications that let people use the Internet 13 USDOJ CCIPS IPIP AddressesAddresses 213.160.116.205 14 USDOJ CCIPS AssigningAssigning IPIP AddressesAddresses Public Dynamic Private Static Blocks of IP addresses registered to Internet service providers (ISP) 15 USDOJ CCIPS AssigningAssigning IPIP AddressesAddresses INTERNETINTERNET Computer Modem Internet Service Provider 149.101.1.120 149.101.1.120 assigned to Harry at 2:30 PM 16 USDOJ CCIPS ISPISP LoginLogin RecordsRecords The ISP-equivalent of telephone company records Records each time a user logs in (or tries and fails) Logs show à Start time à Session duration à Account identifier à Assigned IP address 17 USDOJ CCIPS TheThe TracebackTraceback We know the IP address used by the suspect How do we find out who this person is? 149.101.1.120 → ???? 18 USDOJ CCIPS StepStep 1:1: WhatWhat ISPISP hashas thatthat address?address? Use the “IP whois” service to find out what ISP owned that IP address. 149.101.1.120 → 19 USDOJ CCIPS StepStep 2:2: WhatWhat useruser hadhad thatthat addressaddress atat thatthat time?time? Subpoena the ISP to find out who had that address Specify at least the address and the time and date with time zone. Subpoena + 20 USDOJ CCIPS AnotherAnother LocationLocation Method:Method: ProspectiveProspective EvidenceEvidence GatheringGathering We know that our suspect was at a site and believe he’ll return A pen/trap device installed at the Pen/Trap site’s server provides the suspect’s Order IP address when he returns INTERNET 21 USDOJ CCIPS AA Twist:Twist: TheThe NATNAT Several computers share one IP address Outside world sees the same address regardless of which computer communicates 10.232.33.10 10.232.33.9 NAT INTERNET 10.232.33.8 149.101.1.120 22 USDOJ CCIPS AnotherAnother Twist:Twist: TheThe ProxyProxy “Laundering” communications through someone else’s IP address Outside world sees only the proxy’s IP address PROXY 23 USDOJ CCIPS InfamousInfamous ProxiesProxies America Online’s proxy cache Proxy caches used by private companies Bots Anonymizers 24 USDOJ CCIPS DomainDomain NamesNames How humans handle IP addresses Every domain name has “whois” information à Owner, physical address, contact information à Almost always wrong if the domain name is registered by a criminal Assume nothing about geography thecommonwealth.org = 213.160.116.205 25 USDOJ CCIPS DomainDomain NameName QueriesQueries 213.160.116.205 Who is thecommonwealth.org? DOMAIN NAME SYSTEM ISP 26 USDOJ CCIPS GettingGetting There…There… From networks to the Internet Locating a place on the Internet Applications that let people use the Internet 27 USDOJ CCIPS HowHow PeoplePeople UseUse thethe InternetInternet WEB PAGE MOVIE E-MAIL MESSAGE DATAPACKETS VOICE SOFTWARE APPLICATIONS 28 USDOJ CCIPS InternetInternet UseUse ApplicationsApplications E-mail Web browser Peer-to-peer (P2P) Instant messaging (IM) Internet relay chat (IRC) File transfer protocol (FTP) 29 USDOJ CCIPS InternetInternet UseUse ApplicationsApplications E-mail Web browser Peer-to-peer (P2P) Instant messaging (IM) Internet relay chat (IRC) File transfer protocol (FTP) 30 USDOJ CCIPS E-MailE-Mail BasicsBasics E-mail travels from sender to recipient’s host, where it resides on a MAIL SERVER until the recipient retrieves it RECIPIENT’S SENDER’S ISP ISP INTERNETINTERNET 31 USDOJ CCIPS EvidenceEvidence ofof PastPast ActivityActivity –– Content Content Copies of a previously sent e-mail message may be stored on the à sender’s system à recipient’s mail server (even after addressee has read it) à recipient’s own machine RECIPIENT’S SENDER’S ISP ISP INTERNETINTERNET 32 USDOJ CCIPS EvidenceEvidence ofof PastPast ActivityActivity –– Traffic Traffic DataData A record of the e-mail transmission (date, time, source, destination) usually resides in the MAIL LOGS of the à sender’s system à recipient’s mail server RECIPIENT’S SENDER’S ISP ISP INTERNETINTERNET 33 USDOJ CCIPS ProspectiveProspective EvidenceEvidence –– Content Content Interception, “wiretap” Creates a “cloned” account SUBJECT’S SUBJECT’S ISP COMPUTER INTERNETINTERNET LAW ENFORCEMENT Wiretap Order COMPUTER 34 USDOJ CCIPS ProspectiveProspective EvidenceEvidence –– Traffic Traffic DataData Install a pen/trap at user’s ISP to find out the e-mail addresses the user corresponds with SUBJECT’S SUBJECT’S ISP COMPUTER INTERNETINTERNET Pen/Trap Order LAW ENFORCEMENT 35 USDOJ CCIPS InternetInternet UseUse ApplicationsApplications E-mail Web browser Peer-to-peer (P2P) Instant messaging (IM) Internet relay chat (IRC) File transfer protocol (FTP) 36 USDOJ CCIPS WhatWhat isis aa webweb site?site? Three components à Domain name (or other address) à A web hosting server à Files sitting on the web hosting server eac.inteac.int 37 USDOJ CCIPS AA Twist:Twist: VirtualVirtual HostingHosting One server hosts hundreds of web sites All web sites share a single IP address Think carefully before you seize or search an entire server 38 USDOJ CCIPS WebWeb AddressesAddresses Uniform Resource Locators (URL) http://www.thecommonwealth.org/Internal/163207/151537/148540/podcast/ Computer File http://www.eac.int/index.php/secretariat.html Computer File 39 USDOJ CCIPS BrowsingBrowsing thethe Web:Web: Client-ServerClient-Server InteractionInteraction User types a URL or clicks on link User’s computer looks up IP address www.eac.int 41.220.130.18 DOMAIN NAME INTERNET SYSTEM USER ISP 40 USDOJ CCIPS BrowsingBrowsing thethe Web:Web: Client-ServerClient-Server InteractionInteraction User’s CLIENT PROGRAM sends a request to the WEB SERVER at the specified IP address The web server transmits a copy of the requested document (the web page) to the user’s computer 41.220.130.18 INTERNET USER ISP WEB SERVER 41 USDOJ CCIPS BrowsingBrowsing thethe Web:Web: Client-ServerClient-Server InteractionInteraction The client program displays the transmitted document on the user’s screen 42 USDOJ CCIPS EvidenceEvidence ofof WebWeb Query:Query: OnOn User’sUser’s ComputerComputer Cache directory à Copies of recently viewed web pages History file à List of recently visited pages INTERNET USER ISP WEB SERVER 43 USDOJ CCIPS EvidenceEvidence ofof WebWeb Query:Query: OnOn WebWeb ServerServer Detailed logs of each request for any page à Date, time à Number of bytes à IP address of the system that requested the data INTERNET USER ISP WEB SERVER 44 USDOJ CCIPS ExampleExample WebWeb ServerServer LogLog 10.143.28.198 - - [11/Feb/2007:22:45:17 -0500] "GET /tank.htm HTTP/1.1" 401 - "-" "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.1) Gecko/20061204 Firefox/2.0.0.1“ 10.143.28.198 - visitor [11/Feb/2007:22:45:23 -0500] "GET /images/lolita.png" 200 3788 "http://www.eruditorium.org/" "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.1) Gecko/20061204 Firefox/2.0.0.1“ 10.143.28.198 - visitor [11/Feb/2007:22:46:11 -0500] "POST /dynamic/ HTTP/1.1" 200 413 "http://www.eruditorium.org/" "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.1) Gecko/20061204 Firefox/2.0.0.1" 45 USDOJ CCIPS SeeSee aa theme?theme? To do anything on the Internet, a computer communicates with another computer using an IP address Hopefully, that other computer will log what the suspect has done With that in mind… 46 USDOJ CCIPS OtherOther InternetInternet UseUse ApplicationsApplications Peer-to-peer (P2P) Instant messaging (IM) Internet relay chat (IRC) File transfer protocol (FTP) 47 USDOJ CCIPS InIn Closing…Closing… The Internet is a packet-switched network Systems keep many records about their interactions with the rest of the network Those records often help us locate and identify criminal actors, or at least to bolster the other evidence against them 48 USDOJ CCIPS Michael J. Stawasz Senior Counsel, CCIPS [email protected] (202) 514-1026 49.