Transcript Document
Computer Security Workshop Module 1 – Footprinting / Packet Sniffing Footprinting Definition: the gathering of information about a potential system or network a.k.a. fingerprinting Attacker’s point of view Identify potential target systems Identify which types of attacks may be useful on target systems Defender’s point of view Know available tools May be able to tell if system is being footprinted, be more prepared for possible attack Vulnerability analysis: know what information you’re giving away, what weaknesses you have Information to Gather System (Local or Remote) IP Address, Name and Domain Operating System Type (Windows, Linux, Solaris, Mac) Version (98/NT/2000/2003/XP/Vista/7, Redhat, Fedora, SuSe, Ubuntu, OS X) Usernames (and their passwords) File structure Open Ports (what services/programs are running on the system) Information to Gather (2) Networks / Enterprises System information for all hosts Network topology Gateways Firewalls Overall topology Network traffic information Specialized servers Web, Database, FTP, Email, etc. Defender Perspective Identify information you’re giving away Identify weaknesses in systems/network Know when systems/network is being probed Identify source of probe Develop awareness of threat Construct audit trail of activity Tools - Linux Some basic Linux tools - lower level utilities Local System hostname ifconfig who, last Remote Systems ping traceroute nslookup, dig whois arp, netstat (also local system) Other tools lsof Tools – Linux (2) Other utilities wireshark (packet sniffing) nmap (port scanning) - more later Ubuntu Linux Go to System / Administration / Network Tools – get interface to collection of tools: ping, netstat, traceroute, port scan, nslookup, finger, whois Tools - Windows Windows Sam Spade (collected network tools) Wireshark (packet sniffer) Command line tools ipconfig Many others… hostname Determine host name of current system Usage: hostname E.g. hostname localhost.localdomain E.g. hostname mobile.cs.uwec.edu // default ifconfig Configure network interface Tells current IP numbers for host system Usage: ifconfig E.g. ifconfig // command alone: display status eth0 Link encap: Ethernet HWaddr 00:0C:29:CD:F6:D3 inet addr: 192.168.172.128 . . . lo Link encap: Local Loopback inet addr: 127.0.0.1 ... who Basic tool to show users on current system Useful for identifying unusual activity (e.g. activity by newly created accounts or inactive accounts) Usage: who E.g. who root tty1 Jan 9 12:46 paul tty2 Jan 9 12:52 last Show last N users on system Default: since last cycling of file -N: last N lines Useful for identifying unusual activity in recent past Usage: last [-n] E.g. last -3 wagnerpj pts/1 flinstf pts/0 rubbleb pts/0 137.28.253.254 Sat Feb 5 15:40 still logged in 137.28.191.74 Sat Feb 5 15:38 still logged in c48.someu.edu Sat Feb 5 14:38 - 15:25 (00:46) ping Potential Uses Is system online? Through response Gather name information Through DNS Tentatively Identify operating system Based on TTL (packet Time To Live) on each packet line TTL = number of hops allowed to get to system 64 is Linux default, 128 is Windows default (but can be changed!) Notes Uses ICMP packets Often blocked on many hosts; more useful within network Usage: ping system E.g. ping ftp.redhat.com E.g. ping localhost traceroute Potential Uses Determine physical location of machine Gather network information (gateway, other internal systems) Find system that’s dropping your packets – evidence of a firewall Notes Can use UDP or ICMP packets Results often limited by firewalls Several GUI-based traceroute utilities available Usage: traceroute system E.g. traceroute cs.umn.edu traceroute example - blocked [wagnerpj@data ~]$ traceroute cs.umn.edu traceroute to cs.umn.edu (128.101.34.202), 30 hops max, 38 byte packets 1 137.28.109.2 (137.28.109.2) 0.247 ms 0.220 ms 0.208 ms 2 v101.networking.cns.uwec.edu (137.28.9.1) 0.245 ms 0.229 ms 0.220 ms 3 uweauclairehub2-ge50.core.wiscnet.net (216.56.90.1) 1.315 ms 1.194 ms 1.343 ms 4 *** <ctrl-c> [wagnerpj@data ~]$ traceroute example - success H:\>tracert www.google.com Tracing route to www.google.akadns.net [64.233.167.99] over a maximum of 30 hops: 1 2 3 4 5 6 7 8 9 <1 ms <1 ms <1 ms v61.networking.cns.uwec.edu [137.28.61.1] 4 ms 6 ms 3 ms UWEauClaireHub2-ge50.core.wiscnet.net [216.56.90.1] 2 ms 1 ms 2 ms r-uweauclaire-isp-gig2-0.wiscnet.net [140.189.8.141] 17 ms 17 ms 17 ms chi-edge-08.inet.qwest.net [65.113.85.5] 18 ms 16 ms 18 ms chi-core-02.inet.qwest.net [205.171.20.113] 17 ms 18 ms 19 ms cer-core-01.inet.qwest.net [205.171.205.34] 18 ms 19 ms 21 ms chp-brdr-01.inet.qwest.net [205.171.139.146] 18 ms 17 ms 18 ms P11-0.CHICR2.Chicago.opentransit.net [193.251.129.113] 15 ms 16 ms 16 ms Google-EU-Customers-2.GW.opentransit.net [193.251.249.30] 10 16 ms 16 ms 18 ms 216.239.46.10 11 21 ms 19 ms 17 ms 64.233.175.30 12 18 ms 16 ms 16 ms 64.233.167.99 Trace complete. Visual Traceroute Example whois Potential Uses Queries nicname/whois servers for Internet registration information Can gather contacts, names, geographic information, servers, … - useful for social engineering attacks Notes Usage: whois domain e.g. whois netcom.com whois example - basic Domain Name: UWEC.EDU Registrant: University of Wisconsin - Eau Claire 105 Garfield Avenue Eau Claire, WI 54702-4004 UNITED STATES Contacts: Administrative Contact: Computing and Networking Services 105 Garfield Ave Eau Claire, WI 54701 UNITED STATES (715) 836-5711 [email protected] Name Servers: TOMATO.UWEC.EDU LETTUCE.UWEC.EDU BACON.UWEC.EDU 137.28.1.17 137.28.1.18 137.28.5.194 whois example - wildcards whois uw%.edu Your search has matched multiple domains. Below are the domains you matched (up to 100). For specific information on one of these domains, please search on that domain. UW.EDU UWA.EDU UWB.EDU UWC.EDU UWEC.EDU UWEST.EDU UWEX.EDU …. nslookup Potential Uses Query internet name servers Find name for IP address, and vice versa Notes Now deprecated – generally use dig Sometimes useful when dig fails Usage nslookup xxxxxxx // name or IP addr. E.g. nslookup data.cs.uwec.edu E.g. dig data.cs.uwec.edu dig Potential Uses Domain Name Service (DNS) lookup utility Associate name with IP address and vice versa Notes Many command options General usage: dig <somehost> E.g. dig data.cs.uwec.edu E.g. dig 137.28.109.33 arp Tracks addresses, interfaces accessed by system Possible uses Find systems that your system has recently talked to Notes arp arp –n // display names // display numeric addresses netstat Shows connections, routing information, statistics Possible uses find systems that your system has recently talked to, find recently used ports Notes Many flags netstat netstat –s netstat – r netstat – p netstat – l // open sockets, etc. // summary statistics // routing tables // programs // listening sockets lsof Lists open files on your system Useful to see what processes are working with what files, possibly identify tampering Usage: lsof Windows Tools Sam Spade “swiss army knife” of footprinting Has most of the Linux tools Plus other functionality Usage Start application Fill in name or IP address Choose option desired in menus Packet Sniffers Definition: Hardware or software that can display network traffic packet information Usage Network traffic analysis Example packet sniffers tcpdump (command line, Linux) wireshark (GUI interface, Linux, Windows – open source) others… Limitations – Packet Sniffing Packet sniffers only catch what they can see Users attached to hub – can see everything Users attached to switch – only see own traffic Wireless – wireless access point is like hub Need to be able to put your network interface card (NIC) in “promiscuous” mode to be able to process all traffic, not just traffic for/from itself NIC must support Need privilege (e.g. root in Linux) OSI Network Protocol Layer 7 – Application (incl. app. content) Layer 6 – Presentation Layer 5 – Session Layer 4 – Transport (incl. protocol, port) Layer 3 – Network (incl. source, dest) Layer 2 – Data Link Layer 1 – Physical wireshark Created as tool to examine network problems in 1997 Various contributors added pieces; released 1998 Name change (2007): ethereal -> wireshark Works with other packet filter formats Information http://www.wireshark.org Demonstration Using wireshark Ubuntu – Applications / Internet / Wireshark (as root) Enter your administrative account pw: user Capture/Interfaces/eth0:, Start Capture window shows accumulated totals for different types of packets Stop – packets now displayed Top window – packet summary Can sort by column – source, destination, protocol are useful Middle window – packet breakdown Click on + icons for detail at each packet level Bottom window – packet content Wireshark capture analysis Can save a session to a capture file Can reopen file later for further analysis Open capture file Ubuntu: /home/user/Support/MOBILEcapture.cap W2K3: C:\Support\MOBILEcapture.cap Identify and follow different TCP streams Select TCP packet, Analyze/Follow TCP Stream MOBILEcapture.cap has http, https, ftp, ssh streams Any interesting information out there? HINT: follow stream on an ftp packet Related Tool Hunt TCP sniffer Watch and reset connections Hijack sessions Spoof MAC address Spoof DNS name Related Tool EtherPEG – image capture on network http://www.etherpeg.com Summary Basic tools can generate much information Remember principle of accumulating information Attacker will build on smaller pieces to get bigger pieces Message to defenders: don’t give away any information if you can avoid it