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Inferring Strange Behavior from Connectivity Pattern in Social Networks. Meng Jiang, Peng Cui, Shiqiang Yang (Tsinghua, Beijing) Alex Beutel , Christos Faloutsos (CMU). What is Strange Behavior?. “Who-follows-whom” network with billions of edges: Twitter, Weibo , etc.
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Inferring Strange BehaviorfromConnectivityPatterninSocialNetworks MengJiang, PengCui, ShiqiangYang (Tsinghua, Beijing) AlexBeutel,ChristosFaloutsos (CMU)
What is Strange Behavior? • “Who-follows-whom” network with billions of edges: Twitter, Weibo, etc.
What is Strange Behavior? • Sell followers: “Become a Twitter Rockstar” $ $ $ 0.9 TWD per edge
What is Strange Behavior? customer botnet $ connect $ 100 1,000 $
What is Strange Behavior? customer botnet $ connect $ 100 1,000 $ #follower↑+1,000
What is Strange Behavior? customer botnet $ connect $ 100 1,000 $ Unsafe! More customers… 100
What is Strange Behavior? customer botnet $ connect $ 100 1,000 $ More customers… connect 100 5,000
What is Strange Behavior? customer botnet $ connect $ 100 1,000 $ I want more followers… connect 100 5,000
What is Strange Behavior? customer botnet $ connect $ 100 1,000 $ connect connect 100 5,000
What is Strange Behavior? customer botnet $ connect 1,000 100 $ $ 100 5,000 …. …. More groups of customers More groups of botnets More companies….
What is Strange Behavior? customer botnet $ connect $ $ Detectdense biparitite cores! How can we evade detection? Some other activity!
What is Strange Behavior? customer botnet $ connect $ $ “Camouflage”: may connect to popular idols to look normal
What is Strange Behavior? customer botnet $ connect $ $ “Fame”: may have a few honest followers
AdjacencyMatrixReminder followee follower Graph Structure Adjacency Matrix
Strange Lockstep Behavior customer botnet • Groups • Acting together • Little other activity connect camouflage fame
More Applications • eBay reviews
More Applications • Facebook “Likes”
Problem Definition • Givenadjacencymatrix • FindStrange=“Lockstep”Behavior reordering
Outline • Method • SVDReminder • “SpectralSubspacePlot” • BP-basedAlgorithm • Experiments • Dataset • RealData • SyntheticData
SVD Reminder followee 1 follower follow 2 Graph Structure Adjacency Matrix SVD:A=USVT Pairsofsingularvectors: followee U2 V2 U1U2 … V1V2 U1 V1 follower “SpectralSubspacePlot”
Outline • Method • SVDReminder • “SpectralSubspacePlot” • BP-basedAlgorithm • Experiments • Dataset • RealData • SyntheticData
Lockstep and SpectralSubspacePlot • Case#0:Nolockstepbehaviorinrandompowerlawgraphof1Mnodes,3Medges • Random“Scatter” Adjacency Matrix SpectralSubspacePlot
Lockstep and SpectralSubspacePlot • Case#1:non-overlappinglockstep • “Blocks”“Rays” Adjacency Matrix SpectralSubspacePlot
Lockstep and SpectralSubspacePlot • Case#2:non-overlappinglockstep • “Blocks;lowdensity”Elongation Adjacency Matrix SpectralSubspacePlot
Lockstep and SpectralSubspacePlot • Case#3:non-overlappinglockstep • “Camouflage” (or “Fame”)Tilting“Rays” Adjacency Matrix SpectralSubspacePlot
Lockstep and SpectralSubspacePlot • Case#3:non-overlappinglockstep • “Camouflage” (or “Fame”)Tilting“Rays” Adjacency Matrix SpectralSubspacePlot
Lockstep and SpectralSubspacePlot • Case#4:?lockstep • “?”“Pearls” Adjacency Matrix SpectralSubspacePlot ?
Lockstep and SpectralSubspacePlot • Case#4:overlappinglockstep • “Staircase”“Pearls” Adjacency Matrix SpectralSubspacePlot
Outline • Method • SVDReminder • “SpectralSubspacePlot” • BP-basedAlgorithm • Experiments • Dataset • RealData • SyntheticData
Algorithm • Step1:Seedselection • Spot“Rays”and“Pearls” • Catchseedfollowers • Step2:BeliefPropagation • Blamefolloweeswithstrangefollowers • Blamefollowerswithstrangefollowees
AutomaticallySpot“Rays”and“Pearls” Spectral SubspacePlot PolarCoordinate Transform Histograms
BP-basedAlgorithm • Blame followees with strange followers • Blame followers with strange followees
Outline • Method • SVDReminder • “SpectralSubspacePlot” • BP-basedAlgorithm • Experiments • Dataset • RealData • SyntheticData
Dataset • TencentWeibo • 117 million nodes(users) • 3.33billiondirectededges
Outline • Method • SVDReminder • “SpectralSubspacePlot” • BP-basedAlgorithm • Experiments • Dataset • RealData • SyntheticData
Real Data “Block” “Rays” “Pearls” “Staircase”
Real Data “Rays” “Block”
Real Data “Pearls” • 3,188 • in F1 • 7,210 • in F2 • 2,457 • in F3 “Staircase” • E1 E2E3E4
Real Data “Pearls” “Staircase” “Staircase”
RealData • Spikesontheout-degreedistribution
Outline • Method • SVDReminder • “SpectralSubspacePlot” • BP-basedAlgorithm • Experiments • Dataset • RealData • SyntheticData
Synthetic Data • Injectlockstepbehaviorwith“camouflage” perfect
Synthetic Data • Injectoverlapping lockstepbehavior perfect
Contributions • Differenttypesoflockstepbehavior • Ahandbook(rules)toinferlockstepbehaviorwithconnectivitypatterns • Analgorithmtocatchthesuspiciousnodes • Removespikesonout-degreedistribution