Insurers are struggling to estimate their potential exposure to cyber-related losses amid mounting cyber risks and interest in cyber insurance.
A lack of historical data on which insurers can base assumptions is a key challenge.
"Because cyber is virtual, it is such a difficult task to understand how it will accumulate in a big event," Lloyd's of London Chief Executive Inga Beale told Reuters.
Economic costs in the hypothetical cloud provider attack dwarf the $8 billion global cost of the "WannaCry" ransomware attack in May, which spread to more than 100 countries, according to Cyence.
Economic costs typically include business interruptions and computer repairs.
The Lloyd's report follows a U.S. government warning to industrial firms about a hacking campaign targeting the nuclear and energy sectors.
In June, an attack of a virus dubbed "NotPetya" spread from infections in Ukraine to businesses around the globe. It encrypted data on infected machines, rendering them inoperable and disrupted activity at ports, law firms and factories.
"NotPetya" caused $850 million in economic costs, Cyence said.