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Seminar on<br />Intrusion<br />Detection<br />System<br />

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Topics:<br /><ul><li>Introduction of IDS

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Technologies

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Detection types</li></li></ul><li>Introduction<br /><ul><li>What is IDS?

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History

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Need of IDS

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Classification of IDS</li></li></ul><li>What is IDS?<br /><ul><li>Revolution in networking

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The possibilities and opportunities are limitless.

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Unfortunately, so too are the risks and chances of malicious activities.</li></li></ul><li><ul><li>Intrusion=Illegal entry or unwelcome addition

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Definition:</li></ul> Intrusion Detection System (IDS) is a software to determine if a computer network or server has experienced an unauthorized intrusion.<br />

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IDS detects these intrusion attempts so that action may be takento repair the damage later.<br /> IDS monitors network traffic and monitors for suspicious activity and alerts the system or network administrator.<br />

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The beginning(History)<br />A USAF paper published in October 1972 written by James P. Anderson outlined the fact the USAF had “become increasingly aware of computer security problems.”<br />

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<ul><li>Before designing an IDS, it was necessary to understand the types of threats and attacks that could be mounted against computers systems.</li></li></ul><li><ul><li>A computer system should provide confidentiality, integrity and assuranceagainst denial of service.

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Confidentiality:</li></ul>Whether the information stored on a system is protected against unauthorized access.<br />Need of IDS<br />

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<ul><li>Integrity:</li></ul> Whether the information stored on a system is reliable and can be trusted.<br /><ul><li>Increased connectivity: (especially on the Internet)</li></ul> more and more systems are subject to attack by intruders. <br /> <br />

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<ul><li>These intruders attempts try to exploit flaws in the OS as well as in application programs and have resulted in spectacular incidents.

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Internet Worm incident of 1988.</li></li></ul><li>Two ways to handle<br />

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<ul><li>we cannot prevent intruders,we should at least try to detect it and prevent similar attacks in future.</li></li></ul><li>Types of intruders<br />

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Tasks to be performed<br />Simulation<br />Analysis<br />Notification<br />

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Technologies:<br />

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Network Intrusion detection system<br /><ul><li>Detect attacks as they happen

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Real-time monitoring of networks

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Provide information about attacks that have succeeded

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Forensic analysis</li></li></ul><li><ul><li>Deploying sensors at strategic locations

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E.G., Packet sniffing via tcpdump at routers

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Inspecting network traffic

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Watch for violations of protocols and unusual connection patterns

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Monitoring user activities

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Look into the data portions of the packets for malicious command sequences</li></li></ul><li>

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May be easily defeated by encryption<br />Data portions and some header information can be encrypted<br />The decryption engine still there.<br />

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Related Tools for Network IDS <br /><ul><li>While not an element of Snort, Ethereal is the best open source GUI-based packet viewer

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www.ethereal.com offers:

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Windows

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UNIX, e.g., www.ethereal.com/download.html

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Red Hat Linux RPMs: ftp.ethereal.com/pub/ethereal/rpms</li></li></ul><li>

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Requirements of NIDS<br /><ul><li>High-speed, large volume monitoring

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No packet filter drops

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Real-time notification

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Mechanism separate from policy

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Extensible

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Broad detection coverage

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Economy in resource usage

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Resilience to stress

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Resilience to attacks upon the IDS itself!</li></li></ul><li>Host Intrusion Detection System<br /><ul><li>Using OS auditing mechanisms

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E.G., BSM on Solaris: logs all direct or indirect events generated by a user

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strace for system calls made by a program

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Monitoring user activities

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E.G., Analyze shell commands</li></li></ul><li><ul><li>Monitoring executions of system programs

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E.G., Analyze system calls made by sendmail

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A HIDS can see more than just network traffic and can make decisions based on local settings, settings specific to an OS, and log data. </li></li></ul><li>

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Signature based ids<br /><ul><li>Sniff traffic on network

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border router or multiple sensors within a LAN

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Match sniffed tracffic with signatures

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attack signatures in database

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Signature: set of rules pertaining to a typical intrusion activity

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Simple example rule: any ICMP packet > 10,000 bytes

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Example: more than one thousand SYN packets to different ports on same host under a second</li></li></ul><li><ul><li>skilled security engineers research known attacks; put them in database

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can configure IDS to exclude certain signatures; can modify signature parameters

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Warn administrator when signature matches.

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send e-mail, SMS

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send message to network management system</li></li></ul><li>Limitations to signature detection<br /><ul><li>Requires previous knowledge of attack to generate accurate signature

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Blind to unknown attacks

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Signature bases are getting larger

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Every packet must be compared with each signature

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IDS can get overwhelmed with processing; can miss packets</li></li></ul><li>Anomaly Detection IDS<br /><ul><li>Observe traffic during normal operation

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Create normal traffic profile

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Look for packet streams that are statistically unusual

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e.g., inordinate percentage of ICMP packet

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or exponential growth in port scans/sweeps

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Doesn’t rely on having previous knowledge of attack

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Research topic in security</li>