{"id":13847,"date":"2025-11-19T02:01:13","date_gmt":"2025-11-18T17:01:13","guid":{"rendered":"https:\/\/m365jp.net\/?p=13847"},"modified":"2025-11-19T02:06:07","modified_gmt":"2025-11-18T17:06:07","slug":"mc1187679-microsoft-teams-protection-against-tenant-owned-domain-impersonation-in-teams-chat","status":"publish","type":"post","link":"https:\/\/m365jp.net\/index.php\/2025-11-19-mc1187679-microsoft-teams-protection-against-tenant-owned-domain-impersonation-in-teams-chat","title":{"rendered":"MC1187679 | Microsoft Teams: Protection against tenant-owned domain impersonation in Teams chat"},"content":{"rendered":"<div class=\"postie-post\">\n<div>\n<hr>\n<table id=\"section\">\n<tbody>\n<tr>\n<th width=\"95%\">MC1187679 | Microsoft Teams: Protection against tenant-owned domain impersonation in Teams chat<\/th>\n<\/tr>\n<\/tbody>\n<\/table>\n<hr>\n<table id=\"data\">\n<tbody>\n<tr>\n<th>Classification<\/th>\n<td>planForChange<\/td>\n<\/tr>\n<tr>\n<th>Last Updated<\/th>\n<td>11\/18\/2025 16:21:05<\/td>\n<\/tr>\n<tr>\n<th>Start Time<\/th>\n<td>11\/18\/2025 16:20:25<\/td>\n<\/tr>\n<tr>\n<th>End Time<\/th>\n<td>03\/31\/2026 07:00:00<\/td>\n<\/tr>\n<tr>\n<th>Message Content<\/th>\n<td>\n<p><b>[Introduction:]<\/b><\/p>\n<p>Coming soon to <b>Microsoft Teams<\/b>: A new security feature to enhance external collaboration. If your organization allows external domains to contact users in  <i>Teams<\/i>, we will identify if an external user is impersonating a domain owned by your tenant during their initial contact through Teams chat. If we detect potential impersonation, we will show a high-risk alert to the user, notifying them to check for   suspicious name\/email and proceed with caution.<\/p>\n<p>This message is associated with Microsoft 365 Roadmap ID <a href=\"https:\/\/www.microsoft.com\/microsoft-365\/roadmap?filters=&amp;searchterms=526780\" target=\"_blank\">  526780<\/a>.<\/p>\n<p><b>[When this will happen:]<\/b><\/p>\n<p><b>General Availability: <\/b>Begins in <b>early December 2025<\/b> and expected to complete by  <b>mid-December 2025<\/b>.<\/p>\n<p><b>[How this affects your organization:]<\/b><\/p>\n<p><b>Who is affected:<\/b> Organizations that have enabled Teams external access.<\/p>\n<p><b>What will happen:<\/b><\/p>\n<ul>\n<li><b>Before rollout: <\/b>Teams only scanned for brand impersonation risks.<\/li>\n<li><b>After rollout:<\/b> Teams will <b>check for both brand<\/b> and <b>tenant-owned domain impersonation attempts<\/b>.<\/li>\n<li>When impersonation is detected, users will see the warning: <b><i>\u201cThis looks like a spam or phishing attempt\u201d  <\/i><\/b>and must preview and validate the sender before accepting the chat invitation.<\/li>\n<li>The feature will be <b>ON by default<\/b> for all tenants that <b>allow external access<\/b> in  <i>Teams<\/i>.<\/li>\n<li>There are no admin controls to manage this functionality; admins cannot disable this feature.<\/li>\n<li>No admin configuration changes are required.<\/li>\n<li><b>Platform availability: <\/b>Android, Desktop, iOS, Mac, Web<\/li>\n<\/ul>\n<p><i>Screenshot 1 &#8211; User sees this warning when the sender is detected as a potential impersonator of the tenant\u2019s own domain. In this example, the sender\u2019s domain is \u201cfabrikarn.com\u201d, which looks like the recipient tenant\u2019s own domain \u201cfabrikam.com\u201d:<\/i><\/p>\n<p><i>&nbsp;<\/i><img decoding=\"async\" style=\"width: 400px;\" alt=\"user settings\" src=\"https:\/\/cxcs.microsoft.net\/static\/public\/messagecenter\/neutral\/4105468b-f756-49df-b376-675c04ee3eb3\/bac775bd1b3f8e1c984a6726b58c6bd88bab5918.png\"><\/p>\n<\/p>\n<p><i><\/i><\/p>\n<p><i>Screenshot 2 &#8211; When user clicks on \u201cPreview their messages safely\u201d, they can see the message from the sender, and make the decision of \u201cAccept\u201d or \u201cBlock\u201d:<\/i><\/p>\n<p><i>&nbsp;<\/i><img decoding=\"async\" style=\"width: 400px;\" alt=\"user settings\" src=\"https:\/\/cxcs.microsoft.net\/static\/public\/messagecenter\/neutral\/ffb28b49-06e7-44d5-948d-8f958efd235f\/98775e9eedc72d4a2e9f7573b6cdc847c219a5a7.png\"><\/p>\n<\/p>\n<p><i><\/i><\/p>\n<p><i><\/i><\/p>\n<p><i>Screenshot 3 &#8211; If the user decides to accept, they will be prompted again to check the sender\u2019s legitimacy and confirm that they are not phishing, before the chat is officially accepted:<\/i><\/p>\n<p><i><\/i><i>&nbsp;<\/i><img decoding=\"async\" style=\"width: 400px;\" alt=\"user settings\" src=\"https:\/\/cxcs.microsoft.net\/static\/public\/messagecenter\/neutral\/de1a9fbb-69d8-4238-8381-c2bda1aa8637\/a233ec46919c97d1ffbea7e8857bf20b092a4602.png\"><i>&nbsp;<\/i><\/p>\n<p><b>[What you can do to prepare:]<\/b><\/p>\n<ul>\n<li>No action is required; this security check is automatic.<\/li>\n<li>Admins can review audit logs for impersonation attempts detected.<\/li>\n<\/ul>\n<p>Learn more:&nbsp;<a href=\"https:\/\/learn.microsoft.com\/microsoftteams\/security-compliance-overview\" target=\"_blank\">Security and compliance in Microsoft Teams | Microsoft Teams | Microsoft Learn<\/a><\/p>\n<\/p>\n<p><b>[Compliance considerations:]<\/b><\/p>\n<p>No compliance considerations identified, review as appropriate for your organization.<\/p>\n<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table><\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>MC1187679 | Microsoft Teams: Protection against tenant-owned domain impersonation in Teams chat Classification [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-13847","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/posts\/13847","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/comments?post=13847"}],"version-history":[{"count":0,"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/posts\/13847\/revisions"}],"wp:attachment":[{"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/media?parent=13847"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/categories?post=13847"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/tags?post=13847"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}