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Intrusion Detection

Intrusion Detection. Outline. What is it? What types are there? Network based Host based Stack based Benefits of each Example Implementations Difference between active and passive detection HoneyPots. Intrusion Detection System (IDS). Detects malicious activity in computer systems

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Intrusion Detection

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  1. Intrusion Detection

  2. Outline • What is it? • What types are there? • Network based • Host based • Stack based • Benefits of each • Example Implementations • Difference between active and passive detection • HoneyPots

  3. Intrusion Detection System (IDS) • Detects malicious activity in computer systems • Identifies and stops attacks in progress • Conducts forensic analysis once attack is over

  4. The Value of IDS • Monitors network resources to detect intrusions and attacks that were not stopped by preventative techniques (firewalls, packet-filtering routers, proxy servers) • Expands available options to manage risk from threats and vulnerabilities

  5. Negatives and Positives • IDS must correctly identify intrusions and attacks • True positives • True negatives • False positives • Benign activity reported as malicious • False negatives • IDS missed an attack

  6. Dealing with False Results • False positives • Reduce number using the tuning process • False negatives • Obtain more coverage by using a combination of network-based and host-based IDS • Deploy NICS at multiple strategic locations in the network

  7. Types of IDS • Network-based (NIDS) • Monitors network traffic • Provides early warning system for attacks • Host-based (HIDS) • Monitors activity on host machine • Able to stop compromises while they are in progress

  8. Network-based IDS • Uses a dedicated platform for purpose of monitoring network activity • Analyzes all passing traffic • Sensors have two network connections • One operates in promiscuous mode to sniff passing traffic • An administrative NIC sends data such as alerts to a centralized management system • Most commonly employed form of IDS

  9. NIDS Interfaces NIDS Management Console no IP Address Data Link Data Flow

  10. NIDS Architecture • Place IDS sensors strategically to defend most valuable assets • Typical locations of IDS sensors • Just inside the firewall • On the DMZ • On the server farm segment • On network segments connecting mainframe or midrange hosts

  11. Connecting the Monitoring Interface • Using Switch Port Analyzer (SPAN) configurations, or similar switch features • Using hubs in conjunction with switches • Using taps in conjunction with switches

  12. SPAN • May be built into configurable switches (high end) • Allows traffic sent or received in one interface to be copied to another monitoring interface • Typically used for sniffers or NIDS sensors

  13. How SPAN Works Duplicated Traffic IDS Monitored Host Switch SPAN Port Monitored Port Data Link

  14. Monitor Network Segment Duplicated Traffic IDS Switch Data Link Monitored Hosts

  15. Limitations of SPAN • Traffic between hosts on the same segment is not monitored; only traffic leaving the segment crosses the monitored link • Switch may offer limited number of SPAN ports or none at all

  16. Hub • Device for creating LANs that forward every packet received to every host on the LAN • Allows only a single port to be monitored

  17. Using a Hub in a Switched Infrastructure Data Link Switch Switch IDS Monitored Host Hub

  18. Tap • Fault-tolerant hub-like device used inline to provide IDS monitoring in switched network infrastructures

  19. Using a Tap IDS Monitored Host Tap Tap acts like a 3 way hub where monitoring port is read only Monitoring Port Data Link

  20. Typical 10/100 8 port Tap Loss of power has no effect on traffic NetOptics Networktaps.com

  21. NIDS Signature Types • Signature-based IDS • Port signature • Header signatures

  22. Network IDS Reactions • TCP resets • IP session logging • Shunning or blocking

  23. Strengths of NIDS • Cost of Ownership • Lower because IDS is shared • Packet Analysis • Can look at all network traffic • Evidence Removal • Packets are captured in a separate machine • Real-Time Detection and Response • Can detect (and block) DDoS attacks • Operating System Independence

  24. Host-based IDS • Primarily used to protect only critical servers • Software agent resides on the protected system • Detects intrusions by analyzing logs of operating systems and applications, resource utilization, and other system activity • Use of resources can have impact on system performance

  25. HIDS Method of Operation • Auditing logs (system logs, event logs, security logs, syslog) • Monitoring file checksums to identify changes • Elementary network-based signature techniques including port activity • Intercepting and evaluating requests by applications for system resources before they are processed • Monitoring of system processes for suspicious activity

  26. HIDS Software • Host wrappers • Inexpensive and deployable on all machines • Do not provide in-depth, active monitoring measures of agent-based HIDS products • Agent-based software • More suited for single purpose servers

  27. HIDS Active Monitoring Capabilities • Log the event • Alert the administrator • Terminate the user login • Disable the user account

  28. Advantages of Host-based IDS • Verifies success or failure of attack by reviewing HIDS log entries • Monitors use and system specific activities; useful in forensic analysis of the attack • Can monitor network encrypted traffic • Near real-time detection and response • Analysis is log based, but good design mitigates much of the delay. • Can focus on key system components • No additional Hardware

  29. Stack based IDS • IDS is integrated with TCP/IP protocol stack • Allows system to provide real-time analysis and response • Intended to have low enough overhead so that each system can have its own IDS

  30. Passive Detection Systems • Can take passive action (logging and alerting) when an attack is identified • Cannot take active actions to stop an attack in progress

  31. Active Detection Systems • Have logging, alerting, and recording features of passive IDS, with additional ability to take action against offending traffic • Options • IDS shunning or blocking • TCP reset • Used in networks where IDS administrator has carefully tuned the sensor’s behavior to minimize number of false positive alarms

  32. Signature-based andAnomaly-based IDS • Signature detections • Also know as misuse detection • IDS analyzes information it gathers and compares it to a database of known attacks, which are identified by their individual signatures • Anomaly detection • Baseline is defined to describe normal state of network or host • Any activity outside baseline is considered to be an attack

  33. Intrusion Detection Products • Aladdin Knowledge Systems • Entercept Security Technologies • Cisco Systems, Inc. • Computer Associates International Inc. • CyberSafe Corp. • Cylant Technology • Enterasys Networks Inc. • Internet Security Systems Inc. • Intrusion.com Inc. family of IDS products

  34. Intrusion Detection Products (cont.) • NFR Security • Network-1 Security Solutions • Raytheon Co. • Recourse Technologies • Sanctum Inc. • Snort • Sourcefire, Inc. • Symantec Corp. • TripWire Inc.

  35. Honeypots • False systems that lure intruders and gather information on methods and techniques they use to penetrate networks—by purposely becoming victims of their attacks • Simulate unsecured network services • Make forensic process easy for investigators

  36. Honeypot Architecture Honeypot Data Link Switch Router Servers

  37. Commercial Honeypots • KFSensor • www.keyfocus.net/kfsensor • NetBait • www2.netbaitinc.com:5080 • Specter • www.specter.com • Decoy Server • www.symantec.com

  38. Open Source Honeypots Argos www.few.vu.nl/argos HoneyNet Project http://www.honeynet.org Honeyd www.honeyd.org The Deception Toolkit http://all.net/dtk/download.html cs490ns - cotter 38

  39. Honeypot Deployment • Goal • Gather information on hacker techniques, methodology, and tools • Options • Conduct research into hacker methods • Detect attacker inside organization’s network perimeter

  40. Honeypot Design • Must attract, and avoid tipping off, the attacker • Must not become a staging ground for attacking other hosts inside or outside the firewall

  41. Honeypots, Ethics, and the Law • Nothing wrong with deceiving an attacker into thinking that he/she is penetrating an actual host • Honeypot does not convince one to attack it; it merely appears to be a vulnerable target • Doubtful that honeypots could be used as evidence in court

  42. References • Security+ Guide to Network Security Fundamentals • Campbell, Calvert, Boswell – Course Technology, 2003 • HowTo Guide for IDS • http://www.snort.org/docs/iss-placement.pdf

  43. Summary • What is Intrusion Detection? • What types are there? • Network based • Host based • Stack based • Benefits of each • Example Implementations • Difference between active and passive detection • HoneyPots

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