services / Azure / Function App master key

The Function App master key, an admin-level credential that bypasses function-level authorization to invoke and administer all functions in the Function App runtime.

Master key grants full administrative control of the Functions runtime and enables code execution under the app's managed identity.

Microsoft.​Web/​Sites/​hostruntime/​host/​_​master/​read

Returns the admin master key as reusable credential material, enabling invocation/management of all functions and code execution as the app identity.

Risks

1. Account takeover (CRITICAL)
2. Cryptographic exfiltration (CRITICAL)
3. Lateral movement (BOOST)

Scope: CRITICAL

This privilege may grant access to sensitive data from a significant fraction of organizational functions, allow interruption of critical organizational services, or its exploit could lead to significant privilege escalation.

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