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Update your firewall rules: Teams and Copilot are changing address

Microsoft is redirecting Microsoft 365 and Teams web users to new *.cloud.microsoft domains, requiring firewall and proxy rule updates by early October.

Starting September 2026, Microsoft is redirecting M365 web users to copilot.cloud.microsoft and Teams web users to teams.cloud.microsoft, announced via MessageCenter posts MC1465764 and MC1462915. All redirects should complete by early October 2026, with limited Teams exceptions possible until December 31, 2026. Microsoft advises reviewing client, proxy, firewall, and secure web gateway configurations, and suggests using TenantRestrictions to control personal Microsoft account access instead of blocking the new Copilot address.

CSO Online · 5d agoAdvisory1

CISA Shares 17 Techniques Used by Hackers to Compromise Active Directory

CISA and five international agencies publish joint guidance detailing 17 techniques attackers use to compromise Microsoft Active Directory environments.

CISA, NSA, and the Australian Signals Directorate's ACSC, with contributions from Canadian, UK, and New Zealand cyber centers, released technical guidance on 17 Active Directory attack techniques. It covers AD Domain Services, AD Certificate Services, and AD Federation Services, including Kerberoasting, DCSync, Golden Ticket, Golden SAML, Skeleton Key, and Shadow Credentials. The guidance recommends treating domain controllers, CAs, AD FS servers, and Entra Connect systems as Tier 0 assets with phishing-resistant MFA, Kerberos pre-authentication enforcement, and disabling NTLM/SMBv1.

Cyber Security News · 1d agoAdvisory

Microsoft Confirms KB5002914 Update Breaks Copy and Paste on Excel

Microsoft confirms KB5002914 Excel security update silently breaks copy-paste in Excel 2016-2024, forcing admins to choose between usability and security fixes.

Microsoft added a known issue to KB5002914, the September 8, 2026 Excel security update, where paste, autofill, and formula dragging fail silently with no error in Excel 2016, 2019, 2021, and 2024. The update addresses remote code execution and information disclosure flaws including CVE-2026-81399, CVE-2026-81390, and CVE-2026-81954. No hotfix date has been published as of September 15, 2026; the only widely confirmed recovery is uninstalling or rolling back KB5002914, which drops the month's Excel security fixes.

Cyber Security News · 2d agoAdvisory 3 sourcesCVE-2026-81399CVE-2026-81390CVE-2026-819542