External Sharing Is Not a Feature | It’s a Risk Decision™ | RAHSI™ Collaboration Risk Posture (RCRP™)

What RCRP™ is trying to do ## 1. External sharing as a per-zone risk decision ## 2. Guest access bound to purpose, sensitivity, and time ## 3. Link types aligned with Zero Trust + CVE reality ## 4. Partner extranets and data rooms as lifecycle-bound surfaces ## 5. Security, risk, and compliance get posture, blast radius, and cleanup ## Why this is pro-Microsoft, not anti-Microsoft ## If this sounds like your tenant… There’s a reality in Microsoft 365 we don’t often say out loud: External sharing is not just a feature – it’s a live risk surface. Every time someone clicks: …we aren’t just “collaborating”. We’re quietly creating a new security boundary on top of SharePoint Online, OneDrive, and Teams. Individually, those decisions feel harmless. At scale, in real Azure + Microsoft 365 estates, they become something your Entra ID, Purview, and Defender teams can’t treat as background noise anymore. That’s the problem I’ve tried to name and structure with: External Sharing Is Not a Feature | It’s a Risk Decision™ | RAHSI™ Collaboration Risk Posture (RCRP™) This is not a criticism of Microsoft. The platform gives us an incredible toolkit: SharePoint, OneDrive, Teams, Entra ID, Microsoft Purview, Microsoft Defender, Graph, Power Automate, and now Copilot. RCRP™ is my attempt to add an opinionated, engineering-grade risk posture on top of that stack – something Azure/M365 admins, architects, and CISOs can actually run in a real tenant. Instead of treating external sharing as a single tenant toggle, RCRP™ asks us to design collaboration zones and make the risk decision explicit for each one. Concretely, RCRP™ pushes towards: Define collaboration zones like: “Guest account + one big group = access to half the tenant, forever.” RCRP™ patterns bind guests to: When the purpose ends, the access ends. Automatically. Site owners clicking “Share” in the UI shouldn’t be the final word on risk. RCRP™ treats link types as part of your Zero Trust architecture: “We’ll delete that partner site later.” RCRP™ models partner and B2B collab sites as first-class lifecycle objects: Most security teams can tell you where the identities are. They struggle more with where the collaboration surfaces are. RCRP™ tries to give them: I’m genuinely grateful for the Microsoft 365 + Azure ecosystem: RAHSI™ Collaboration Risk Posture (RCRP™) is my way of using that stack with more discipline and intent: If you’re looking at: …then this work is for you. I’ve written up the model, patterns, and concrete examples here: Full article: https://www.aakashrahsi.online/post/rahsicollaborationriskposture I’d love to hear from Microsoft 365 admins, architects, and security engineers who are wrestling with this in real tenants – especially if you’re already deep into Entra, Purview, and Defender and still feel like external collaboration is one step ahead of your current controls. Templates let you quickly answer FAQs or store snippets for re-use. Are you sure you want to hide this comment? It will become hidden in your post, but will still be visible via the comment's permalink. Hide child comments as well For further actions, you may consider blocking this person and/or reporting abuse - “Anyone with the link can view” - “Just add this guest for the project” - “We’ll shut down that partner extranet later” - Clinical vs research vs vendor vs JV vs NOC vs KYC vs FOI vs board packs - Each with its own posture, not just “external sharing: on”. - CLINICAL-EXT-ZONE - VENDOR-ZONE - JV-DATAROOM-ZONE - NOC-EXT-ZONE - Who can be invited (which domains, which identities)? - What data classification levels are allowed? - Which link types are never valid here? - How long can external access live before it must be reviewed or removed? - A business purpose (case, project, contract, campaign, grant) - A data sensitivity profile - A time window (mandate, contract term, audit cycle, semester) - “Anyone” links are either blocked or tightly constrained by zone - “Specific people” links become the norm for high-risk areas - Sharing baselines move with CVE advisories and security guidance, not with convenience - Create → Active → Read-only → Archived → Decommissioned - Clear patterns for: Locking access Archiving content Removing guests and links Proving it all happened, if a regulator asks - Locking access - Archiving content - Removing guests and links - Proving it all happened, if a regulator asks - Locking access - Archiving content - Removing guests and links - Proving it all happened, if a regulator asks - A map of zones and their risk posture - The blast radius of each (who, where, what data) - Automatable cleanup patterns when something needs to be tightened quickly - Entra ID for identity and B2B - Purview for classification and governance - Defender for threat detection - SharePoint, OneDrive, Teams for collaboration - Graph, Power Automate, Azure Functions and friends for automation - Less “click Share and hope” - More “this is a controlled risk surface we understand, monitor, and can explain to a regulator or the board.” - Old partner sites no one owns anymore - Guests that still sign in years after projects ended - “Temporary” links that somehow became permanent - A growing unease in your security team about where data actually flows