{“lastseen”:”2025-12-22T18:05:07″,”description”:”After twenty-six years, Microsoft is finally upgrading the last remaining instance of the encryption algorithm RC4 in Windows.\\n\\n\\u003e of the most visible holdouts in supporting RC4 has been Microsoft. Eventually, Microsoft upgraded Active Directory to support the much more secure AES encryption standard. But by default, Windows servers have continued to respond to RC4-based authentication requests and return an RC4-based response. The RC4 fallback has been a favorite weakness hackers have exploited to compromise enterprise networks. Use of RC4 played a key role in last year’s breach of health giant Ascension. The breach caused life-threatening disruptions at 140 hospitals and put the medical records of 5.6 million patients into the hands of the attackers. US Senator Ron Wyden (D-Ore.) in September called on the Federal Trade Commission to investigate Microsoft for \\”gross cybersecurity negligence,\\” citing the continued default support for RC4.\\n\\u003e \\n\\u003e Last week, Microsoft said it was finally deprecating RC4 and cited its susceptibility to Kerberoasting, the form of attack, known since 2014, that was the root cause of the initial intrusion into Ascension’s network.\\n\\nFun fact: RC4 was a trade secret until I published the algorithm in the second edition of _Applied Cryptography_ in 1995.”,”published”:”2025-12-22T17:05:09″,”modified”:”2025-12-22T17:05:09″,”type”:”schneier”,”title”:”Microsoft Is Finally Killing RC4″,”source”:””,”references”:””,”id”:”SCHNEIER:6754DE97707CD20A33ED674076B3795B”,”bulletinFamily”:”blog”,”cwe”:null,”cvelist”:[],”sourceData”:””,”sourceHref”:””,”cvss”:{“score”:0,”severity”:”NONE”,”vector”:”NONE”,”version”:”NONE”},”cvss2″:{},”cvss3″:{“version”:””,”vectorString”:””,”baseScore”:0,”baseSeverity”:””,”attackVector”:””,”attackComplexity”:””,”privilegesRequired”:””,”userInteraction”:””,”scope”:””,”confidentialityImpact”:””,”integrityImpact”:””,”availabilityImpact”:””,”cvssV3″:{“version”:””,”vectorString”:””,”baseScore”:0,”baseSeverity”:””,”attackVector”:””,”attackComplexity”:””,”privilegesRequired”:””,”userInteraction”:””,”scope”:””,”confidentialityImpact”:””,”integrityImpact”:””,”availabilityImpact”:””}},”href”:”https:\/\/www.schneier.com\/blog\/archives\/2025\/12\/microsoft-is-finally-killing-rc4.html”,”category_name”:”News”,”post_link”:””,”product”:””,”version”:””,”vendor”:””,”ai_description”:””,”ai_severity”:””,”ai_vendor”:””,”ai_product”:””,”ai_version”:””,”ai_score”:0}<\/p>\n","protected":false},"excerpt":{"rendered":"
{“lastseen”:”2025-12-22T18:05:07″,”description”:”After twenty-six years, Microsoft is finally upgrading the last remaining instance of the encryption algorithm RC4 in Windows.\\n\\n\\u003e of the most visible holdouts in supporting…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4],"tags":[6,8,12,13,33,114,7,11,5],"class_list":["post-32457","post","type-post","status-publish","format-standard","hentry","category-category_news","tag-cve","tag-cvss","tag-exploit","tag-news","tag-none","tag-schneier","tag-security","tag-tapic","tag-vulnerability"],"yoast_head":"\n