Agenda What is IDS Why do I need IDS, I have a firewall? Types of IDS IDS Techniques Common ID Framework Issues in IDS Popular IDS Demo References Q&A
What is IDS A system that detects break-ins or misuse of a system in network. In short, its ‘burglar alarm’ for the network. An IDS can detect network scans, DoS, unauthorized attempt to connect to services in the network, improper activity etc..
Why do I need IDS, I have a firewall? Today’s security infrastructure include firewalls, virus scanners, authentication systems, VPN etc.. Given their role, these are prime targets and being managed by humans, they are error prone. Failure of one of these tools will jeopardize the security!.
Why do I need IDS, I have a firewall? – Contd.. Firewall is just not enough. Not all traffic go through them. Firewall does not protect against application level weaknesses and are subject to attack themselves.
Where should IDS go? Depends primarily on the network setup In a DMZ area immediately inside firewall. Important locations in network On a service host (like a webserver)
Types of IDS Host Based Collect and analyze data that originate from a host (e.g., web server) Network Based Collect and analyze packets that travel over network Stack Based (recent) Integrated into TCP/IP stack, so that the malicious packets are caught even before packets reach application
IDS Techniques Anomaly Detection Establish a baseline pattern and generates an alert when a flow of traffic deviates from baseline pattern. Misuse Detection (or) Signature Detection Generates an alert when a known intrusion matches existing signatures. Predict and Detect subsequent similar attempts. Target Monitoring Corrective control designed to uncover unauthorized action (file modification) after it occurs. Stealth Probes Checks for methodical attacks over a prolonged period of time. Discover correlating attacks.
Common ID Framework
Issues in IDS Large number of ‘false positives’. Very difficult to configure the security rules. Continuous update of signature database is must. NIDS is unreliable on high-speed and switched networks.
Popular IDS Tools Snort Cisco IDS RealSecure, by Internet Security Systems Dragon, by Enterasys NFR, by Flight Recorder (also available in a free research version) Tripwire, by the Tripwire Open Source team Tcpwrappers, by Wietse Venema PortSentry, by Psionic Technologies AIDE (Advanced Intrusion Detection Environment)
Demo Snort – is a light weight open source NIDS, capable of performing real time traffic analysis and packet logging. Snort works in various modes: sniffer mode (acts as protocol analyzer) packet-logger mode NIDS mode.
Network Topology supernova ( ) milkyway ( ) trudy ( ) SNORT Web server FTP server Internal Node The Intruder
References Book: Intrusion detection system with snort by Jack koziol Snort IDS (www.snort.org)www.snort.org Intrusion Detection Systems (www.certiguide.com/secplus/cg_sp_34IntrustionDetectionSystem.htm) An introduction to IDS (http://www.securityfocus.com/infocus/1520) Intrusion Detection FAQ: Why is intrusion detection required in today’s computing environment? (http://www.sans.org/resources/idfaq/id_required.php?http://www.sans.org/resources/idfaq/id_required.php IDS, what is it and why do we need it? (http://www.ixact.ch/english/pagesnav/IN.htm)