MCA 2: Multi Core Architecture for Mitigating Complexity Attacks Yaron Koral (TAU) Joint work with: Yehuda Afek (TAU), Anat Bremler-Barr (IDC), David Hay (HUJI) and Yotam Harchol (HUJI)

A multicore system architecture, which is robust against complexity DDoS attacks

Network Intrusion Detection System Reports or drops malicious packets Important technique: Deep Packet Inspection (DPI) 3 Internet IP packet IP packet

Complexity DoS Attack Over NIDS Find a gap between average case and worst case One may craft an input that exploits this gap Launch a Denial of Service attack on the system 4 Internet Real-Life Traffic Throughput

Attack on Security Elements Combined Attack: DDoS on Security Element exposed the network – theft of customers’ information

Attack on Snort The most widely deployed IDS/IPS worldwide. Max Throughput Routine Traffic Heavy Packet Traffic

Airline Desk Example

A flight ticket

Airline Desk Example An isle seat near window!! Three carry handbags !!! Doesn’t like food!!! Can’t find passport!! Overweight!!!

Airline Desk Example

Domain Properties 1.Heavy & Light customers. 2.Easy detection of heavy customers. 3.Moving customers between queues is cheap. 4.Heavy customers have special more efficient processing method. Domain Properties 1.Heavy & Light packets. 2.Easy detection of heavy packets 3.Moving packets between queues is cheap. 4.Heavy packets have special more efficient processing method. Special training

Some packets are much “heavier” than others The Snort-attack experiment

DPI mechanism is a main bottleneck in Snort Allows single step for each input symbol Holds transition for each alphabet symbol Snort uses Aho-Corasick DFA Heavy Packet Fast & Huge Best for normal traffic Exposed to cache-miss attack Best for normal traffic Exposed to cache-miss attack

Snort-Attack Experiment Cache Main Memory Normal TrafficAttack Scenario Max Throughput Routine Traffic Heavy Packet Traffic

The General Case: Complexity Attacks Building the packet is much cheaper than processing it. Domain Properties 1.Heavy & Light packets. 2.Easy detection of heavy packets 3.Moving packets between queues is cheap. 4.Heavy packets have special more efficient processing method.

Detecting heavy packets is feasible

How Do We Detect? Normal and heavy packets differ from each other May be classified quickly Claim: the general case in complexity attacks!!! threshold

Domain Properties 1.Heavy & Light packets. 2.Easy detection of heavy packets 3.Moving packets between queues is cheap. 4.Heavy packets have special more efficient processing method.

System Architecture Processor Chip Core #8 Dedicated Core #9 NIC Core #1 Q Core #2 Q Q Q B Dedicated Core #10 B Q Routine and alert mode Drop mode Dynamic thread allocation model Non blocking queue synchronization Move packets between cores with negligible overhead! Detects heavy packets

Domain Properties 1.Heavy & Light packets. 2.Easy detection of heavy packets 3.Moving packets between queues is cheap. 4.Heavy packets have special more efficient processing method.

Snort uses Aho-Corasick DFA

Full Matrix vs. Compressed

Domain Properties 1.Heavy & Light packets. 2.Easy detection of heavy packets 3.Moving packets between queues is cheap. 4.Heavy packets have special more efficient processing method.

Experimental Results

System Throughput Over Time

Different Algorithms Goodput

Concluding Remarks A multi-core system architecture, which is robust against complexity DDoS attacks In this talk we focused on specific NIDS and complexity attack Additional results show how the system fits to other cases: – Hybrid-FA – Bro Lazy-FA We believe this approach can be generalized (outside the scope of NIDS).

Thank You!!