MS Purview DLP: Web search blocking also blocks Copilot response
Hello everyone, I am currently testing a Microsoft Purview DLP policy for Microsoft 365 Copilot that is intended to prevent personal or sensitive information contained in a Copilot prompt from being used for a web search. When a user enters a prompt containing specific Sensitive Information Types (SITs), only the web search should be blocked. Copilot should still process the prompt and, if possible, provide a response without using web search or sending the detected sensitive information to the web search service. Configuration In Microsoft Purview, I only have the following actions available: Processing of prompts → Block Performing web searches → Block I tested both options separately. Behavior with “Processing prompts → Block” This works as expected: As soon as a configured SIT is detected in the prompt, processing is blocked immediately and Copilot displays a corresponding policy notification. Behavior with “Performing web searches → Block” I observe the following behavior: I send a prompt to Copilot that contains a SIT covered by the DLP policy. Copilot initially generates a normal response. In this response, Copilot indicates that the personal information was not used for the web search. However, the actual question is still answered. This response remains visible for approximately 1–2 seconds. The entire Copilot response then disappears. Instead, the following message is displayed: “Due to your organization’s policies, none of the requested files or resources are available.” The previously generated response, which was briefly visible, can no longer be accessed afterwards. Expected behavior Since I would like to use “Performing web searches → Block” in the DLP policy, I would expect that: the web search is blocked, sensitive information is not used for the web search, Copilot can still process the prompt, and the response generated by Copilot remains visible. Question Is this behavior expected when using the DLP action “Performing web searches → Block”? In particular, I would like to understand why Copilot initially generates and displays a response without using the sensitive information for the web search, but then completely removes this response a few seconds later and replaces it with the policy notification. Is it possible to configure additional actions in the DLP policy, or to select an option other than “Block”? I only have the two actions mentioned above available. I have attached the relevant screenshots. Please note that the attached screenshots are in German. Thank you in advance!Understanding Microsoft 365 Copilot Risk Surface and Mitigations
Microsoft 365 Copilot acts on the access users already have. It does not grant new permissions — it is a force multiplier that makes existing access faster and easier to discover, aggregate, and act on across Microsoft 365. That speed and accessibility can also amplify existing security and governance gaps. In environments with overshared content, excessive permissions, or inconsistent governance, users may gain faster access to sensitive information than organizations realize. It’s a shift that carries important security implications organizations should understand before scaling deployment. Customers with Microsoft 365 E5 licensing may already have access to many of the tools that can help identify and reduce Copilot-related risk, but licensing alone does not reduce exposure. What’s often missing during early Copilot deployments is a clear understanding of the risk surface itself: what data is exposed, who can access it, and through which vectors.
