All news with #microsoft teams tag

Microsoft Teams adds false-positive threat report option

🔔 Microsoft is adding a user-driven false-positive reporting capability to Microsoft Teams, allowing users to flag chat or channel messages they believe were incorrectly marked as security threats. The feature began a targeted rollout in September and is scheduled to reach general availability worldwide by the end of November 2025. It will be available to organizations using Microsoft Defender for Office 365 Plan 2 or Microsoft Defender XDR, and accessible on desktop, mobile, and web. Administrators can enable or disable the feature from the Teams admin center or the Microsoft Defender portal.

Microsoft deploys Teams screen-capture prevention rollout

🔒 Microsoft is rolling out a new Teams Premium setting that blocks screenshots and recordings in meetings on Windows desktop and Android devices. The feature, called 'Prevent screen capture', was announced for July 2025 but the rollout was delayed and is being introduced in late November 2025. The control is off by default and must be enabled per meeting by organizers or co-organizers; unsupported clients will join audio-only.

Microsoft Teams Bugs Enable Message and Caller Spoofing

🔒 Check Point researchers disclosed four vulnerabilities in Microsoft Teams that let attackers alter message content, spoof senders, and manipulate notifications to impersonate colleagues. The issues were reported in March 2024 and remediated across multiple updates beginning with an August 2024 fix for CVE-2024-38197, followed by patches in September 2024 and October 2025. Exploitable by external guests and internal actors alike, the flaws could trick users into clicking malicious links, sharing sensitive data, or accepting fraudulent calls by making messages and caller notifications appear to originate from trusted executives or coworkers.

Microsoft Disrupts Rhysida Ransomware Targeting Teams

🔒 Microsoft disrupted a campaign by the financially motivated group Vanilla Tempest (also tracked as VICE SPIDER/Vice Society) after revoking over 200 code signing certificates used to sign malicious Microsoft Teams installers. The attackers used malvertising and SEO-poisoned domains mimicking Teams to distribute fake MSTeamsSetup.exe files that deployed the Oyster backdoor. The intervention curtailed a wave of Rhysida ransomware launches.

Microsoft 365 Outage Disrupts Teams, Exchange, and MFA

⚠️ Microsoft is addressing an ongoing outage that is preventing users from accessing Microsoft 365 services, including Teams, Exchange Online, and the Microsoft 365 admin center. The incident is being tracked on the Service Health Dashboard and Microsoft is publishing updates on its Service Health Status page. The outage is also affecting Microsoft Entra single sign-on and Multi-Factor Authentication, with some users unable to receive MFA prompts or authenticate.

Disrupting Threats Targeting Microsoft Teams Environments

🛡️ Microsoft Threat Intelligence details how adversaries exploit Microsoft Teams collaboration capabilities—chat, calls, meetings, and screen sharing—at multiple stages of the attack chain. The post chronicles 2024–2025 campaigns and toolsets (phishing, malvertising, deepfakes, device code phishing, and red‑team tool reuse) that enable initial access, persistence, and exfiltration. It emphasizes layered defenses across identity, endpoints, apps, data, and network controls, and provides detection guidance, hunting queries, and product-specific recommendations to help defenders disrupt these operations.

Fake Microsoft Teams Installer Delivers Oyster Backdoor

⚠️ Blackpoint SOC observed a malvertising and SEO-poisoning campaign that directs searches for Teams downloads to a fake site at teams-install[.]top offering a malicious MSTeamsSetup.exe. The signed installer uses certificates from "4th State Oy" and "NRM NETWORK RISK MANAGEMENT INC" to appear legitimate, then drops CaptureService.dll into %APPDATA%\Roaming and creates a scheduled task CaptureService to run every 11 minutes. The payload installs the Oyster backdoor. Administrators should download software only from verified vendor domains and avoid clicking search ads.

Microsoft adds malicious link warnings to Teams chats

🔔 Microsoft Teams will display warnings on private messages that contain URLs flagged as spam, phishing, or malware for customers using Microsoft Defender for Office 365 and enterprise Teams. The feature enters public preview for desktop, Android, web, and iOS in September 2025 and is slated for general availability in November 2025. Admins can enable the preview via the Teams Admin Center messaging settings; warnings will be enabled by default at GA and can be managed through the Teams Admin Center or PowerShell.

Microsoft anti-spam bug blocks URLs in Exchange, Teams

🔒 Microsoft is addressing a known anti-spam issue that has caused its service to incorrectly block URLs in Exchange Online and Microsoft Teams, and to quarantine some messages. The engine erroneously flags URLs embedded inside other URLs as malicious, creating alerts and preventing users from opening links that were already confirmed safe. Engineers deployed a fix to stop further quarantines and are unblocking over 6,000 affected URLs, but additional impacted links and residual message recovery remain under active remediation while a root cause analysis continues.

Fake IT Support Phishing Targets Microsoft Teams Users

🔒 Researchers at Permiso have uncovered phishing campaigns that abuse Microsoft Teams by impersonating IT support to trick employees into installing remote access tools like QuickAssist and AnyDesk. Attackers gain full control of compromised endpoints, deploy credential-stealing malware and establish persistence. Campaigns are linked to the financially motivated actor EncryptHub and use simple impersonation tactics that bypass email defences. Security teams should monitor unusual external Teams activity and verify unexpected support requests.