Microsoft Security Division

Rule Changes

Leading enterprise-wide security transformation

On January 12, 2026, millions of Teams users woke up to find their security settings had changed overnight. Microsoft activated weaponizable file blocking, malicious URL detection, and phishing protections across every organization still using default configurations—no IT administrator approval required. Days earlier, the company had quietly expanded Zero-Hour Auto Purge malware removal to all Defender for Office 365 Plan 1 customers, creating a one-two punch of automated threat protection. The moves mark the sharpest turn yet in Microsoft's $34 billion bet that 'secure by default' can repair its battered reputation after Russian and Chinese hackers ransacked its networks in 2023.

Updated Jan 14