  In the world's largest-ever deployment of online voting, the iVote Internet
voting system was trusted for the return of 280,000 ballots in the 2015 state
election in New South Wales, Australia. During the election, we performed an
independent security analysis of parts of the live iVote system and uncovered
severe vulnerabilities that could be leveraged to manipulate votes, violate
ballot privacy, and subvert the verification mechanism. These vulnerabilities
do not seem to have been detected by the election authorities before we
disclosed them, despite a pre-election security review and despite the system
having run in a live state election for five days. One vulnerability, the
result of including analytics software from an insecure external server,
exposed some votes to complete compromise of privacy and integrity. At least
one parliamentary seat was decided by a margin much smaller than the number of
votes taken while the system was vulnerable. We also found protocol flaws,
including vote verification that was itself susceptible to manipulation. This
incident underscores the difficulty of conducting secure elections online and
carries lessons for voters, election officials, and the e-voting research
community.
