In an op-ed published by the American website Fortune, Ryan Kalember, executive vice-president of Cyber Security Strategy at Proofpoint, said Microsoft had recently announced it would spend US$20 billion (A$28 billion) on better cyber security tools over the next five years, a step up from the US$1 billion it had spent annually since 2015.

"This is yet another step in Microsoft’s quest to position itself as the global leader in cyber security," he said. "But while this may appear a noble endeavour, all is not quite as it seems. Microsoft technology is a significant contributing factor in increasingly devastating cyber attacks."

Kalember said Microsoft's failure to shore up known vulnerabilities was believed to have exacerbated the recent SolarWinds hack.

"Meanwhile, its cyber security arm has seen 40% growth year on year, with revenues reaching US$10 billion. This makes for a rather uncomfortable dichotomy. Far from a cyber security saviour, is Microsoft effectively setting the house on fire and leaving organisations with the bill for putting it out?" he asked.

Kalember pointed out that email was the top entry point for cyber threats and malicious messages sent from Office 365 targeted about 60 million users in 2020.

"...this puts everyone at risk, not just Microsoft customers. Delivery from a trusted entity is critical to successful ransomware, phishing, and business email compromise attacks," he said.

"With millions of messages sent from gold-plated domains like Outlook.com, many are sure to get through. Cyber security Twitter was recently aflame when ransomware groups sent out phishing attacks from compromised Exchange servers, pointing to malware hosted on OneDrive. Some of that malware stayed there for months before being taken down."

These vulnerabilities and platform abuse, Kalember claimed, were just the beginning. "Microsoft has also made many catastrophic architectural decisions. The design of Active Directory, Office macros, PowerShell, and other tools has enabled successive generations of threat actors to compromise entire environments undetected. This is one of the primary reasons why ransomware attacks spread from single machines to entire organisations unchecked.

"Now, many of these mistakes are being repeated in the cloud. We only need look at the horribly insecure default configuration of Office 365 for evidence of that."

In its defence, Kalember said it was not Microsoft's intention to become a leading contributor to security risk.

He contrasted the company's approach to software with that of Google and Apple. "If the company was moving slower to ship more secure code, discontinuing old features (like Apple), or trying to get its massive customer base to a great security baseline faster (like Google), it could do amazing things for the security community. But it’s not."

And he accused the Redmond giant of profiting from vulnerabilities and exploitable configurations. "...with one hand, the company ships vulnerabilities and hosts malware, and with the other, it charges to 'protect' users from those same vulnerabilities and threats.

"Add in the world’s most extensive incident response practice, and Microsoft is the arsonist, the fire department, and the building inspector all rolled into one."

On the plus side, Kalember said numerous companies were now looking beyond Microsoft to protect users and environments.

"Most security leaders are reluctant to put all their eggs in a Microsoft basket, but all IT professionals should both expect and demand that all their vendors, even the big ones, mitigate more security risk than they create," he added.