  There has been a huge spike in the usage of social media platforms during the
COVID-19 lockdowns. These lockdown periods have resulted in a set of new
cybercrimes, thereby allowing attackers to victimise social media users with a
range of threats. This paper performs a large-scale study to investigate the
impact of a pandemic and the lockdown periods on the security and privacy of
social media users. We analyse 10.6 Million COVID-related tweets from 533 days
of data crawling and investigate users' security and privacy behaviour in three
different periods (i.e., before, during, and after the lockdown). Our study
shows that users unintentionally share more personal identifiable information
when writing about the pandemic situation (e.g., sharing nearby coronavirus
testing locations) in their tweets. The privacy risk reaches 100% if a user
posts three or more sensitive tweets about the pandemic. We investigate the
number of suspicious domains shared on social media during different phases of
the pandemic. Our analysis reveals an increase in the number of suspicious
domains during the lockdown compared to other lockdown phases. We observe that
IT, Search Engines, and Businesses are the top three categories that contain
suspicious domains. Our analysis reveals that adversaries' strategies to
instigate malicious activities change with the country's pandemic situation.
