Inga Beale, chief executive of Lloyd's, said: "This report gives a real sense of the scale of damage a cyber-attack could cause the global economy".
The company, which published the 56-page report in cooperation with computer security firm Cyence, said its findings also reflect how hard it is to model and understand an area in which there is so little historical data upon which to base assumptions.
The uninsured gap could be as much as $45bn for the cloud services scenario - meaning that less than a fifth (17%) of the economic losses are actually covered by insurance.
A new study from insurance firm Lloyds put the price-tag of an extreme cyber-attack at up to Dollars 53 billion worldwide.
In its report, which it has co-written with Cyence, a cybersecurity analytics platform provider, the insurer suggested that the direct economic impacts of cyber events lead to a wide range of potential economic losses.
The analysis reveals that under the mass software vulnerability attack scenario, the cyber protection gap is between $8.9 billion for a large event and $26.6 billion for an extreme event, which means that just 7% of the economic losses are covered by insurance protection. The financial and reputational cost in terms of business interruption and remediation can be substantial.
In the hypothetical cloud service attack in the Lloyd's-Cyence scenario, hackers inserted malicious code into a cloud provider's software that was created to trigger system crashes among users a year later.
The losses could come from a wide-ranging assault on their cloud service provider that causes failure for their own company, customers and suppliers, Lloyd's warns today. Just like some of the worst natural catastrophes, cyberevents can cause a severe impact on businesses and economies, trigger multiple claims and dramatically increase insurers' claims costs.
As digital technology innovations, such as the sharing economy, blockchain or the Internet of Things, are multiplying at an unprecedented pace and connecting more deeply with the physical world, cyber risks are likely to rise, according to the World Economic Forum.
The 56-page report estimated potential economic losses based on the examination of a hypothetical hacking of a cloud service provider and cyberattacks on computer operating systems run by global businesses.