He went on, though, to emphasize that the attack had demonstrated the “degree to which cybersecurity has become a shared responsibility between tech companies and customers,” the latter of whom must update their systems if they want to be protected. He also pointed his finger at intelligence services, since the latest vulnerability appeared to have been leaked from the National Security Agency.

On Monday, a Microsoft spokesman declined to comment beyond Mr. Smith’s post.

To prepare for fallout with customers, Judson Althoff, a Microsoft executive vice president, sent an email to the company’s field sales team on Sunday encouraging them to be supportive of businesses targeted by the attack, or even those who were simply aware of it.

“Our key direction to you is to remember that we are in this with our customers — we are trusted advisers, counselors, and suppliers to them,” he wrote. “More than technical guidance, I want you to make sure you are spending the time needed to understand the concerns they have and that they know we are here to help.”

While Microsoft’s reputation has suffered in the past because of security problems, the company’s stock is barely down from the close of trading on Thursday, just before reports of the ransomware.

“People have extremely short memories when it comes to this,” said Jan Dawson, an analyst with Jackdaw Research. “I think, realistically, people will move on pretty quickly.”