Microsoft has patched a vulnerability in Teams that could have been exploited by hackers to hijack accounts by sending malicious links or GIFs
Eduard Kovacs / SecurityWeek :
Context & Ripple Effects
This is the second time in roughly a year and a half that Microsoft has had to close an account-hijacking hole in its own sign-in or collaboration stack: in late 2018 a researcher showed a misconfigured domain let anyone hijack an Office account, and now Teams turns out to have been exploitable through nothing more exotic than a malicious link or GIF sent in chat.
The pattern matters because Teams was becoming the default corporate communications hub just as remote work surged in early 2020 — a single click inside a trusted chat window is a far more convincing lure than an email attachment, and the bug sat one layer below where most enterprise security budgets were pointed.
First-order effects
- Organizations running Teams had to apply Microsoft's patch to close a channel where any coworker-seeming message containing a crafted link or GIF could hand an attacker control of a victim's account.
- Security teams gained a new audit item: chat-delivered lures targeting the collaboration client itself, not just email gateways.
Second-order effects
- Independent researchers kept pressure on Teams' security posture — three years later Vectra disclosed that the platform stores authentication tokens in unencrypted plaintext, with Microsoft declining a fix on the grounds that exploitation requires network access.
- Rival collaboration vendors face the same exposure class, since rich-content previews and link unfurling are table-stakes features that turn every shared object into potential attack surface.
Third-order effects
- If the pattern holds, collaboration suites become a primary breach vector alongside email, pushing regulators and enterprise buyers to demand the same hardening and disclosure rigor from chat platforms that they expect from operating systems — a bar Microsoft's own catalog, from the 2017 malware protection engine RCE to the 2026 Notepad malicious-Markdown-link flaw, shows it keeps tripping over across its product line.
The trend: Microsoft's collaboration and productivity clients are becoming a recurring account-takeover attack surface, with social-engineering payloads like links and GIFs replacing traditional malware attachments.