05:27 AM EDT, 09/11/2025 (MT Newswires) -- (Updates with Microsoft's ( MSFT ) response in the third and fourth paragraphs.)

A US senator is calling on the Federal Trade Commission to investigate Microsoft ( MSFT ) in connection with a 2024 ransomware attack on health system operator Ascension, Bloomberg News reported Wednesday, citing a letter from the lawmaker.

In the letter, Sen. Ron Wyden stated that hackers exploited the insecure RC4 encryption technology used by default on Microsoft Windows computers, according to the report.

"RC4 is an old standard, and we discourage its use both in how we engineer our software and in our documentation to customers -- which is why it makes up less than .1% of our traffic," a Microsoft ( MSFT ) spokesperson said in a statement e-mailed to MT Newswires.

"However, disabling its use completely would break many customer systems," the spokesperson said. "For this reason, we're on a path to gradually reduce the extent to which customers can use it, while providing strong warnings against it and advice for using it in the safest ways possible. We have it on our roadmap to ultimately disable its use."

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