Microsoft Security Blog · May 12, 2026

Undermining the trust boundary: Investigating a stealthy intrusion through third-party compromise

Why it matters

Microsoft Incident Response investigated an attack operated through legitimate and trusted administrative mechanisms to blend seamlessly into routine operations and remain undetected demonstrating that intrusions have increasingly avoided using noisy exploits, obvious malware, or custom tooling, instead leveraging syst

My takeaway: Microsoft Incident Response investigated an attack operated through legitimate and trusted administrative mechanisms to blend seamlessly into routine operations and remain undetected demonstrating that intrusions have increasingly avoided using noisy exploits, obvious malware, or custom tooling, instead leveraging syst