  As the COVID-19 pandemic started triggering widespread lockdowns across the
globe, cybercriminals did not hesitate to take advantage of users' increased
usage of the Internet and their reliance on it. In this paper, we carry out a
comprehensive measurement study of online social engineering attacks in the
early months of the pandemic. By collecting, synthesizing, and analyzing DNS
records, TLS certificates, phishing URLs, phishing website source code,
phishing emails, web traffic to phishing websites, news articles, and
government announcements, we track trends of phishing activity between January
and May 2020 and seek to understand the key implications of the underlying
trends.
  We find that phishing attack traffic in March and April 2020 skyrocketed up
to 220\% of its pre-COVID-19 rate, far exceeding typical seasonal spikes.
Attackers exploited victims' uncertainty and fear related to the pandemic
through a variety of highly targeted scams, including emerging scam types
against which current defenses are not sufficient as well as traditional
phishing which outpaced the ecosystem's collective response.
