purview-copilot-oversharing

purview-copilot-oversharing is a skill for Claude Code, Codex from vinayaklatthe/microsoft-security-skills. It costs 187 tokens per session (1,394 once invoked), scanned A, original, MIT.

Guidance for finding and reducing overly broad access to files in SharePoint, OneDrive, and Teams before Microsoft 365 Copilot can surface them. It covers permissions, sensitivity labels, restricted sites, and data-loss prevention controls.

In plain words
What is it for?
Use it to review broad sharing, protect sensitive content, exclude sites from Copilot search, and apply rules that prevent labelled content from being used by Copilot.
Why use it?
Microsoft 365 Copilot follows existing permissions, so incorrectly shared content may appear to people who should not see it. This helps reduce that exposure during a Copilot rollout.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to review broad sharing, protect sensitive content, exclude sites from Copilot search, and apply rules that prevent labelled content from being used by Copilot.

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Install with agentmods
npx agentmods add skills/vinayaklatthe/microsoft-security-skills/purview-copilot-oversharing
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add vinayaklatthe/microsoft-security-skills --skill purview-copilot-oversharing
Clone the repo
git clone --depth 1 https://github.com/vinayaklatthe/microsoft-security-skills

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for purview-copilot-oversharing

README.md
[![agentmods](https://agentmods.dev/badge/skills/vinayaklatthe/microsoft-security-skills/purview-copilot-oversharing/github.svg)](https://agentmods.dev/skills/vinayaklatthe/microsoft-security-skills/purview-copilot-oversharing)
Your own site
<a href="https://agentmods.dev/skills/vinayaklatthe/microsoft-security-skills/purview-copilot-oversharing"><img src="https://agentmods.dev/badge/skills/vinayaklatthe/microsoft-security-skills/purview-copilot-oversharing/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for purview-copilot-oversharing

Your own site · 80×15
<a href="https://agentmods.dev/skills/vinayaklatthe/microsoft-security-skills/purview-copilot-oversharing"><img src="https://agentmods.dev/badge/skills/vinayaklatthe/microsoft-security-skills/purview-copilot-oversharing.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 187 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,394 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00187 $0.01394
Opus 5 $0.00093 $0.00697
Sonnet 5 $0.00037 $0.00279
Haiku 4.5 $0.00019 $0.00139

Measured 9d ago against content hash 3d372bfb25f9, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

purview-copilot-oversharing scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 9d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/purview-copilot-oversharing/SKILL.md · 96 lines

How it starts

The opening of the file, as written. The whole thing — 96 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Microsoft 365 Copilot Oversharing Controls

Microsoft 365 Copilot honours existing permissions - so if content is overshared, Copilot can surface it to users who technically have access but shouldn't. This skill covers reducing that blast radius before and during Copilot rollout using SharePoint Advanced Management, sensitivity labels, restricted content discovery, and DLP for Copilot.

When to use

Preparing a tenant for Microsoft 365 Copilot and continuously controlling what Copilot can reach across SharePoint, OneDrive, and Teams.

Do not use this skill to monitor sensitive data in prompts (use purview-dspm-ai) or to design a broader DLP program (use purview-dlp-policy).

Pick the right oversharing lever

Symptom Lever
"Everyone except external users" (EEEU) on too many sites SAM data access governance report + permission cleanup
Sensitive content in broadly shared sites Sensitivity labels (encrypt) + container labels for sites
Site shows up in Copilot results when it shouldn't Restricted content discovery (RCD) on the site
Labelled content should be excluded from Copilot grounding DLP for Microsoft 365 Copilot
Sharing links sprawl SAM sharing link report + cleanup policies

Rule of thumb: assess (DAG report) -> classify (labels) -> restrict (RCD, link policy) -> exclude (DLP for Copilot) -> govern (site lifecycle). Skipping the assess step is the most common failure.

Approach

  1. Assess - Use SharePoint Advanced Management (SAM) data access governance reports to find oversharing: "everyone/EEEU" access, broadly shared sites, sharing links, and permissioned but sensitive content. Verify: DAG report identifies top-N risky sites with owners.
  2. Engage site owners - Notify owners of risky sites with the remediation expected; do not remediate centrally without owner context. Verify: owner remediation tickets/issues opened with deadline.
  3. Classify & label - Apply sensitivity labels to sensitive content; container labels for sites; labels can encrypt and restrict, and Copilot respects label permissions. Verify: top-tier label encrypts and Copilot cannot surface the file to unauthorised test user.
  4. Restrict - Use restricted access control / restricted content discovery (RCD) on sensitive sites, tighten "everyone except external users" grants, and clean up sharing links. Verify: RCD-flagged site no longer appears in test user's Copilot answers.
  5. Apply DLP for Copilot - Use DLP for Microsoft 365 Copilot to exclude labelled content from Copilot processing where required. Verify: a test prompt referencing labelled content is excluded or warned.
  6. Govern lifecycle - Apply site lifecycle/access reviews to prevent regression; set inactive site policies in SAM. Verify: inactive sites archived or owners re-attested per cadence.
  7. Monitor with DSPM for AI - Continuously surface unlabelled sensitive files Copilot can access; loop back to label + restrict. Verify: weekly DSPM for AI report shrinks unlabelled-sensitive count.

Read the full file on GitHub · 96 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 9d ago First seen · 96 lines · 187 tokens per session scan A 3d372bfb25f9

Subscribe to this mod's changes

purview-copilot-oversharing is a skill published in the GitHub repository vinayaklatthe/microsoft-security-skills (173 stars, last pushed 2mo ago), licensed MIT. It adds 187 tokens to every session and 1,394 once invoked, about $0.0009 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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