What happened
Microsoft published 'Guarding AI Memory' on June 22, 2026 — a Security Copilot-focused post breaking down how threat actors can target AI memory stores (conversation history, retrieved context, persistent memory) through prompt injection, indirect injection via retrieved documents, and memory poisoning, along with Microsoft's defensive architecture and telemetry-based detection recommendations. Companion to the June 9 AI investigation playbook for M365 Copilot and Azure AI.
Why it matters
AI memory is an emerging, under-defended attack surface: compromising what an AI remembers can persist across sessions and silently alter agent behavior at scale. Microsoft's framing establishes a threat model that security teams need for any persistent AI agent deployment.
Applicability
Security architects deploying persistent AI agents (M365 Copilot, Azure AI Foundry, any RAG-based agent) should review this guidance immediately and model memory as a new trust boundary requiring equivalent controls to other sensitive data stores.