It’s alarm bells for businesses using Microsoft Teams as an indispensable collaboration tool. A recently discovered bug threatens to undermine the platform’s security, permitting malware to be delivered via external accounts.
External threats knocking on Teams’ Doors
Discovered by Jumpsec security researchers, the vulnerability could convert the popular video conferencing platform into an unsuspecting conduit for malware distribution. The exploit allows malicious software to infiltrate a company’s network from an external Teams account, leveraging default settings that permit the Teams client of a firm to accept communications from ‘external tenants’.
While such a vulnerability can lead to the manifestation of social engineering and phishing attacks, it can also enable the transmission of malware payloads into a different inbox. This can occur even in the presence of Teams’ security measures designed to block files received from external tenants.
Jumpsec researchers found an ingenious way around these security barricades. By modifying the recipient ID in a message’s POST request, both internally and externally, they tricked Teams into recognizing an external account as an internal one.
Implications and Microsoft’s response
During their analysis, the researchers succeeded in delivering a command and control payload to another organization’s inbox through a stealth operation. The alarming part is the lack of necessity to create a persuasive phishing message to lure victims. If the cybercriminal registers a domain that closely mirrors the target’s, unsuspecting employees may believe the malware-infected link is from within their own company, and thereby safe to download.
The vulnerability was reported to Microsoft. However, their response suggests they do not perceive it as an immediate threat. The company stated that it “does not meet the bar for immediate servicing,” indicating the low risk they believe this vulnerability poses. They have not yet provided a timeline for the release of a potential patch.
To counteract this threat, users can disable communication with external tenants via the Microsoft Teams Admin Center, then proceeding to ‘External Access’. If completely blocking all external communications seems too drastic, users can choose to interact only with trusted domains by adding them to the allow list.
The researchers have also posted their findings on the Microsoft Teams feedback portal. Users can up-vote this post to push Microsoft into addressing this issue at a faster pace.
A peek at Teams’ benefits despite this hiccup
Despite the recent vulnerability discovery, it’s crucial to highlight Microsoft Teams’ numerous advantages, making it an indispensable tool for many businesses. Despite the recent security concern, Microsoft Teams remains a pivotal business tool. Its seamless integration with other Microsoft apps and services facilitates efficient communication. Furthermore, its flexible communication methods and generally robust security offer a streamlined solution for business collaboration.
In light of these developments, we invite our esteemed readers to share their views on this matter. What are your thoughts on this issue? Please share your insights in the comments section below!
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