Fancy Bear, also known as APT28 and Forest Blizzard, has been targeting a Microsoft Exchange flaw (CVE-2023-23397) against targets in Poland.
Microsoft released patches for 57 vulnerabilities in November's Patch Tuesday update, including three flaws that have been actively exploited.
Microsoft warned that these attacks are “particularly high risk” for impacted organizations.
The global campaign, which occurred between July and September, mostly targeted organizations in the Americas region.
The two important-severity flaws are publicly known and are part of Microsoft’s regularly scheduled Patch Tuesday releases, which overall included more than 100 fixes.