Microsoft has patched a vulnerability in Teams that could have been exploited by hackers to hijack accounts by sending malicious links or GIFs
Microsoft has addressed a vulnerability that could have been exploited by hackers to hijack Microsoft Teams accounts by sending specially crafted links …
Context & Ripple Effects
This is the second time in under two years that Microsoft has had to close an account-hijacking path into its own identity stack — after a misconfigured domain let researchers hijack any Office login in late 2018 — and the first such flaw found in Teams itself, which by April 2020 has become critical infrastructure for remote work.
Teams' security record is already under scrutiny: in September, Vectra disclosed that Teams stores authentication tokens in unencrypted plaintext, with Microsoft declining to fix it on the grounds that exploitation requires network access. A link-and-GIF vector that needs no network position raises the bar on what attackers can do against the same platform.
First-order effects
- Organizations running Teams must deploy the patch to close a channel where a single clicked malicious link or GIF could hand over an authenticated session — no credentials phished, no malware installed.
Second-order effects
- Security teams will treat Teams as an attack surface in its own right rather than just a productivity tool, adding it to phishing-awareness and endpoint monitoring alongside email — and researchers now have a demonstrated template for probing the app's message-rendering pipeline.
Third-order effects
- If collaboration suites keep producing account-takeover flaws through content rendering, enterprise buyers will start weighing messaging apps' security track records as heavily as features, pushing vendors toward hardened-by-default handling of user-supplied media.
The trend: Collaboration platforms are displacing email as the primary account-hijacking vector, forcing Microsoft to harden Teams' content handling the way it once hardened Office logins.