Topics in Advanced Network Security 1 Stateful Intrusion Detection for High Speed Networks Christopher Kruegel Fredrick Valeur Giovanni Vigna Richard Kemmerer Reliable Software Group University of California, Santa Barbara

Topics in Advanced Network Security 2 Overview Introduction Related Work A Slicing Approach for H-S ID Evaluation Conclusion and future work

Topics in Advanced Network Security 3 Introduction Problem Statement –Current IDS are not able to detect attacks on High Speed (Gigabit) networks Why? –Sensor Speed –Architectural Limitations

Topics in Advanced Network Security 4 What is High Speed? Scorpio – Stinger IDS –“ STINGER IDS meets the challenges of watching over a modern network by providing one or more high speed sensors” –Integrated Intel Pro 10/100 Ethernet card (!!!) Symantec Manhunt –Gigabit Detection Intruvert IntrShield 2600 –2.2 GB/sec

Topics in Advanced Network Security 5 IDS Introduction Host Based Network Based Log Based Target Based

Topics in Advanced Network Security 6 Related Work Distributed Sensors USC : 20 snort machines –Therminator : Anomaly based NIDS NetICE Gigabit Sentry – >300 Mbps –500,000 packets/second TopLayer Networks – Switch High Performance NIDS – R. Sekar et al –500 Mbps (Offline Traffic)

Topics in Advanced Network Security 7 Introduction to Slicing Approach Sensors –Misuse detection e.g.: snort –Distributed, Autonomous Slicer –T N = T 1 + T 2 + ….T n –Maintains attack scenarios

Topics in Advanced Network Security 8 System Architecture

Topics in Advanced Network Security 9 System Architecture Tap –Extract link layer frames (F) Scatterer –Partitions F = F j : 0 < j < m Traffic Slicers S 0 ….S m-1 –Route Frames to Sensors : Frame Routing Switch –Forwards packets to channels –Channel = Stream Reassembler + Multiple IDS

Topics in Advanced Network Security 10 System Architecture Stream Reassemblers R 0 ….R n-1 –Prevents Out of Order packets (OOO) –(f j, f k Є FC i ) and (f j before f k ) then j < k Intrusion Detection Sensors I 0 ….I p-1 –Access all packets on channel –Multiple attack scenario ( A j = {A j0 …..A jq-1 } –Attack scenario has Event Space [ES]

Topics in Advanced Network Security 11 Event Space Defines policy for slicers to select channel E jk = c jk0 V c jk1 V ….c jkn c jk =xRy –x value from f i –R arithmetic relation ( =, !=, <) –y constant, value of variable

Topics in Advanced Network Security 12 Frame Routing Splicer filter based on active ES in a channel Static Configuration – Prone to Overloads Dynamic Load Balancing – Reassign ES or subset of ES Example : Destination Attribute

Topics in Advanced Network Security 13 Evaluation Initial Setup –slicer=3, reassembler=4,sensor=1 per stream Scatterer –Intel Xeon 1.7 Ghz, 512 MB RAM, 3Com 996-T, Linux –Kernel Module, Layer 2 Bridge –Inserts Sequence number to source MAC address

Topics in Advanced Network Security 14 Evaluation Traffic Slicer –Intel Pentium Ghz, 256 MB RAM, 3Com 905C- TX (Promiscuous Mode) – Data Portion matched against clauses –Redundant packets generated –Insert Channel Number in Destination MAC Address Test Setup –Internal and External –Internal : 4 Class C address groups

Topics in Advanced Network Security 15 Evaluation Framerouting –Cisco Catalyst 3500XL –Static associations (Channel Number: Port) Reassembler –Timeout Value (500 ms) –No retransmissions

Topics in Advanced Network Security 16 Evaluation Snort Sensor Traffic - MIT Lincoln Labs Traffic Injection – tcpreplay

Topics in Advanced Network Security 17 Snort Performance Snort on tcpdump traffic log Ruleset = 961 rules 11,213 detections in 10 seconds Throughput (offline) =261 Mbps

Topics in Advanced Network Security 18 Snort Performance vs Traffic Rate Snort is run on Scatterer Ruleset = 18 signatures Packetloss at traffic rate of 150 Mbps Snort’s Saturation point

Topics in Advanced Network Security 19 Snort Performance vs Traffic Rate

Topics in Advanced Network Security 20 Snort Perfomance Vs No. of Signatures Traffic rate = 100 Mbps Ruleset –Initial value =18 signatures –Increase number of signatures

Topics in Advanced Network Security 21 Snort Perfomance Vs No. of Signatures

Topics in Advanced Network Security 22 Snort Performance in Proposed Architecture

Topics in Advanced Network Security 23 Snort Performance in Proposed Architecture

Topics in Advanced Network Security 24 Conclusion and Future Work Experimentation in Real World Environment Evaluate the trade-offs Dynamic Load Balancing Hierarchically structured Scatterers/Slicers