Device Code Flow in Entra ID (formerly Azure AD) is an OAuth 2.0 authentication method that allows users to sign in on input-constrained devices. However, attackers can abuse this flow in phishing or brute-force attacks. Restricting it enhances security.
Read the full guide here: janbakker.tech
You Should Know:
- Disable Device Code Flow in Entra ID (Azure AD)
To restrict Device Code Flow, use PowerShell:
Connect to Azure AD Connect-AzureAD Disable Device Code Flow for all applications Set-AzureADMSAuthorizationPolicy -Id "authorizationPolicy" -DefaultDeviceEnrollmentRestrictions "AllDevices" -AllowedToDeviceJoin $false
2. Enable Conditional Access Policies
Create a Conditional Access policy to block Device Code Flow:
- Go to Azure Portal → Azure AD → Security → Conditional Access.
2. Create a new policy:
- Users and groups: Select target users.
- Cloud apps: Choose All cloud apps.
- Conditions → Client apps: Enable Mobile apps and desktop clients.
- Grant: Select Block access.
3. Monitor Suspicious Device Code Requests
Use Microsoft Defender for Identity to detect anomalies:
Check sign-in logs for Device Code Flow usage
Get-AzureADAuditSignInLogs -Filter "tokenIssuerType eq 'AzureAD'" | Where-Object { $_.DeviceDetail -like "DeviceCode" }
4. Restrict Device Registration
Prevent unauthorized devices from joining:
Disable device registration for non-admin users Set-MsolCompanySettings -UsersPermissionToCreateGroupsEnabled $false
5. Use Microsoft Graph API for Automation
Automate Device Code Flow restrictions via Graph API:
List all Conditional Access policies curl -X GET "https://graph.microsoft.com/v1.0/identity/conditionalAccess/policies" -H "Authorization: Bearer <ACCESS_TOKEN>"
What Undercode Say:
Restricting Device Code Flow is crucial to prevent OAuth-based attacks. Combine Conditional Access, PowerShell automation, and monitoring to secure Entra ID.
Additional Security Commands:
- Check Azure AD risky sign-ins:
Get-AzureADRiskyUser -All $true
- Block legacy authentication:
Set-AzureADPolicy -Definition @('{"TokenLifetimePolicy":{"Version":1,"AccessTokenLifetime":"08:00:00"}}') - Audit device registrations:
azure ad audit logs --query "ActivityDateTime desc" --filter "Category eq 'DeviceManagement'"
Expected Output:
A secure Entra ID environment with restricted Device Code Flow, enforced Conditional Access, and continuous monitoring.
Prediction:
As attackers increasingly exploit OAuth flows, Microsoft will likely enforce stricter Device Code Flow restrictions by default in future Entra ID updates.
References:
Reported By: Jan Bakker – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
