Title: Cyber Risk Analysis of Combined Data Attacks Against Power System State Estimation,
Abstract: Understanding smart grid cyber attacks is key for developing appropriate
protection and recovery measures. Advanced attacks pursue maximized impact at
minimized costs and detectability. This paper conducts risk analysis of
combined data integrity and availability attacks against the power system state
estimation. We compare the combined attacks with pure integrity attacks - false
data injection (FDI) attacks. A security index for vulnerability assessment to
these two kinds of attacks is proposed and formulated as a mixed integer linear
programming problem. We show that such combined attacks can succeed with fewer
resources than FDI attacks. The combined attacks with limited knowledge of the
system model also expose advantages in keeping stealth against the bad data
detection. Finally, the risk of combined attacks to reliable system operation
is evaluated using the results from vulnerability assessment and attack impact
analysis. The findings in this paper are validated and supported by a detailed
case study.