An Unreasonable Azure AD Sign-in Frequency Creates a Barrier to Productivity
I had an unpleasant surprise this week when the security team for one of the companies where I have a guest account decided to improve tenant security. I strongly support any effort to improve tenant security, especially when the effort means better use of multi-factor authentication. It’s a topic I’ll cover during the TEC Europe 2023 tour in London, Paris, and Frankfurt in April. Registration for those events is now open.
It’s always important to take a pragmatic and practical view of security and not to implement anything that has a significant impact on user productivity. All change can impact users, but most of the time people learn to live with change and it’s not disruptive. Unfortunately, deciding to increase the user sign-in frequency for Azure AD accounts can be extraordinarily disruptive if you go too far.
Azure AD sign-in frequency is the period before a user must sign in again when attempting to access a resource, like opening a SharePoint Online document, creating a message with OWA, or accessing a Teams channel. By default, Azure AD uses a rolling 90-day window for its sign-in frequency. In other words, once you successfully sign-into a tenant, Azure AD won’t ask you to sign-in again for another 90 days.
Revoking User Account Access
Ninety days sounds like a long time, and it is. But this period needs to be viewed through the prism of how Azure AD and Microsoft 365 applications work. For example, in early 2022, Microsoft enabled Continuous Access Evaluation (CAE) for all tenants. CAE is a mechanism that allows Azure AD to notify applications of a critical change in the directory, such as an updated password. Applications that understand CAE, like SharePoint Online, revoke existing access for the account to require the user to reauthenticate.
The Microsoft 365 admin center also includes an option to sign users out of all current sessions (Figure 1) to force them to reauthenticate.
Figure 1: Forcing a user to sign out and reauthenticate
Of course, you might want to do more than sign a user out. In some cases, like employee departures, you might want to block future sign-ins. This is an operation that’s easily scripted with PowerShell. For example, this code:
Retrieves the identifier for an Azure AD user account.
Disables the account.
Sets a new password.
Revokes all refresh tokens.
$UserId = (Get-MgUser -UserId Lotte.Vettler@Office365itpros.com).Id
# Disable the account
Update-MgUser-UserId $UserId -AccountEnabled:$False
# Set a new password
$NewPassword = @{}
$NewPassword["Password"]= "!DoneAndDusted?"
$NewPassword["ForceChangePasswordNextSignIn"] = $True
Update-MgUser -UserId $UserId -PasswordProfile $NewPassword -AccountEnabled:$True
# Revoke refresh tokens
$Status = Invoke-MgInvalidateUserRefreshToken -UserId $UserId
It might take a little time for the full block to be effective because tokens must expire, and clients recognize the need for reauthentication, but it will happen.
How Conditional Access Can Make Guest Accounts Miserable
The reason I had a problem was that the security team updated the conditional access policies for guest users to enforce a 60-minute sign-in frequency (Figure 2). This change had a horrible effect. Guests switching to the tenant with Teams inevitably resulted in an MFA challenge. Opening a document stored in SharePoint Online or OneDrive for Business in that tenant brought an MFA challenge. My day was filled with MFA challenges, except when sending email to people in the tenant to complain about the new policy. Email isn’t affected by conditional access policies.
Figure 2: Setting the sign-in frequency in an Azure AD conditional access policy
As Microsoft notes in their documentation, “Based on customer feedback, sign-in frequency will apply for MFA as well.” They understate the matter. Sign-in frequency does apply for MFA too.
I understand the motivation on the part of the security team. Forcing people to reauthenticate before they can access resources is a good thing. Using MFA is a good thing. Forcing MFA challenges every hour must be a brilliant change to make.
Only it isn’t. As an external person working with another company, the change made my productivity much worse, and I doubt that it added one iota to the overall security effectiveness of the tenant. The tenant did not use number matching and additional context for MFA challenges, so the constant MFA challenges were a great example of how user fatigue creeps in as I clicked and clicked again to say “yes, it’s me.” System-preferred authentication wasn’t used either, so while I used the Authenticator app, other guests might use relatively insecure SMS challenge/response.
Overall, the change made it unpleasant to work with the tenant and that’s bad. A one-hour sign-in frequency is just too rigid and strict. I don’t know of any other tenant (where I am a guest) that uses such a short frequency. Most tenants I know of use the 90-day default. Some use 7 days. The most security-conscious (before now) uses a 1-day frequency.
No Best Answer for All Tenants
In truth, I don’t know the best user sign-in frequency to use for either tenant or guest accounts. It all depends on the security posture that an organization wants to assume. But I can say that most tenants would be better off making sure that all accounts use MFA and eliminating the use of the less secure authentication methods before reducing the sign-in frequency. If you’re concerned about guest hygiene (in this case, how secure a guest account is), have a different and more restrictive conditional access policy for guest access while remembering the need to get work done through Azure B2B collaboration. And review guest accounts annually to remove unwanted and obsolete crud.
To me, bringing users along on the journey to better security is a better tactic than ramming heightened security down their throats. It’s always been that way.
So much change, all the time. It’s a challenge to stay abreast of all the updates Microsoft makes across Office 365. Subscribe to the Office 365 for IT Pros eBook to receive monthly insights into what happens, why it happens, and what new features and capabilities mean for your tenant.
{"id":null,"mode":"button","open_style":"in_modal","currency_code":"EUR","currency_symbol":"\u20ac","currency_type":"decimal","blank_flag_url":"https:\/\/office365itpros.com\/wp-content\/plugins\/tip-jar-wp\/\/assets\/images\/flags\/blank.gif","flag_sprite_url":"https:\/\/office365itpros.com\/wp-content\/plugins\/tip-jar-wp\/\/assets\/images\/flags\/flags.png","default_amount":100,"top_media_type":"featured_image","featured_image_url":"https:\/\/office365itpros.com\/wp-content\/uploads\/2022\/11\/cover-141x200.jpg","featured_embed":"","header_media":null,"file_download_attachment_data":null,"recurring_options_enabled":true,"recurring_options":{"never":{"selected":true,"after_output":"One time only"},"weekly":{"selected":false,"after_output":"Every week"},"monthly":{"selected":false,"after_output":"Every month"},"yearly":{"selected":false,"after_output":"Every year"}},"strings":{"current_user_email":"","current_user_name":"","link_text":"Virtual Tip Jar","complete_payment_button_error_text":"Check info and try again","payment_verb":"Pay","payment_request_label":"Office 365 for IT Pros","form_has_an_error":"Please check and fix the errors above","general_server_error":"Something isn't working right at the moment. Please try again.","form_title":"Office 365 for IT Pros","form_subtitle":null,"currency_search_text":"Country or Currency here","other_payment_option":"Other payment option","manage_payments_button_text":"Manage your payments","thank_you_message":"Thank you for supporting the work of Office 365 for IT Pros!","payment_confirmation_title":"Office 365 for IT Pros","receipt_title":"Your Receipt","print_receipt":"Print Receipt","email_receipt":"Email Receipt","email_receipt_sending":"Sending receipt...","email_receipt_success":"Email receipt successfully sent","email_receipt_failed":"Email receipt failed to send. Please try again.","receipt_payee":"Paid to","receipt_statement_descriptor":"This will show up on your statement as","receipt_date":"Date","receipt_transaction_id":"Transaction ID","receipt_transaction_amount":"Amount","refund_payer":"Refund from","login":"Log in to manage your payments","manage_payments":"Manage Payments","transactions_title":"Your Transactions","transaction_title":"Transaction Receipt","transaction_period":"Plan Period","arrangements_title":"Your Plans","arrangement_title":"Manage Plan","arrangement_details":"Plan Details","arrangement_id_title":"Plan ID","arrangement_payment_method_title":"Payment Method","arrangement_amount_title":"Plan Amount","arrangement_renewal_title":"Next renewal date","arrangement_action_cancel":"Cancel Plan","arrangement_action_cant_cancel":"Cancelling is currently not available.","arrangement_action_cancel_double":"Are you sure you'd like to cancel?","arrangement_cancelling":"Cancelling Plan...","arrangement_cancelled":"Plan Cancelled","arrangement_failed_to_cancel":"Failed to cancel plan","back_to_plans":"\u2190 Back to Plans","update_payment_method_verb":"Update","sca_auth_description":"Your have a pending renewal payment which requires authorization.","sca_auth_verb":"Authorize renewal payment","sca_authing_verb":"Authorizing payment","sca_authed_verb":"Payment successfully authorized!","sca_auth_failed":"Unable to authorize! Please try again.","login_button_text":"Log in","login_form_has_an_error":"Please check and fix the errors above","uppercase_search":"Search","lowercase_search":"search","uppercase_page":"Page","lowercase_page":"page","uppercase_items":"Items","lowercase_items":"items","uppercase_per":"Per","lowercase_per":"per","uppercase_of":"Of","lowercase_of":"of","back":"Back to plans","zip_code_placeholder":"Zip\/Postal Code","download_file_button_text":"Download File","input_field_instructions":{"tip_amount":{"placeholder_text":"How much would you like to tip?","initial":{"instruction_type":"normal","instruction_message":"How much would you like to tip? Choose any currency."},"empty":{"instruction_type":"error","instruction_message":"How much would you like to tip? Choose any currency."},"invalid_curency":{"instruction_type":"error","instruction_message":"Please choose a valid currency."}},"recurring":{"placeholder_text":"Recurring","initial":{"instruction_type":"normal","instruction_message":"How often would you like to give this?"},"success":{"instruction_type":"success","instruction_message":"How often would you like to give this?"},"empty":{"instruction_type":"error","instruction_message":"How often would you like to give this?"}},"name":{"placeholder_text":"Name on Credit Card","initial":{"instruction_type":"normal","instruction_message":"Enter the name on your card."},"success":{"instruction_type":"success","instruction_message":"Enter the name on your card."},"empty":{"instruction_type":"error","instruction_message":"Please enter the name on your card."}},"privacy_policy":{"terms_title":"Terms and conditions","terms_body":null,"terms_show_text":"View Terms","terms_hide_text":"Hide Terms","initial":{"instruction_type":"normal","instruction_message":"I agree to the terms."},"unchecked":{"instruction_type":"error","instruction_message":"Please agree to the terms."},"checked":{"instruction_type":"success","instruction_message":"I agree to the terms."}},"email":{"placeholder_text":"Your email address","initial":{"instruction_type":"normal","instruction_message":"Enter your email address"},"success":{"instruction_type":"success","instruction_message":"Enter your email address"},"blank":{"instruction_type":"error","instruction_message":"Enter your email address"},"not_an_email_address":{"instruction_type":"error","instruction_message":"Make sure you have entered a valid email address"}},"note_with_tip":{"placeholder_text":"Your note here...","initial":{"instruction_type":"normal","instruction_message":"Attach a note to your tip (optional)"},"empty":{"instruction_type":"normal","instruction_message":"Attach a note to your tip (optional)"},"not_empty_initial":{"instruction_type":"normal","instruction_message":"Attach a note to your tip (optional)"},"saving":{"instruction_type":"normal","instruction_message":"Saving note..."},"success":{"instruction_type":"success","instruction_message":"Note successfully saved!"},"error":{"instruction_type":"error","instruction_message":"Unable to save note note at this time. Please try again."}},"email_for_login_code":{"placeholder_text":"Your email address","initial":{"instruction_type":"normal","instruction_message":"Enter your email to log in."},"success":{"instruction_type":"success","instruction_message":"Enter your email to log in."},"blank":{"instruction_type":"error","instruction_message":"Enter your email to log in."},"empty":{"instruction_type":"error","instruction_message":"Enter your email to log in."}},"login_code":{"initial":{"instruction_type":"normal","instruction_message":"Check your email and enter the login code."},"success":{"instruction_type":"success","instruction_message":"Check your email and enter the login code."},"blank":{"instruction_type":"error","instruction_message":"Check your email and enter the login code."},"empty":{"instruction_type":"error","instruction_message":"Check your email and enter the login code."}},"stripe_all_in_one":{"initial":{"instruction_type":"normal","instruction_message":"Enter your credit card details here."},"empty":{"instruction_type":"error","instruction_message":"Enter your credit card details here."},"success":{"instruction_type":"normal","instruction_message":"Enter your credit card details here."},"invalid_number":{"instruction_type":"error","instruction_message":"The card number is not a valid credit card number."},"invalid_expiry_month":{"instruction_type":"error","instruction_message":"The card's expiration month is invalid."},"invalid_expiry_year":{"instruction_type":"error","instruction_message":"The card's expiration year is invalid."},"invalid_cvc":{"instruction_type":"error","instruction_message":"The card's security code is invalid."},"incorrect_number":{"instruction_type":"error","instruction_message":"The card number is incorrect."},"incomplete_number":{"instruction_type":"error","instruction_message":"The card number is incomplete."},"incomplete_cvc":{"instruction_type":"error","instruction_message":"The card's security code is incomplete."},"incomplete_expiry":{"instruction_type":"error","instruction_message":"The card's expiration date is incomplete."},"incomplete_zip":{"instruction_type":"error","instruction_message":"The card's zip code is incomplete."},"expired_card":{"instruction_type":"error","instruction_message":"The card has expired."},"incorrect_cvc":{"instruction_type":"error","instruction_message":"The card's security code is incorrect."},"incorrect_zip":{"instruction_type":"error","instruction_message":"The card's zip code failed validation."},"invalid_expiry_year_past":{"instruction_type":"error","instruction_message":"The card's expiration year is in the past"},"card_declined":{"instruction_type":"error","instruction_message":"The card was declined."},"missing":{"instruction_type":"error","instruction_message":"There is no card on a customer that is being charged."},"processing_error":{"instruction_type":"error","instruction_message":"An error occurred while processing the card."},"invalid_request_error":{"instruction_type":"error","instruction_message":"Unable to process this payment, please try again or use alternative method."},"invalid_sofort_country":{"instruction_type":"error","instruction_message":"The billing country is not accepted by SOFORT. Please try another country."}}}},"fetched_oembed_html":false}
Nicely explained Tony and a point well made. Getting that balance between security and usability is key.