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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

August updates trigger 0xc0000409 errors on Windows Server 2016

Microsoft says the August 2026 security update causes recurring CompatTelRunner.exe 0xc0000409 crashes on Windows Server 2016 with Compatibility Appraiser enabled; no functional impact.

Microsoft confirmed a known issue in which the August 2026 Windows security update generates recurring Application Error events (Event ID 1000, exception code 0xc0000409) in CompatTelRunner.exe on Windows Server 2016. The issue affects physical and virtual machines, including VMware and Azure environments, and per Microsoft does not affect device functionality. A permanent fix is planned for a future update, and the event log entries can be dismissed temporarily.

BleepingComputer · 8d agoAdvisory

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

Windows memory integrity switches on automatically for eligible devices in October 2026

Microsoft's Windows quality updates will automatically enable memory integrity and Virtualization-based Security on eligible devices starting October 2026.

Beginning in October 2026, Windows quality updates will automatically enable memory integrity on eligible devices and turn on Virtualization-based Security where it is not already running. Memory integrity restricts kernel-mode execution to trusted, signed code and drivers, blocking kernel compromise and rootkits. Microsoft said existing administrator decisions remain in effect, and readiness checks weigh hardware capability, compatibility, and performance. Memory integrity also underpins hotpatch updates that install without a reboot, so unprotected devices are excluded from that servicing model.

Help Net Security · 14d agoAdvisory1

Water sector passes, government sector fails attempts to spot and halt simulated CISA attack

CISA red teamers compromised both a government and a water organization; water defenders detected and contained the simulated attack, government defenders did not.

CISA's red team gained initial access, elevated domain privileges, and lateral movement into sensitive business systems and cloud resources at an unnamed government organization, whose SOC ignored low- and medium-severity EDR alerts buried under thousands of false positives. A water organization's SOC quarantined phishing-compromised workstations within 2, 10, and 20 minutes, and later detected and isolated intrusions reaching the OT DMZ bastion host. Both organizations underestimated cloud risk, lacked Microsoft Conditional Access for workload identities, and had no process to revoke compromised access and refresh tokens. This is one of CISA's rare public red-team reports since 2023.

CyberScoop · 22d agoAdvisory1

CISA and NIST Issue Guidance to Protect Cloud Identity Tokens

CISA and NIST published Interagency Report 8587 with voluntary guidance to harden cloud identity tokens against theft, forgery, and lateral movement.

CISA and NIST released NIST Interagency Report 8587 on September 15 with final voluntary guidance for federal agencies, cloud providers, and their customers on protecting SSO, federation, and API tokens. Requirements include one-hour maximum token lifetimes, 90-day signing key rotation for high-impact systems, hardware-backed key storage, explicit audience fields, and keeping tokens out of logs. The guidance was motivated by the 2020 ADFS compromise where forged SAML assertions bypassed MFA, and an incident where a leaked consumer signing key enabled token forgery and theft of 60,000+ emails from one agency. Nearly 250 public comments shaped the text, with input from Google, Microsoft, Okta, AWS, Oracle, IBM, HashiCorp, Wiz, and the OpenID Foundation via the Joint Cyber Defense Collaborative.

Infosecurity Magazine · 18h agoAdvisory

CISA Warns Hackers Exploit 17 Active Directory Techniques to Gain Control of Enterprise Networks

CISA and Five Eyes agencies issued joint guidance detailing 17 Active Directory attack techniques like Kerberoasting and DCSync, with hardening and detection advice.

CISA, the NSA, and cyber agencies from Australia, Canada, the UK, and New Zealand released joint guidance on September 15 covering 17 techniques attackers use to compromise Active Directory, including AD CS, Certificate Services, and Federation Services attacks. Named techniques include Kerberoasting, AS-REP roasting, password spraying, DCSync, NTDS.dit dumping, Golden and Silver Tickets, Golden SAML, and Skeleton Key. Recommendations include minimizing SPN accounts, enforcing AES encryption, disabling NTLM, account lockout thresholds of five attempts, phishing-resistant MFA, and Tier 0 prioritization. The guide also lists Windows event IDs 4769, 4768, 4625, 4771, and 2889 for detecting Kerberoasting and password spraying on domain controllers.

GBHackers · 1d agoAdvisory