"Remain vigilant and be cautious of unsolicited contact," Australian National Cyber Security Coordinator Michelle McGuiness warned in an update on November 13, as organisations worldwide coped with a Microsoft 365 outage that affected services that interact with Exchange Online, most notably Outlook.
Microsoft's recovery status
Microsoft told customers that recovery efforts were ongoing across the impacted infrastructure. The company said it was "seeing early signs of stabilization, but service capacity has not yet returned to normal levels and health remains variable as traffic is carefully reintroduced." That phased reintroduction of traffic and partial service capacity creates a prolonged period of uneven visibility for organisations relying on cloud-hosted mail and related controls.
Why attackers are likely to exploit the outage
Although the outage is "not believed to be cyber-related," security professionals quoted in reporting warned that the operational disruption itself creates an attractive window for malicious actors. Marie Wilcox, vice president of market strategy at digital forensics firm Binalyze, said: "Just because this outage wasn’t caused by a cyber-attack, doesn’t mean attackers won’t seize the opportunity." Jake Moore, Global Cybersecurity Advisor at ESET, described the disruption as "the perfect excuse for cybercriminals to hit organizations with targeted calls posing as IT support," noting that "affected employees are literally waiting by the phone (or scrolling on social media!), and it only takes one employee to grant access to their machine for threat actors to gain access, escalate their privileges and wreak havoc on systems."
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See what we buildBinalyze: treat the outage window as an incident
Wilcox emphasised that the outage window should be handled as a distinct security incident. She warned that many security teams themselves "will have been locked out of tools they depend on to prevent trouble, for example Microsoft Defender XDR or important alerts pushed via Outlook." When services return, she said, employees clearing backlogs will be especially susceptible to phishing or fake security updates: "When email services return and workers are beginning to clear the day’s backlog, this is when they will be most susceptible to trusting any messages that looks like they came from Microsoft – especially fake security updates."
Her concrete advice was procedural: go back over sign-ins, mailbox rules, account changes and endpoint activity for the hours when visibility dropped, and collect evidence directly from devices rather than relying on the platform that was down. She also noted that "a suspicious sign-in or a new inbox forwarding rule is easy to miss when everyone is focused on getting email back."
Check Point Q3 2026: Microsoft dominates brand phishing
The reason attackers favour Microsoft branding is visible in recent phishing metrics. Check Point reported that in Q3 2026 Microsoft accounted for 33% of all brand phishing attempts, up from 23% in Q2 2026 and "roughly four times the share of any other brand." That statistical dominance underscores why defenders should expect phishing and impersonation scams tied to this outage.
What this means for security teams, banks and shops, and end users
- Security teams: Expect reduced visibility during the outage and treat the event as an incident. Audit sign-ins, mailbox rules and account changes covering the outage window and collect forensic evidence from endpoints rather than assuming cloud logs are complete.
- Banks and shops (affected businesses): As Aiden Sinnott, principal threat researcher at the Sophos Counter Threat Unit, said, these types of businesses "should be particularly vigilant"—watch for requests for urgent action, avoid sharing personal information, and do not click links received via message or email.
- End users: Follow Michelle McGuiness's advice to remain vigilant and be cautious of unsolicited contact. Be especially wary of messages purporting to be Microsoft security updates or urgent IT support requests; a single employee granting access can enable privilege escalation, according to Jake Moore.
The outage may not be an attack, but the operational consequences mimic the conditions attackers want: frustrated users, delayed alerts, and a rush to restore services. With Microsoft signaling only early stabilization and uneven service health, organisations should assume malicious actors will try to weaponise the confusion and respond by treating the outage period itself as a forensics and response priority.
