https://krebsonsecurity.com/2021/03/at-least-30000-u-s-organizations-newly-hacked-via-holes-in-microsofts-email-software/
At least 30,000 organizations across the United States — including a significant number of small businesses, towns, cities and local governments — have over the past few days been hacked by an unusually aggressive Chinese cyber espionage unit that’s focused on stealing email from victim organizations, multiple sources tell KrebsOnSecurity. The espionage group is exploiting four newly-discovered flaws in Microsoft Exchange Server email software, and has seeded hundreds of thousands of victim organizations worldwide with tools that give the attackers total, remote control over affected systems.
By all accounts, rooting out these intruders is going to require an unprecedented and urgent nationwide clean-up effort. Adair and others say they’re worried that the longer it takes for victims to remove the backdoors, the more likely it is that the intruders will follow up by installing additional backdoors, and perhaps broadening the attack to include other portions of the victim’s network infrastructure.
KrebsOnSecurity has seen portions of a victim list compiled by running such a tool, and it is not a pretty picture. The backdoor web shell is verifiably present on the networks of thousands of U.S. organizations, including banks, credit unions, non-profits, telecommunications providers, public utilities and police, fire and rescue units.
“It’s police departments, hospitals, tons of city and state governments and credit unions,” said one source who’s working closely with federal officials on the matter. “Just about everyone who’s running self-hosted Outlook Web Access and wasn’t patched as of a few days ago got hit with a zero-day attack.”