When socialbots attack: Modeling susceptibility of users in online social networks Claudia Wagner, Silvia Mitter, Christian Körner, Markus Strohmaier Lyon, 16.4.2012
When socialbots attack:
Modeling susceptibility of users in online social networksClaudia Wagner, Silvia Mitter, Christian Körner, Markus Strohmaier
Lyon, 16.4.2012
What are socialbots?A socialbot is a piece of software that controls a user account in an online social network and passes itself of as a human being
3Danger of socialbots
Social EngineeringGaining access to secure objects by exploiting human psychology rather than using hacking techniques
Harvest private user data such as email addresses, phone numbers, and other personal data that have monetary value
Spread MisinformationRatkiewicz et al. describe the use of Twitter bots to run smear campaigns during the 2010 U.S. midterm elections.
J. Ratkiewicz, M. Conover, M. Meiss, B. Goncalves, S. Patil, A. Flammini, and F. Menczer. Truthy: mapping the spread of astroturf in microblog streams. In Proceedings of the 20th international conference companion on World wide web, WWW '11, pages
Danger of socialbots
Snowball effectsBoshmaf et al. show that Facebook can be infiltrated by social bots sending friend requests. 102 socialbots, 6 weeks, 3.517 friend requests and 2.079 infections
Average reported acceptance rate: 59,1% up to 80% depending on how many mutual friends the social bots had with the infiltrated users
Y. Boshmaf, I. Muslukhov, K. Beznosov, and M. Ripeanu. The socialbot network. In Proceedings of the 27th Annual Computer Security Applications Conference, page 93. ACM Press, Dec 2011.
Experimental SetupHow likely will she
be infected by a bot ?
Is she a bot?
Whom shall we protect to avoid large scale infiltration due to snowball effects?
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Who is a bot? Whom shall we eliminate?
Experimental Setup
Two-stage approachPredict Infections (binary classification task)
Who is susceptible for bot attacks – i.e. who gets infected?
Predict Infection level (regression task)
How susceptible is a user – i.e. how often does a user interact with bots?
Dataset: Social Bot Challenge 2011
Social Bot Challenge 2011Competition organized by Tim Hwang
Aim was to develop socialbots that persuade 500 randomly Twitter users (targets) to interact with them
Targets have a topic in common: cats
Teams got points if targets replied to, mentioned, retweeted or followed their lead bot
14 days during which teams were allowed to develop their social bots.
Game started on the Jan 23rd 2011 (day 1) and ended Feb 5th 2011 (day 14)
At the 30th of January (day 8) the teams were allowed to update their codebase
Dataset
Feature EngineeringHow likely will this user become infected?
Behavior
User Network
Content
Network Features3 directed networks: Follow, retweet and interaction (retweet, reply, mention and follow) network
Hub and Authority Score (HITS)High authority score node has many incoming edges from nodes with a high hub score
High hub score node has many outgoing edges to nodes with a high authority score
In-degree and Out-degree
Clustering Coefficientnumber of actual links between the neighbors of a node divided by the number of possible links between them
Behavioral Features
Informational Coverage
Conversational Coverage
Question Coverage
Social Diversity
Informational Diversity
Temporal Diversity
Lexical Diversity
Topical Diversity
C. Wagner and M. Strohmaier. The wisdom in tweetonomies: Acquiring latent conceptual structures From social awareness streams. In Proc. of the Semantic Search 2010 Workshop, April 2010.
Linguistic FeaturesLIWC uses a word count strategy searching for over 2300 words
Words have previously been categorized into over 70 linguistic dimensions.
standard language categories (e.g., articles, prepositions, pronouns including first person singular, first person plural, etc.)
psychological processes (e.g., positive and negative emotion categories, cognitive processes such as use of causation words, self-discrepancies),
relativity-related words (e.g., time, verb tense, motion, space)
traditional content dimensions (e.g., sex, death, home, occupation).
J. Pennebaker, M. Mehl, and K. Niederhoer. Psychological aspects of natural language use: Our words, our selves. Annual review of psychology, 54(1):547-577, 2003.
Feature Computation
For all targets we computed the features by using all tweets they authored during the challenge (up to the point in time where they become infected) and a snapshot of the follow network which was as recorded at the 26th of January (day 4)
We only used targets which became susceptible at day 7 or later
Features do not contain any future information (such as tweets or social relations which were created after a user became infected)
Predict InfectionsBinary Classification of users into susceptible and non-susceptible
Train 6 classifiers
97 Features
Compare classifiers via 10 cross-fold validation
Balanced dataset
Feature Ranking
AUC value as ranking criterion
Top 10 Features
Social and active
Meformer
Communicative and open
Emotional
Predict Level of Infection
Which factors are correlated with users‘ susceptibility score?
Susceptibility score counts number of interactions between a target and any lead bot
Method: Regression Treescan handle strongly nonlinear relationships with high order interactions and different variable types
Fit the model to our 75% of the susceptible users
Predicting Levels of Susceptibility
Users who • use more negation words (e.g. not, never, no), • tweet more regularly (i.e. have a high temporal balance) • use more words related with the topic death (e.g. bury, con, kill)tend to interact more often with bots
Predicting Levels of SusceptibilityRank correlation of hold-out users given their real susceptibility level and their predicted susceptibility level (Kendall τ up to 0.45)
Goodness of fit (R2 up to 0.3)
Potential Reasons:
Dataset is too small (we only had 81 susceptible users and 61% of them had level 1, 17% had level 2, 10% had level 3, very few users had more than 3 interactions)
Summary & Conclusions
Approach to identify susceptible users
Features of all three types contributed to the identification
Users are more likely to be susceptible ifthey are emotional Meformers
they use Twitter mainly for communicating
their communications are not focused to a small circle of friends
they are social and active (i.e., interact with many others)
Summary & Conclusions
Active Twitter users are more susceptible They are more likely to see the messages/requests of social bots
But we expected that they develop some skills to distinguish social bots from human by using Twitter frequently
Predicting users’ susceptibility score is difficult More data and further experiments are required
Future Work
Repeating experiments on larger datasets
Taxonomy of social bot strategiesMassive numbers of con-messages (brute force)
Manipulation of messages through false retweets (changing pro- to con messages)
Diverting attention by adding con-hashtags to pro-hashtags
Susceptibility of users for different strategies
Experimental Setup
THANK YOU
[email protected]://claudiawagner.info
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Emotional Meformers which are active, communicative and social are more likely to be infected