{"id":18299,"date":"2026-09-03T03:03:46","date_gmt":"2026-09-02T18:03:46","guid":{"rendered":"https:\/\/m365jp.net\/?p=18299"},"modified":"2026-09-03T03:05:20","modified_gmt":"2026-09-02T18:05:20","slug":"mc1422060-updated-microsoft-defender-for-office-365-prompt-injection-protection-for-email","status":"publish","type":"post","link":"https:\/\/m365jp.net\/index.php\/2026-09-03-mc1422060-updated-microsoft-defender-for-office-365-prompt-injection-protection-for-email","title":{"rendered":"MC1422060 | (Updated) Microsoft Defender for Office 365: Prompt injection protection for email"},"content":{"rendered":"<div class=\"postie-post\">\n<div>\n<hr>\n<table id=\"section\">\n<tbody>\n<tr>\n<th width=\"95%\">MC1422060 | (Updated) Microsoft Defender for Office 365: Prompt injection protection for email<\/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>09\/02\/2026 17:03:17<\/td>\n<\/tr>\n<tr>\n<th>Start Time<\/th>\n<td>07\/09\/2026 21:50:12<\/td>\n<\/tr>\n<tr>\n<th>End Time<\/th>\n<td>11\/16\/2026 07:00:00<\/td>\n<\/tr>\n<tr>\n<th>Message Content<\/th>\n<td>\n<p>Updated September 2, 2026: We have updated the timeline. Thank you for your patience.&nbsp;<\/p>\n<p><b>[What and Why]<\/b><\/p>\n<p>We are introducing prompt injection protection for email in <i>Microsoft Defender for Office 365<\/i>. This capability detects and blocks malicious prompt injection content embedded in email messages that attempt to manipulate AI assistants and agents. It   helps protect enterprise data by identifying attacks designed to exfiltrate information, discover tools, or expose system prompts. High confidence threats are automatically quarantined before they can be processed by AI powered workflows. This enhancement   strengthens enterprise ready AI security and aligns with evolving threat patterns.<\/p>\n<p><b>[Rollout Schedule]<\/b><\/p>\n<ul>\n<li><b>Public Preview:<\/b> Beginning <b>early July 2026<\/b> and expected to complete by  <b>early September 2026<\/b><\/li>\n<li><b>General Availability (Worldwide):<\/b> Beginning <b>early October 2026<\/b> (previously&nbsp;early September)&nbsp;and expected to complete by  <b>early October 2026<\/b> (previously&nbsp;early September)<\/li>\n<\/ul>\n<p><b>[Impact on Your Organization]<\/b><\/p>\n<p><i>Who is affected<\/i><\/p>\n<ul>\n<li>Organizations with Microsoft Defender for Office 365 Plan 2 or Microsoft 365 E5<\/li>\n<\/ul>\n<p><i>Platforms and services<\/i><\/p>\n<ul>\n<li>&nbsp;Exchange Online, Microsoft Defender for Office 365, Microsoft Defender XDR services<\/li>\n<\/ul>\n<p><i>What will happen<\/i><\/p>\n<ul>\n<li>Emails identified as prompt injection will be classified as <b>High Confidence Phish<\/b>.<\/li>\n<li>A new Detection Technology value called <b>Prompt Injection Protection<\/b> will be applied.<\/li>\n<li>High confidence threats will be automatically quarantined.<\/li>\n<li>The feature is <b>enabled by default<\/b> for eligible tenants.<\/li>\n<li>Existing policies and workflows remain unchanged.<\/li>\n<li>These detections will appear within existing threat investigation and reporting experiences in  <i>Microsoft Defender<\/i>.<\/li>\n<\/ul>\n<p><b>[Action Required \/ Recommendations]<\/b><\/p>\n<p>No action is required.<\/p>\n<p>Recommended actions:<\/p>\n<ul>\n<li>Review your submission and quarantine workflows.<\/li>\n<li>Use the Microsoft Defender submission process if false positives occur.<\/li>\n<li>Use Tenant Allow Block List if needed to manage exceptions.<\/li>\n<li>Inform your security and helpdesk teams about the new detection category.<\/li>\n<\/ul>\n<p><b>Learn more:<\/b>&nbsp;<a href=\"https:\/\/learn.microsoft.com\/defender-office-365\/step-by-step-guides\/prompt-injection-protection-defender-for-office-365\" target=\"_blank\">Prompt injection protection in Microsoft Defender for Office 365 | Microsoft Defender for   Office 365 | Microsoft Defender | Microsoft Learn<\/a><\/p>\n<p><b>[Compliance considerations]<\/b><\/p>\n<p>No compliance considerations identified, review as appropriate for your organization.<\/p>\n<\/td>\n<\/tr>\n<tr>\n<th>Machine Translation<\/th>\n<td>\n<p>2026\u5e749\u67082\u65e5\u66f4\u65b0:\u30bf\u30a4\u30e0\u30e9\u30a4\u30f3\u3092\u66f4\u65b0\u3057\u307e\u3057\u305f\u3002\u3054\u8f9b\u62b1\u3044\u305f\u3060\u304d\u3042\u308a\u304c\u3068\u3046\u3054\u3056\u3044\u307e\u3059\u3002&nbsp;<\/p>\n<p><b>\u3010\u4f55\u3068\u306a\u305c\u3011<\/b><\/p>\n<p>Microsoft <i>Defender for Office 365<\/i>\u3067\u30e1\u30fc\u30eb\u7528\u306e\u30d7\u30ed\u30f3\u30d7\u30c8\u30a4\u30f3\u30b8\u30a7\u30af\u30b7\u30e7\u30f3\u4fdd\u8b77\u3092\u5c0e\u5165\u3057\u307e\u3059\u3002\u3053\u306e\u6a5f\u80fd\u306f\u3001AI\u30a2\u30b7\u30b9\u30bf\u30f3\u30c8\u3084\u30a8\u30fc\u30b8\u30a7\u30f3\u30c8\u3092\u64cd\u4f5c\u3057\u3088\u3046\u3068\u3059\u308b\u30e1\u30fc\u30eb\u30e1\u30c3\u30bb\u30fc\u30b8\u306b\u57cb\u3081\u8fbc\u307e\u308c\u305f\u60aa\u610f\u306e\u3042\u308b\u30d7\u30ed\u30f3\u30d7\u30c8\u30a4\u30f3\u30b8\u30a7\u30af\u30b7\u30e7\u30f3\u30b3\u30f3\u30c6\u30f3\u30c4\u3092\u691c\u51fa\u30fb\u30d6\u30ed\u30c3\u30af\u3057\u307e\u3059\u3002\u60c5\u5831\u306e\u6d41\u51fa\u3001\u30c4\u30fc\u30eb\u306e\u767a\u898b\u3001\u30b7\u30b9\u30c6\u30e0\u30d7\u30ed\u30f3\u30d7\u30c8\u306e\u9732\u51fa\u3092\u76ee\u7684\u3068\u3057\u305f\u653b\u6483\u3092\u7279\u5b9a\u3057\u3001\u4f01\u696d\u30c7\u30fc\u30bf\u3092\u4fdd\u8b77\u3057\u307e\u3059\u3002\u9ad8\u3044\u4fe1\u983c\u5ea6\u306e\u8105\u5a01\u306f\u3001AI\u642d\u8f09\u306e\u30ef\u30fc\u30af\u30d5\u30ed\u30fc\u3067\u51e6\u7406\u3055\u308c\u308b\u524d\u306b\u81ea\u52d5\u7684\u306b\u9694\u96e2\u3055\u308c\u307e\u3059\u3002\u3053\u306e\u5f37\u5316\u306f\u4f01\u696d\u5411\u3051\u306eAI\u30bb\u30ad\u30e5\u30ea\u30c6\u30a3\u3092\u5f37\u5316\u3057\u3001\u9032\u5316\u3059\u308b\u8105\u5a01\u30d1\u30bf\u30fc\u30f3\u306b\u6cbf\u3044\u307e\u3059\u3002<\/p>\n<p><b>[\u5c55\u958b\u30b9\u30b1\u30b8\u30e5\u30fc\u30eb]<\/b><\/p>\n<ul>\n<li><b>\u30d1\u30d6\u30ea\u30c3\u30af\u30d7\u30ec\u30d3\u30e5\u30fc:<\/b><b>2026\u5e747\u6708\u521d\u65ec<\/b>\u304b\u3089<b>2026\u5e749\u6708\u521d<\/b>\u65ec\u307e\u3067\u306b\u5b8c\u4e86\u4e88\u5b9a\u3067\u3059<\/li>\n<li><b>\u4e00\u822c\u516c\u958b(\u4e16\u754c\u5c55\u958b):<\/b><b>2026\u5e7410\u6708\u521d\u65ec<\/b>(\u4ee5\u524d&nbsp;\u306f&nbsp;9\u6708\u521d\u65ec)\u304b\u3089<b>2026\u5e7410\u6708\u521d\u65ec<\/b>(\u4ee5\u524d&nbsp;\u306f9\u6708\u521d\u65ec)\u307e\u3067\u306b\u5b8c\u4e86\u4e88\u5b9a\u3067\u3059\u3002<\/li>\n<\/ul>\n<p><b>[\u7d44\u7e54\u3078\u306e\u5f71\u97ff]<\/b><\/p>\n<p><i>\u5f71\u97ff\u3092\u53d7\u3051\u308b\u4eba\u7269<\/i><\/p>\n<ul>\n<li>Microsoft Defender for Office 365 Plan 2 \u307e\u305f\u306f Microsoft 365 E5 \u3092\u4f7f\u7528\u3057\u3066\u3044\u308b\u7d44\u7e54<\/li>\n<\/ul>\n<p><i>\u30db\u30fc\u30e0\u3068\u30b5\u30fc\u30d3\u30b9<\/i><\/p>\n<ul>\n<li>&nbsp;Exchange Online\u3001Microsoft Defender for Office 365\u3001Microsoft Defender XDR services<\/li>\n<\/ul>\n<p><i>\u4f55\u304c\u8d77\u3053\u308b\u306e\u304b<\/i><\/p>\n<ul>\n<li>\u30d7\u30ed\u30f3\u30d7\u30c8\u30a4\u30f3\u30b8\u30a7\u30af\u30b7\u30e7\u30f3\u3068\u8a8d\u5b9a\u3055\u308c\u305f\u30e1\u30fc\u30eb\u306f\u3001 <b>\u9ad8\u4fe1\u983c\u30d5\u30a3\u30c3\u30b7\u30e5<\/b>\u306b\u5206\u985e\u3055\u308c\u307e\u3059\u3002<\/li>\n<li>\u65b0\u3057\u3044\u691c\u51fa\u6280\u8853\u306e\u5024\u3067\u3042\u308b <b>\u30d7\u30ed\u30f3\u30d7\u30c8\u30a4\u30f3\u30b8\u30a7\u30af\u30b7\u30e7\u30f3<\/b> \u4fdd\u8b77\u304c\u9069\u7528\u3055\u308c\u307e\u3059\u3002<\/li>\n<li>\u9ad8\u3044\u4fe1\u983c\u5ea6\u306e\u8105\u5a01\u306f\u81ea\u52d5\u7684\u306b\u9694\u96e2\u3055\u308c\u307e\u3059\u3002<\/li>\n<li>\u3053\u306e\u6a5f\u80fd\u306f\u3001\u5bfe\u8c61\u3068\u306a\u308b\u30c6\u30ca\u30f3\u30c8\u306b\u5bfe\u3057\u3066 <b>\u30c7\u30d5\u30a9\u30eb\u30c8\u3067\u6709\u52b9\u5316<\/b> \u3055\u308c\u3066\u3044\u307e\u3059\u3002<\/li>\n<li>\u65e2\u5b58\u306e\u30dd\u30ea\u30b7\u30fc\u3084\u30ef\u30fc\u30af\u30d5\u30ed\u30fc\u306f\u5909\u66f4\u3055\u308c\u3066\u3044\u307e\u305b\u3093\u3002<\/li>\n<li>\u3053\u308c\u3089\u306e\u691c\u51fa\u306f <i>\u3001Microsoft Defender<\/i>\u306e\u65e2\u5b58\u306e\u8105\u5a01\u8abf\u67fb\u304a\u3088\u3073\u5831\u544a\u4f53\u9a13\u5185\u306b\u53cd\u6620\u3055\u308c\u307e\u3059\u3002<\/li>\n<\/ul>\n<p><b>[\u884c\u52d5\u304c\u5fc5\u8981\/\u52e7\u544a]<\/b><\/p>\n<p>\u4f55\u306e\u5bfe\u5fdc\u3082\u5fc5\u8981\u3042\u308a\u307e\u305b\u3093\u3002<\/p>\n<p>\u63a8\u5968\u3055\u308c\u308b\u884c\u52d5:<\/p>\n<ul>\n<li>\u63d0\u51fa\u66f8\u985e\u3092\u898b\u76f4\u3057\u3001\u9694\u96e2\u4f5c\u696d\u3092\u884c\u3063\u3066\u304f\u3060\u3055\u3044\u3002<\/li>\n<li>\u8aa4\u691c\u77e5\u304c\u767a\u751f\u3057\u305f\u5834\u5408\u306fMicrosoft Defender\u306e\u63d0\u51fa\u30d7\u30ed\u30bb\u30b9\u3092\u3054\u5229\u7528\u304f\u3060\u3055\u3044\u3002<\/li>\n<li>\u4f8b\u5916\u7ba1\u7406\u306b\u5fc5\u8981\u306a\u5834\u5408\u306f\u30c6\u30ca\u30f3\u30c8\u8a31\u53ef\u30d6\u30ed\u30c3\u30af\u30ea\u30b9\u30c8\u3092\u4f7f\u3044\u307e\u3057\u3087\u3046\u3002<\/li>\n<li>\u65b0\u3057\u3044\u691c\u51fa\u30ab\u30c6\u30b4\u30ea\u306b\u3064\u3044\u3066\u3001\u30bb\u30ad\u30e5\u30ea\u30c6\u30a3\u304a\u3088\u3073\u30d8\u30eb\u30d7\u30c7\u30b9\u30af\u30c1\u30fc\u30e0\u306b\u77e5\u3089\u305b\u3066\u304f\u3060\u3055\u3044\u3002<\/li>\n<\/ul>\n<p><b>\u8a73\u3057\u304f\u306f\u3053\u3061\u3089:<\/b>&nbsp;<a href=\"https:\/\/learn.microsoft.com\/defender-office-365\/step-by-step-guides\/prompt-injection-protection-defender-for-office-365\" target=\"_blank\">Microsoft Defender for Office 365\u306b\u304a\u3051\u308b\u30d7\u30ed\u30f3\u30d7\u30c8\u30a4\u30f3\u30b8\u30a7\u30af\u30b7\u30e7\u30f3\u4fdd\u8b77 |Microsoft Defender for Office 365 |Microsoft   Defender |Microsoft Learn<\/a><\/p>\n<p><b>[\u30b3\u30f3\u30d7\u30e9\u30a4\u30a2\u30f3\u30b9\u306e\u8003\u616e\u4e8b\u9805]<\/b><\/p>\n<p>\u30b3\u30f3\u30d7\u30e9\u30a4\u30a2\u30f3\u30b9\u4e0a\u306e\u61f8\u5ff5\u4e8b\u9805\u306f\u7279\u5b9a\u3055\u308c\u305a\u3001\u7d44\u7e54\u306b\u5fdc\u3058\u3066\u30ec\u30d3\u30e5\u30fc\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table><\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>MC1422060 | (Updated) Microsoft Defender for Office 365: Prompt injection protection for email 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-18299","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/posts\/18299","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=18299"}],"version-history":[{"count":0,"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/posts\/18299\/revisions"}],"wp:attachment":[{"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/media?parent=18299"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/categories?post=18299"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/tags?post=18299"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}