IPS50SL07.ppt - Lesson 7 Describing Signature Engines 2005...

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© 2005 Cisco Systems, Inc. All rights reserved. IPS v5.0—7-1 Lesson 7 Describing Signature Engines
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© 2005 Cisco Systems, Inc. All rights reserved. IPS v5.0—7-2 Signature Engines
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© 2005 Cisco Systems, Inc. All rights reserved. IPS v5.0—7-3 Signature Engine Overview A Signature Engine is a component of the sensor that supports a category of signatures. The Cisco IPS Signature Engines enable you to tune built-in signatures and create new signatures unique to your network environment.
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© 2005 Cisco Systems, Inc. All rights reserved. IPS v5.0—7-4 Engine Usage Engine Category Usage Atomic Used for single-packet inspection Flood Used to detect attempts to cause a DoS Meta Used to perform event correlation on the sensor Normalizer Used to detect ambiguities and abnormalities in the traffic stream
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© 2005 Cisco Systems, Inc. All rights reserved. IPS v5.0—7-5 Engine Usage (Cont.) Engine Category Usage Service Used when Layer 5, 6, and 7 services require protocol analysis State Used for state-based and regular expression–based pattern inspection and alarming functionality for TCP streams String Used for regular expression–based pattern inspection and alarm functionality for multiple transport protocols
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© 2005 Cisco Systems, Inc. All rights reserved. IPS v5.0—7-6 Engine Usage (Cont.) Engine Category Usage Sweep Used to detect network reconnaissance Traffic Used to detect traffic irregularities Trojan Used to inspect nonstandard protocols AIC Used for deep-packet inspection of FTP and HTTP traffic
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© 2005 Cisco Systems, Inc. All rights reserved. IPS v5.0—7-7 Engine Parameters An engine parameter is a name and value pair. The parameter name is defined by its engine. Parameter values have limits that are defined by the engine. The parameter name is constant across all signatures in a particular engine, but the value can be different for the various signatures in an engine group. Some parameters are common to all engines while others are engine-specific.
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© 2005 Cisco Systems, Inc. All rights reserved. IPS v5.0—7-8 Atomic Signature Engines
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© 2005 Cisco Systems, Inc. All rights reserved. IPS v5.0—7-9 Atomic Signature Engines Engine Name Engine Description Atomic ARP Examines ARP packets Atomic IP Examines ICMP, IP, TCP, and UDP packets
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© 2005 Cisco Systems, Inc. All rights reserved. IPS v5.0—7-10 Atomic ARP Parameters Specify Type of ARP Sig Specify Request Inbalance Storage Key
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© 2005 Cisco Systems, Inc. All rights reserved. IPS v5.0—7-11 Atomic IP Parameters Specify Layer 4 Protocol Fragment Status: Not Fragmented Layer 4 Protocol: TCP Protocol TCP Flags: SYN TCP Mask: Syn, Ack Specify Payload Inspection
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© 2005 Cisco Systems, Inc. All rights reserved. IPS v5.0—7-12 Flood Signature Engines
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© 2005 Cisco Systems, Inc. All rights reserved. IPS v5.0—7-13 Flood Signature Engines Engine Name Engine Description Flood Net Looks for an excessive number of packets sent to a network segment Flood Host Looks for an excessive number of ICMP or UDP packets sent to a target host
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© 2005 Cisco Systems, Inc. All rights reserved. IPS v5.0—7-14 Flood Net Parameters Gap Peaks Rate Protocol
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© 2005 Cisco Systems, Inc. All rights reserved. IPS v5.0—7-15 Flood Host Parameters Rate: 25 Protocol: ICMP ICMP Type: 8
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© 2005 Cisco Systems, Inc. All rights reserved. IPS v5.0—7-16 Meta Signature Engine
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© 2005 Cisco Systems, Inc. All rights reserved.
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