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Introduction
Microsoft Graph API is a powerful tool for automating tasks in Microsoft 365 and Azure, but some endpoints restrict access via Graph PowerShell or CLI—especially in GCC environments. Security professionals like Nathan McNulty discovered a workaround: borrowing Bearer tokens from browser sessions to authenticate requests. This article explores how to leverage this technique for seamless API interactions.
Learning Objectives
- Understand how Bearer tokens work in Microsoft Graph API.
- Learn how to extract and reuse tokens from browser sessions.
- Apply this method to bypass Graph PowerShell/CLI limitations.
You Should Know
1. Extracting Bearer Tokens from Browser Sessions
When logged into the Microsoft portal, your browser stores authentication tokens. These can be extracted for API requests.
Steps to Extract a Bearer Token (Chrome/Edge DevTools)
1. Open Developer Tools (F12) in your browser.
2. Navigate to the Network tab.
- Visit a Microsoft Graph-related page (e.g., Entra Admin Center).
- Locate a request to `https://graph.microsoft.com` and check the Headers tab.
5. Copy the `Authorization: Bearer ` value.
Usage in PowerShell:
$token = "Bearer eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiIsIng1dCI6..."
Invoke-RestMethod -Uri "https://graph.microsoft.com/v1.0/users" -Headers @{Authorization = $token}
This bypasses client-based authentication restrictions.
2. Using the Token in Graph PowerShell
If Graph PowerShell fails due to endpoint restrictions, manually inject the token.
Steps to Force Token Usage
1. Extract the token as above.
2. Use it in a custom request:
$headers = @{
"Authorization" = $token
"Content-Type" = "application/json"
}
$response = Invoke-RestMethod -Method Get -Uri "https://graph.microsoft.com/beta/identity/conditionalAccess/policies" -Headers $headers
$response | ConvertTo-Json -Depth 10
3. Handling GCC & Restricted Endpoints
Government Cloud (GCC) environments often block standard Graph PowerShell auth.
Workaround for GCC Compliance
1. Log into the GCC portal (portal.cloudgov.us).
2. Extract the token as before.
3. Use it in CLI with `curl`:
curl -H "Authorization: Bearer $TOKEN" "https://graph.microsoft.us/v1.0/users"
4. Automating Token Refresh
Bearer tokens expire. Automate renewal with:
PowerShell Token Refresh Script
Check token expiry
$tokenPayload = $token.Split('.')[bash]
$decodedPayload = [System.Text.Encoding]::UTF8.GetString([System.Convert]::FromBase64String($tokenPayload)) | ConvertFrom-Json
$expiryTime = [bash]::FromFileTime($decodedPayload.exp 10000000)
if ((Get-Date) -ge $expiryTime) {
Write-Warning "Token expired. Re-authenticate."
}
5. Securing Extracted Tokens
Stolen tokens can lead to breaches. Mitigate risks with:
Best Practices for Token Security
- Never hardcode tokens in scripts.
- Use Azure Key Vault for storage:
az keyvault secret set --vault-name MyVault --name GraphToken --value $token
- Enable Conditional Access to restrict token usage.
What Undercode Say
- Key Takeaway 1: Borrowing tokens from browser sessions is a powerful workaround for Graph API limitations, especially in restricted environments like GCC.
- Key Takeaway 2: While useful, this method introduces security risks—always enforce strict token handling policies.
Analysis:
This technique highlights the flexibility (and fragility) of token-based authentication. While it solves immediate access issues, organizations must balance convenience with security. Future Graph API updates may close this loophole, so automation via secure service principals remains the gold standard.
Prediction
As Microsoft tightens Graph API security, manual token borrowing may become obsolete. Expect more granular OAuth 2.0 scopes and device-based Conditional Access policies to enforce stricter client validation. Organizations should prepare by migrating to certificate-based auth or managed identities for long-term stability.
This guide equips IT and security teams with actionable methods to bypass Graph API restrictions—responsibly. Always audit token usage and adhere to least-privilege principles.
IT/Security Reporter URL:
Reported By: Nathanmcnulty Pro – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
