WARNING: New Unpatched Microsoft Exchange Zero-Day Under Active Exploitation

Security researchers are warning of previously undisclosed flaws in fully patched Microsoft Exchange servers being exploited by malicious actors in real-world attacks to achieve remote code execution on affected systems.

“We detected webshells, mostly obfuscated, being dropped to Exchange servers,” the company noted.

“Using the user-agent, we detected that the attacker uses Antsword, an active Chinese-based open source cross-platform website administration tool that supports web shell management.”

Html Exchange Server vulnerabilities, with GTSC noting that the targeted servers had already been patched against the flaws that came to light in March 2021.

It’s worth noting that the China Chopper web shell was also deployed by Hafnium, a suspected state-sponsored group operating out of China, when the ProxyShell vulnerabilities were subjected to widespread exploitation last year.

“If you don’t run Microsoft Exchange on premise, and don’t have Outlook Web App facing the internet, you are not impacted,” Beaumont said.

Share this article on social media:

Subscribe to Our Newsletter!
Stay on top of cybersecurity risks, evolving threats and industry news.

The Latest Cybersecurity News

From major cyberattacks, newly discovered critical vulnerabilities to recommended best practices, read it here first:

Tell us about your needs.
Get an answer the same business day.

Tell us about your needs.
Get an answer the same business day.

Fill out the form below and get an answer from our experts within 1 business day.

Got an urgent request? Call us at 1-877-805-7475 or Book a meeting.

PCI-DSS

What happens next:

  • We reach out to learn about your objectives
  • We work together to define your project's scope
  • You get an all-inclusive, no engagement proposal

This field is for validation purposes and should be left unchanged.
Scroll to Top

BOOK A MEETING

Enter Your
Corporate Email

This site is registered on wpml.org as a development site.