Worm Origin Identification Using Random Moonwalks

Yinglian Xie, V. Sekar, D. A. Maltz, M. K. Reiter, Hui Zhang

2005 IEEE Symposium on Security and Privacy

Presented by: Presented by:

Anup GoyalAnup Goyal

Edward MerchantEdward Merchant

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Outline Motivation/IntroductionMotivation/Introduction Problem FormulationProblem Formulation The Random Moonwalk AlgorithmThe Random Moonwalk Algorithm Evaluation MethodologyEvaluation Methodology Analytical ModelAnalytical Model Real Trace StudyReal Trace Study Simulation StudySimulation Study Deployment and Future WorkDeployment and Future Work

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Outline Motivation/IntroductionMotivation/Introduction Problem FormulationProblem Formulation The Random Moonwalk AlgorithmThe Random Moonwalk Algorithm Evaluation MethodologyEvaluation Methodology Analytical ModelAnalytical Model Real Trace StudyReal Trace Study Simulation StudySimulation Study Deployment and Future WorkDeployment and Future Work

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Motivation Little automated support for identifying the

location from which an attack is launched.

Knowledge of the origin support law enforcement.

Knowledge of the casual flow that advance attack supports diagnosis of how network defense is breached.

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Introduction

We craft an algorithm that determines the origin of epidemic spreading attacks.

identify the “patient zero” of the epidemic reconstruct the sequence of spreading

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Introduction (cont’d)

Random moonwalk algorithm - Find the origin and propagation paths of a worm attack.

performs post-mortem analysis on the traffic records logged by the network.

It depends on the assumption that worm propagation occurs in a tree-like structure.

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Outline IntroductionIntroduction Problem FormulationProblem Formulation The Random Moonwalk AlgorithmThe Random Moonwalk Algorithm Evaluation MethodologyEvaluation Methodology Analytical ModelAnalytical Model Real Trace StudyReal Trace Study Simulation StudySimulation Study Deployment and Future WorkDeployment and Future Work

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Problem Formulation

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Problem Formulation (cont’d)

A directed host contact graph G = (V, E)G = (V, E) V = H × TV = H × T

HH is the set of all hosts in the network TT is time

Each directed edge represents a network flow between two end hosts at certain time. flow has a finite duration, and involves transfer

of one or more packets. e = (u, v, te = (u, v, tss, t, tee))

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Problem Formulation (cont’d)

normal edge The flow does not carry an infectious payload.

attack edge The flow carries attack traffic, whether or not the

flow is successful. causal edge

The flow that actually infect its destination.

Goal - Identify a set of edges that are edges from the top level of the casual tree.

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Outline IntroductionIntroduction Problem FormulationProblem Formulation The Random Moonwalk AlgorithmThe Random Moonwalk Algorithm Evaluation MethodologyEvaluation Methodology Analytical ModelAnalytical Model Real Trace StudyReal Trace Study Simulation StudySimulation Study Deployment and Future WorkDeployment and Future Work

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Random Moonwalk Algo. Causal relationship between flows by exploiting the

global structure of worm attacks No use of attack content, attack packet size, or port

numbers

For attack progress, there has to be a communication link between source of the attack and compromised nodes

This infection causing communication flows form a causal tree, rooted at the source of attack.

Find the tree and root is the source of attack Find causal flows and attack flows

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Random Moonwalk Algo. Basic Algorithm

Go backward from every node for certain distance.

At each node choose only the flows which are within certain time limit

Do it Z number of times Find the edges with highest frequency Create a tree for these flows

Most probably this is the causal tree and root is the source of attack

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Random Moonwalk Algo. (cont’d)

Sampling process controlled by three parameters

W – the number of walks (samples) performed.

D – maximum length of the path traversed.

Δt Δt - - sampling window size, max. time allowed between two consecutive edges

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Random Moonwalk Algo. (cont’d)

Why this algorithm works ?

To propagate, sometime after infection, worm creates a new flows to other hosts.

This forms a link from source to last victim

Traverse this link backward and find the source

An infected host generally originates more flows than it receives.

The originators host contact graph are mostly clients. Normal edges have no predecessor within ΔtΔt.

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Outline IntroductionIntroduction Problem FormulationProblem Formulation The Random Moonwalk AlgorithmThe Random Moonwalk Algorithm Evaluation MethodologyEvaluation Methodology Analytical ModelAnalytical Model Real Trace StudyReal Trace Study Simulation StudySimulation Study Deployment and Future WorkDeployment and Future Work

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Outline

Evaluation MethodologyEvaluation Methodology Analytical ModelAnalytical Model

AssumptionsAssumptions Edge Probability DistributionEdge Probability Distribution False Positives and False NegativesFalse Positives and False Negatives Parameter SelectionParameter Selection

Real Trace StudyReal Trace Study Simulation StudySimulation Study

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Analytical Model (Assumptions)

The host contact graph is known. |E||E| edges and |H||H| hosts

Discretize time into units. Every flow has a length of one unit and fits into one unit.

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Analytical Model (Probability)

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Analytical Model (FP & FN)

(42 malicious edges at k = 1.) (Total 105 host.)

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Outline Evaluation MethodologyEvaluation Methodology Analytical ModelAnalytical Model Real Trace StudyReal Trace Study

Detect the Existence of an AttackDetect the Existence of an Attack Identify Casual Edges & Initial Infected HostIdentify Casual Edges & Initial Infected Host Reconstruct the Top Level Casual TreeReconstruct the Top Level Casual Tree Parameter SelectionParameter Selection PerformancePerformance

Simulation StudySimulation Study

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Real Trace Study Background Traffic

Traffic trace was collected over a 4 hour period at backbone of a class-B university network.

collect intra-campus flows only (1.4 million) involving 8040 hosts

Addition Add flow records to represent worm-like traffic

with vary scanning rate randomly select the vulnerable hosts.

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Real Trace Study (Existence)

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Real Trace Study (Identify)

(800 causal edges from 1.5*106 flows)(The scanning rate of Trace-50 is less than Trace-10.)

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Real Trace Study (Identify)

Top frequent sampling v.s. Actual initial edges

(total 800 causal edges, initial 10% are the first 80 edges)(The scanning rate of Teace-50 is less than Trace-10.)

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Top 60, Trace-50, 104 walks

Blaster Worm scan

Original Attacker

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Real Trace Study (Parameter)

dd and ΔtΔt

d = infinite

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Real Trace Study (Performance)

Random moonwalk Z = 100, 104 walks

Heavy-hitter Find 800 hosts with largest number of flows in

the trace, random pick 100 flows Super-spreader

Find 800 hosts contacted the largest number of destination, randomly pick 100 flows

Oracle With zero false positive rate, randomly select

100 flows between infected hosts

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Real Trace Study (Performance)

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Real Trace Study (Performance)

Scanning Method Smart worm (always scan valid hosts), R↑R↑ Scan with random address

C: casual edgeA: attack edge100: Z=100500: Z=500

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Outline Evaluation MethodologyEvaluation Methodology Analytical ModelAnalytical Model Real Trace StudyReal Trace Study Simulation StudySimulation Study

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Simulate different background traffic Realistic host contact graphs tend to be much

sparser, meaning the chance of communication between two arbitrary hosts is very low.

Simulation StudySimulation Study

p.s. in campus network,the accuracy is about 0.7

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Outline IntroductionIntroduction Problem FormulationProblem Formulation The Random Moonwalk AlgorithmThe Random Moonwalk Algorithm Evaluation MethodologyEvaluation Methodology Analytical ModelAnalytical Model Real Trace StudyReal Trace Study Simulation StudySimulation Study Deployment and Future WorkDeployment and Future Work

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Deployment and Future Work

This approach assumes that the availability of complete data. the missing data on performance the deployment of the algorithm

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Questions ????

Thank You