Security News > 2023 > July > New tool exploits Microsoft Teams bug to send malware to users
A member of U.S. Navy's red team has published a tool called TeamsPhisher that leverages an unresolved security issue in Microsoft Teams to bypass restrictions for incoming files from users outside of a targeted organization, the so-called external tenants.
The tool exploits a problem highlighted last month by Max Corbridge and Tom Ellson of UK-based security services company Jumpsec, who explained how an attacker could easily go around Microsoft Teams' file-sending restraints to deliver malware from an external account.
"Give TeamsPhisher an attachment, a message, and a list of target Teams users. It will upload the attachment to the sender's Sharepoint, and then iterate through the list of targets," reads the description from Alex Reid, the developer of the red team utility.
TeamsPhisher requires users to have a Microsoft Business account with a valid Teams and Sharepoint license, which is common for many major companies.
Microsoft Teams bug allows malware delivery from external accounts.
Microsoft 365 phishing attacks use encrypted RPMSG messages.
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