{"id":1202974,"date":"2023-11-14T15:57:58","date_gmt":"2023-11-14T20:57:58","guid":{"rendered":"https:\/\/www.prime-wow.com\/?p=1202974"},"modified":"2023-11-14T15:57:58","modified_gmt":"2023-11-14T20:57:58","slug":"intel-fixes-high-severity-cpu-bug-that-causes-very-strange-behavior","status":"publish","type":"post","link":"https:\/\/www.prime-wow.com\/?p=1202974","title":{"rendered":"Intel fixes high-severity CPU bug that causes \u201cvery strange behavior\u201d"},"content":{"rendered":"<div id=\"rss-wrap\">\n<figure class=\"intro-image intro-left\">\n  <img decoding=\"async\" src=\"https:\/\/www.prime-wow.com\/wp-content\/uploads\/2023\/11\/cpu-800x534-1.jpe\" alt=\"Intel fixes high-severity CPU bug that causes &#x201C;very strange behavior&#x201D;\" \/><\/p>\n<p class=\"caption\" style=\"font-size:0.8em\"><a href=\"https:\/\/cdn.arstechnica.net\/wp-content\/uploads\/2022\/06\/cpu.jpeg\" class=\"enlarge-link\" data-height=\"667\" data-width=\"1000\">Enlarge<\/a> <\/p>\n<\/figure>\n<div><a name=\"page-1\" \/><\/div>\n<p>On Tuesday, Intel pushed microcode updates to fix a high-severity CPU bug that has the potential to be maliciously exploited against cloud-based hosts.<\/p>\n<p>The flaw, affecting virtually all modern Intel CPUs, causes them to \u201center a glitch state where the normal rules don\u2019t apply,\u201d Tavis Ormandy, one of several security researchers inside Google who discovered the bug, <a href=\"https:\/\/lock.cmpxchg8b.com\/reptar.html\">reported<\/a>. Once triggered, the glitch state results in unexpected and potentially serious behavior, most notably system crashes that occur even when untrusted code is executed within a guest account of a virtual machine, which, under most cloud security models, is assumed to be safe from such faults. Escalation of privileges is also a possibility.<\/p>\n<h2>Very strange behavior<\/h2>\n<p>The bug, tracked under the common name Reptar and the designation CVE-2023-23583, is related to how affected CPUs manage prefixes, which change the behavior of instructions sent by running software. Intel x64 decoding generally allows redundant prefixes\u2014meaning those that don\u2019t make sense in a given context\u2014to be ignored without consequence. During testing in August, Ormandy noticed that the <code>REX<\/code> prefix was generating \u201cunexpected results\u201d when running on Intel CPUs that support a newer feature known as fast short repeat move, which was introduced in the Ice Lake architecture to fix microcoding bottlenecks.<\/p>\n<\/div>\n<p><a href=\"https:\/\/arstechnica.com\/?p=1983867#p3\">Read 8 remaining paragraphs<\/a> | <a href=\"https:\/\/arstechnica.com\/?p=1983867&amp;comments=1\">Comments<\/a><\/p>\n<p>&#013;<br \/>\n&#013;<br \/>\nSource: Ars Technica &#8211; <a href=\"https:\/\/arstechnica.com\/?p=1983867\" target=\"_blank\" rel=\"noopener\">Intel fixes high-severity CPU bug that causes \u201cvery strange behavior\u201d<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Enlarge On Tuesday, Intel pushed microcode updates to fix a high-severity CPU bug that has the potential to be maliciously exploited against cloud-based hosts. The flaw, affecting virtually all modern Intel CPUs, causes them to \u201center a glitch state where &hellip; <a href=\"https:\/\/www.prime-wow.com\/?p=1202974\">Continue reading <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":1202975,"comment_status":"open","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[27,110],"tags":[73],"class_list":["post-1202974","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-ars-technica","category-unfiltered-rss","tag-ars-technica"],"_links":{"self":[{"href":"https:\/\/www.prime-wow.com\/index.php?rest_route=\/wp\/v2\/posts\/1202974","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.prime-wow.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.prime-wow.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.prime-wow.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.prime-wow.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1202974"}],"version-history":[{"count":0,"href":"https:\/\/www.prime-wow.com\/index.php?rest_route=\/wp\/v2\/posts\/1202974\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.prime-wow.com\/index.php?rest_route=\/wp\/v2\/media\/1202975"}],"wp:attachment":[{"href":"https:\/\/www.prime-wow.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1202974"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.prime-wow.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1202974"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.prime-wow.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1202974"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}