1 / 86

Information Systems Security

Information Systems Security. Telecommunications Domain #7. OSI Reference Model. Physical Datalink Network Transport Session Presentation Application. Routing. Dynamic RIP I RIP II OSPF BGP. Cabling Types - Coaxial. Copper wire insulated by braided metallic ground shield

ros
Download Presentation

Information Systems Security

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. Information Systems Security Telecommunications Domain #7

  2. OSI Reference Model • Physical • Datalink • Network • Transport • Session • Presentation • Application

  3. Routing • Dynamic • RIP I • RIP II • OSPF • BGP

  4. Cabling Types - Coaxial • Copper wire insulated by braided metallic ground shield • Less vulnerable to EMI • Two main types • 10BASE2 (Thinnet) (185 meters) • 10BASE5 (Thicknet) (500 meters) • Mainly used in one-way networks (TV) • Two-way networks required special equipment • Larger minimum arc radius than TP

  5. Cabling Type - TP • Copper-based • Two major types • UTP • Least secure • Susceptible to EMI, cross-talk, and eavesdropping • Less security than fiber or coaxial • Most commonly used today • STP • Extra outer foil shielding

  6. Cabling Type - Fiber • Data travels as photons • Higher speed, less attenuation, more secure • Expensive and harder to work with • Two major types • Multimode • Less expensive with slower speed • Single mode • Faster speeds available but more $ and delicate

  7. Signal Issues • Attenuation • Interference from environment • Cable runs are too long • Poor quality cable • Cross Talk • Signals radiate from a wire and interfere with other wires • Data corruption • More of a problem with UTP

  8. Transmission Types • Analog • Carrier signal used to move data • Signal works at different frequencies • Used in broadband networks • Digital • Discrete units of voltage • Moves data in binary representation • Cleaner signal compared to analog

  9. Encoding Techniques

  10. Synchronous or Asynchronous • Sync • Prior agreement of data TX rules • Sending system sends a clocking pulse • Stop and start bits are not required • T-lines & optical lines use synchronous • Asynchronous • Must use start/stop bits • Dial-up connections use asynchronous

  11. Broadband or Baseband • Baseband • TX media only uses one channel • Digital signaling • Used over TP or Coax • Broadband • Multiple channels • TXs more data at one time • Can use analog signaling • Used over coax or fiber (at 100Mbps or more) • Can carry video, audio, data, and images

  12. Plenum Cable • Polyvinyl chloride can give off dangerous chemicals if burned • Plenum rated cable is made of safe fluoropolymers • Should be used in dropped ceilings and raised floorings and other ventilation areas

  13. Number of Receivers • Unicast • One system communicates to one system • Multicast • One system communicates to many systems • Class D addresses dedicated to this • “Opt-in” method (webcasts, streaming video) • Broadcast • One system communicates to all systems • Destination address contains specific values

  14. Types of Networks • Local Area Network (LAN) • Limited geographical area • Ethernet and Token Ring • Metropolitan Area Network (MAN) • Covers a city or town • SONET, FDDI • Wide Area Network (WAN) • ATM, Frame Relay, X.25

  15. Network Terms • Internet • Network of networks providing a communication infrastructure • The web runs on top of this Internet infrastructure • Intranet • Employs Internet technology for internal use • HTTP, web browsers, TCP/IP

  16. Network Terms • Extranet • Intranet type of network that allows specific entities to communicate • Usually business partners and suppliers • B2B networks • Shared DMZ area or VPN over the Internet

  17. Network Configuration • DMZ • Network segment that is between the protected internal network and the external (non-trusted) network • Creates a buffer zone • Systems in DMZ will be the 1st to come under attack and must be properly fortified

  18. Physical Layer • Network Topologies • Physical connection of system and devices • Architectural layout of network • Choice determined by higher level technologies that will run on it • Types (Bus, Ring, Star, Mesh)

  19. BUS • Nodes are connected to a backbone through drops • Linear bus – one cable with no branches • Tree – network with branches • Easy to extend • Single node failure affects ALL participants • Cable is the single point of failure

  20. Ring • Interconnection of nodes in circle • Each node is dependent upon the physical connection of the upstream node • Data travels unidirectionally • One node failure CAN affect surrounding nodes • Used more in smaller networks

  21. Star • All computers are connected to central device • Central device is single point of failure • No node-to-node dependencies

  22. Mesh • Network using many paths between points • Provides transparent rerouting when links are down • High degree of fault tolerance • Partial Mesh – Not every link is redundant • Internet is an example • Full Mesh – All nodes have redundancy

  23. Media Access • Dictates how system will access the media • Frames packets with specific headers • Different media access technologies • CSMA • Token Ring • Polling • Protocols within the data link • SLIP, PPP, L2F, L2TP, FDDI, ISDN

  24. Carrier Sense Multiple Access • CSMA/CD (Collision Detection) • Monitors line to know when it is free • When cable not busy, data is sent • Used in Ethernet • CSMA/CA (Collision Avoidance) • Listens to determine is line is busy • Sends out a warning that message is coming • All other nodes go into waiting mode • Used in 802.11 WLANs

  25. Wireless Standards (802.x) • 802.11 – 2.4 GHz range at 1-2 Mbps • 802.11b – 2.4 GHz up to 11 Mbps • 802.11a – 5 GHz up to 54 Mbps • 802.11g – 2.4 GHz up to 54 Mbps • 802.11i – Security protocol (replace WEP) • 802.15 – Wireless PANs • 802.16 – Wireless MANs

  26. Access Points • Connects a wireless network to a wired network • Devices must authenticate to the AP before gaining access to the environment • AP works on a specific frequency that the wireless device must “tune itself” to

  27. Service Set ID (SSID) • WLANs can be logically separated by using subnet addresses • Wireless devices and APs use SSID when authenticating and associating • Should not be considered a security mechanism

  28. Authenticating to the AP • Station sends probe to all channels looking for the closest AP • AP will respond with the necessary information and a request for credentials • If WEP key is required, AP sends a challenge to the device and device encrypts with key and send it back • If no WEP key, could request SSID value and MAC value

  29. Wired Equivalent Protocol (WEP) • Protocol used to encrypt traffic for all IEEE wireless standards • Riddled with security flaws • Improper implementation of security mechanisms • No randomness (uses the same password) • No Automated Dynamic Key Refresh Method (DKRM), requires manual refresh

  30. More WEP Woes • Small initialization vector values • Uses a 24-bit value • Exhaust randomness is as little as 3 hours • Uses stream cipher (RC4) • No data integrity • Use XORs – flip a bit in ciphertext the corresponding bit in plaintext is flipped

  31. Wireless Application Protocol (WAP) • Requires a different protocol stack than TCP/IP • WAP allows wireless devices to access the Internet • Provides functions at each of the OSI layers similar to TCP/IP • Founded in 1997 by cell phone companies

  32. Wireless Transport Layer Security • Security layer of the WAP • Provides privacy, integrity, and authentication for WAP applications • Data encrypted with WTLS must be decrypted and reencrypted with SSL or TLS

  33. Common Attacks • Eavesdropping on traffic and spoofing • Erecting a rogue AP • Man-in-the-middle • Unauthorized modification of data • War driving • Cracking WEP • Birthday attacks • Weak key attacks (airsnort, WEPCrack)

  34. War Driving • Necessary Components • Antenna (omnidirectional is best) • Sniffers (TCPDump, Ethereal) • NetStumbler, AirSnort, or WEPCrack • NetStumbler finds APs and Logs • Network name • SSID • MAC • Channel ID • WEP (yes or no)

  35. Wireless Countermeasures • Enable WEP • Change default SSID and don’t broadcast • Implement additional authentication • Control the span of the radio waves • Place AP in DMZ • Implement VPN for wireless stations • Configure firewall for known MAC and IP

  36. TCP/IP Suite • TCP – connection oriented transport layer protocol that provides end-to-end reliability • IP – connectionless network layer protocol that provides the routing function • Includes other secondary protocols

  37. Port and Protocol Relations • Well known port numbers are 0-1023 • FTP is 20 and 21 • SMTP is 25 • SNMP is 161 • HTTP is 80 • Telnet is 23 • HTTPS is 443 • Source is usually a high dynamic number while destination is usually under 1024

  38. Address Resolution Protocol (ARP) • Maps the IP address to the MAC address • Data link understands MAC, not IP • Element in man-in-the middle attacks • Intruder spoofs its MAC address against the destination’s IP address into ARP cache • Countermeasures • Static ARP, active monitoring, and IDS to detect anomalies

  39. ARP Poisoning • Insert bogus IP to MAC addressing mapping in remote system • Misdirect traffic to attacker’s computer • Ideal scenario for man-in-the-middle attack

  40. Internet Control Message Protocol (ICMP) • Status and error messaging protocol • Ping is an example • Used by hackers for host enumeration • Redirects traffic by sending bogus ICMP messages to a router

  41. Simple Network Management Protocol (SNMP) • Master and agent model • Agents gather status information about network devices • Master polls agent and provides an overall view of network status • Runs on ports 161 and 162

  42. Simple Mail Transfer Protocol (SMTP) • Transmits mail between different mail servers • Security issue with mail servers • Improperly configured mail relay • Sendmail functions

  43. Other Protocols • FTP • TFTP • Telnet

  44. Repeater Device • Works at the physical layer • Extends a network • Helps with attenuation • No intelligence built in

  45. Hub Devices • Works at the physical layer • Connects several systems and devices • Also called multipoint repeater/concentrators • All data is broadcast • No intelligence

  46. Bridge Device • Functions at the data link layer • Extends a LAN by connecting similar or dissimilar LANs • Filtering capabilities • Uses the MAC address • Forwards broadcast data • Transparent – Ethernet • Source Routing – Token Ring

  47. Switch Device • Transfers connection from one circuit to another • Faster than bridges • Originally made decisions based on MAC • Major functionality takes place at Data Link Layer • Newer switches work at the Network layer and use IP addresses

  48. Virtual LAN (VLAN) • Logical containers used to group users, systems, and resources • Does not restrict administration based upon the physical location of device • Each VLAN has its own security policy • Used in switches • Can be static or dynamic

  49. Router Device • Works at the network layer • Can connect similar or dissimilar networks • Blocks broadcast • Uses routing tables • Bases decisions on IP addresses • Can work as a packet filtering firewall wit the use of Access Control Lists

More Related