Microsoft Teams bug allowing phishing unpatched since March

Microsoft said it won’t fix or is delaying patches for several security flaws impacting Microsoft Team’s link preview feature reported since March 2021.

Bräunlein reported the four flaws to the Microsoft Security Response Center, which investigates vulnerability reports concerning Microsoft products and services.

“The vulnerabilities allow accessing internal Microsoft services, spoofing the link preview, and, for Android users, leaking their IP address and DoS’ing their Teams app/channels,” the researcher said.

The URL preview spoofing bug that threat actors could use for phishing attacks or camouflage malicious links was tagged as not posing any danger to Teams users.

The company’s decision not to address the spoofing bug which could be abused in phishing campaigns is partially explained by Teams also using Defender for Office 365 Safe Links protection to safeguard users from URL-based phishing attacks since July.

While Safe Links protection is available to all Teams users and works for links shared across conversations, group chats, and Teams channels, it still needs to be enabled by setting up a Safe Links policy in the Microsoft 365 Defender portal.

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