Zero-Click Wormable RCE Vulnerability Reported in Microsoft Teams

  • A zero-click on remote code execution (RCE) bug in Microsoft Groups desktop applications could have permitted an adversary to execute arbitrary code by basically sending a specially-crafted chat information and compromise a target’s technique.

    The issues were being noted to the Windows maker by Oskars Vegeris, a security engineer from Evolution Gaming, on August 31, 2020, in advance of they were addressed at the stop of Oct.

    “No consumer conversation is necessary, exploit executes upon looking at the chat message,” Vegeris stated in a technical produce-up.

    The end result is a “comprehensive loss of confidentiality and integrity for stop people — entry to personal chats, documents, internal network, personal keys and personal info outside the house MS Teams,” the researcher added.

    Even worse, the RCE is cross-platform — influencing Microsoft Teams for Windows (v1.3.00.21759), Linux (v1.3.00.16851), macOS (v1.3.00.23764), and the web ( — and could be manufactured wormable, this means it could be propagated by quickly reposting the destructive payload to other channels.

    This also indicates the exploit can be passed on from a person account to a whole group of buyers, therefore compromising an total channel.

    To accomplish this, the exploit chain strings with each other a cross-web page scripting (XSS) flaw current in the Groups ‘@mentions’ functionality and a JavaScript-based RCE payload to submit a harmless-looking chat information that contains a consumer mention possibly in the type of a immediate message or to a channel.

    Basically browsing the chat at the recipient’s conclusion potential customers to the execution of the payload, allowing it to be exploited to log users’ SSO tokens to local storage for exfiltration and execute any command of the attacker’s selection.

    This is not the first time this sort of RCE flaws were being observed in Groups and other organization-centered messaging apps.

    Chief among them is a different RCE vulnerability in Microsoft Groups (CVE-2020-17091) that the firm patched as component of its November 2020 Patch Tuesday last thirty day period.

    Earlier this August, Vegeris also disclosed a critical “wormable” flaw in Slack’s desktop edition that could have allowed an attacker to consider more than the technique by just sending a malicious file to another Slack person.

    Then in September, networking machines maker Cisco patched a identical flaw in its Jabber movie conferencing and messaging app for Windows that, if exploited, could allow an authenticated, distant attacker to execute arbitrary code.

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