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vpnMentor was established in 2014 as an independent site reviewing VPN services and covering privacy-related stories. Today, our team of hundreds of cybersecurity researchers, writers, and editors continues to help readers fight for their online freedom in partnership with Kape Technologies PLC, which also owns the following products: ExpressVPN, CyberGhost, and Private Internet Access which may be ranked and reviewed on this website. The reviews published on vpnMentor are believed to be accurate as of the date of each article, and written according to our strict reviewing standards that prioritize the independent, professional and honest examination of the reviewer, taking into account the technical capabilities and qualities of the product together with its commercial value for users. The rankings and reviews we publish may also take into consideration the common ownership mentioned above, and affiliate commissions we earn for purchases through links on our website. We do not review all VPN providers and information is believed to be accurate as of the date of each article.

Microsoft Teams Vulnerability Allows Hackers to Plant Malware

Microsoft Teams Vulnerability Allows Hackers to Plant Malware
Husain Parvez Published on 7th July 2023 Cybersecurity Researcher

A tool named TeamsPhisher, developed and released by a U.S. Navy's Red team member, exploits an unaddressed security vulnerability within Microsoft Teams. This tool allows users to bypass restrictions on incoming files from external tenants, which are users outside the organization. By circumventing these restrictions, the tool opens up the possibility for potentially unauthorized files to enter the targeted organization's systems.

In a recent discovery, researchers found a new attack pathway in popular communication platforms like Teams, Slack, and Zoom. As traditional infection routes, such as email inboxes and websites, receive more scrutiny, hackers are exploring alternative methods to exploit vulnerabilities in these platforms.

According to the cybersecurity team at Jumpsec Labs, this vulnerability affects organizations utilizing the default configuration of Microsoft Teams. By bypassing client-side security controls, external tenants gain the ability to send malicious files to employees within the organization.

Max Corbridge, a researcher from Jumpsec's Red Team, highlighted this issue in a research note posted last week. He elaborated on how an attacker can effectively circumvent the file-sending restrictions in Microsoft Teams to distribute malware from an external account.

Developed in Python, TeamsPhisher takes advantage of the application's dependency on client-side protections, which can be manipulated by modifying the ID in a POST request for a message. By utilizing TeamsPhisher, users can upload attachments to their SharePoint and send messages to targeted Teams users, making it appear as if the message originated from an internal user, even if the sender is actually from an external tenant.

Microsoft has acknowledged the presence of TeamsPhisher and recognizes that the tool's effectiveness relies on social engineering techniques. The company urges users to adopt responsible online practices and exercise caution when engaging with different elements online, such as clicking on website links, opening unknown files, or accepting file transfers.

About the Author

Husain Parvez is a Cybersecurity Researcher and News Writer at vpnMentor, focusing on VPN reviews, detailed how-to guides, and hands-on tutorials. Husain is also a part of the vpnMentor Cybersecurity News bulletin and loves covering the latest events in cyberspace and data privacy.