Enhancing security and privacy in online social networksSonia Jahid
Social networks have traditionally had some strange ways of dealing with security and privacy, and bring new challenges. How do we handle it if you leave a comment on a private photo and that later becomes public? Right now many networks would make the comment public, but does that make sense?
Sonia Jahid notes that one of the oddities of the social network is that traditionally we don't go through a 3rd party to talk to our friends, and some of the challenges towards a private and secure social network stem from that change. She proposes looking at a more decentralized model, but this forces us to make new decisions and answer new questions. For example, where is data going to be stored? (will I keep it myself? what if I'm offline?) What does access control mean for social networks? How do those models change if the network is decentralized? How can one efficiently provide something like a news feed for a distributed network?
I think one of the key insights of this talk is that while these questions may not seem that urgent for a facebook status update (what if you don't care about those?), many of these questions come up in other applications. For example, medical record sharing can be likened to a social network, where patients, doctors, hospitals, specialists, etc. all want to share some data while keeping other data private. And bringing the problem into the healthcare space brings other challenges: what if we need a "in case of emergency break glass" policy where if the patient is hospitalized while traveling, her medical data can still be accessed by the hospital that admits her. What if the patient wishes to see an audit listing everyone who has accessed her data? (How can we make that possible while keeping that information private from other folk?)
There's clearly some really interesting problems in this space!Securing Online Reputation SystemsYuhong Liu
Trust exists between people who know each other, but what if we want to trust people we may not know? This is the goal of reputation systems, but these ratings can be easily manipulated. Yuhong Liu points out a movie rating that was exceptionally high while the movie was during its promotional period, but fell rapidly once it had been out a while. Her research includes detecting such ratings manipulation.
For a single attacker, common strategies include increasing the cost of obtaining single userids, investigating statistically aberrant ratings, or giving users trust values, but all of these can be worked around, so Yuhong Liu's research includes a defense where she builds a statistical model based on the idea that items have intrinsic quality which is unlikely to change rapidly. She found that colluding users often share statistical patterns, making it possible to detect them.
One of the interesting things about this talk was a question from the audience about the complexity of this model: Because the first pass of the model uses a threshold to determine areas of interest in the ratings, we can avoid doing larger checks constantly and can focus only on regions of interest, making this much more feasible as far as run time goes. Handy!On Detecting DeceptionSadia Afroz
Deception: adversarial behaviour that disrupts regular behaviour of a system
Sadia Afroz's work involves detecting deception three areas:
1. in writing where an author pretends to be another author.
2. websites pretending to be other webites (phishing)
3. blog comments (are the legit or are they spam?)
All of these are interesting cases, but I was most fascinated by the fact that her algorithm was fairly good at detecting short-term detection (e.g. a single article aping someone else's style) but had more difficulty detecting long-term deception like in the case of Amina/Thomas MacMaster. (This might be interesting to badgerbag
?) Are long-term personas actually a different type of "deception" ?
All in all, lots of food for thought in this session. I've also uploaded my raw notes to the GHC12 wiki
in case anyone wants a bit more detail than in this blog post.Note
: If you're one of the speakers and feel I accidentally mis-represented your talk or want me to remove a photo of you for any reason, please contact me at terri(a)zone12.com and I'd be happy to get things fixed for you!