BOSTON (AP) — Victims of a massive global hack of Microsoft email server software are hustling to shore up infected systems and otherwise diminish chances that intruders might extend their foothold and steal data or hobble their networks.

The White House calls the situation an active threat. Cybersecurity experts estimate victims in the tens of thousands.

And while the hack doesn’t pose the kind of national security threat as the SolarWinds attack, which the Biden administration blames on Russian intelligence officers and which was more sophisticated, it can be an existential threat for victims hit before they had a chance to patch who have hackers lingering in their systems.

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