KnowBe4, a provider of security awareness training and simulated phishing platform, on Tuesday issued a warning regarding the Microsoft Exchange exploit that has affected tens of thousands of accounts around the world.

Security threats from the incident, the company said, range from takeovers of servers which can result in complete environment takeovers to account impersonations to ransomware.

“Once a hacker gets into a server, they can take over every part of an organization's environment, join an existing email thread and add malicious links and attachments into a conversation,” KnowBe4 stated in a release.

“Cybersecurity attacks are targeting unpatched Microsoft Exchange servers using a new strain of ransomware called DearCry. These attacks can encrypt computer systems and aim to gather payment from users.”

Company CEO Stu Sjouwerman said the security issue has had a massive impact with far-reaching consequences: “Once a hacker gets into the system and accesses the server that controls all of the e-mail accounts, they can completely take over an environment and really wreak havoc.

“Account impersonation is incredibly dangerous because the recipient of the e-mail believes that they are speaking to the trusted party via e-mail, so they are much more likely to click on a malicious link or open an infected email attachment.”

Ransomware, added Sjouwerman, is another one of the “potential cybersecurity problems that threaten the operational capabilities of businesses that have not patched their systems yet due to this exploit. For any organization using Microsoft Exchange servers, it is recommended to patch immediately.

“Microsoft says that after the "initial compromise of unpatched on-premises Exchange Servers" ransomware is deployed on vulnerable systems, a situation reminiscent of the 2017 WannaCry outbreak. The tech giant is urging customers to apply the updates as soon as possible due to the critical nature of the security issues.”

Additional information about the hack is available on KnowBe4's company web site.