Transcript Security II
Lecture 5: Cloud Security: what’s new? Xiaowei Yang (Duke University) Recap • Exploring information leakage in thirdparty compute clouds – Placement – Determining co-residence – Inferrence Placement • Launching test instances • Determining the correlation between instance placement and IP addresses • Launching many probe instances in the same availability zone Determining co-residence • Traceroute Cross-VM information leakage • Load measurement: Prime-Trigger-Probe – B: buffer of size b; s: cache line size 1. Prime: Read B at s-offset 2. Trigger: busy-loop until swapped out 3. Probe: measure the time it takes to read B again at s-offset – If it takes long – If it does not take long Load-based co-residence detection • Send http requests to a target VM • Do load measurement – High – Low Which one(s) shows co-resident? Estimating traffic rates • High traffic rates high load Keystroke timing attack • Hypothesis – On an idle machine, • High load spike keystroke input • Timing between high load spikes timing between keystrokes • Timing between keystrokes infers password Summary • Co-residence information leak • Defending against it is hard WHAT’S NEW ABOUT CLOUD COMPUTING SECURITY? Overview • New threats • New research opportunities New threats • A more reliable alternative to botnets – If cloud computing is cheaper and more reliable than botnets, use cloud • Brute-forcer • Resource sharing and interference – Placement, inferrence • Reputation fate sharing – Spammers block other legitimate services – An FBI raid Novel elements • Protecting data and software is not enough Activity pattern needs protection as well • Reputation attribution • A longer trust chain • Competitiveness business may co-locate Is mutual auditability a solution? • Provider audits customer’s activities • Customer audits what a provider provides • enables attribution of blame New opportunities • Cloud providers should offer a choice of security primitives – Granularity of virtualizations • Physical machines, LANS, clouds, or datacenters • Mutual auditability – Provider audits customer’s activities – Customer audits what a provider provides – enables attribution of blame • Studying cloud security vulnerabilities Next • Discovering VM dependencies using CPU utilization – Question to ponder: can this technique be used a security attack? Interesting techniques • Inference technique – Auto-regressive modeling: use past samples to predict future values – Compute distances of AR models • Models with similar coefficients are closer – K-mean clustering • Perturbation to improve inference accuracy Security attacks • • • • Achieving co-residence Do load measurements Figure out service correlations DoS all related services