Microsoft 365 Copilot Business Chat Information Disclosure Vulnerabilities

Multiple information disclosure vulnerabilities exist in Microsoft 365 Copilot Business Chat. An anonymous, remote attacker can exploit these flaws without authentication to gain access to sensitive information. The exact nature of the vulnerabilities and the specific information that can be disclosed are not detailed in the source, but successful exploitation could expose proprietary data, internal communications, or other confidential material accessible through the Copilot Business Chat service. Defenders need to identify and mitigate potential attack vectors targeting Copilot Business Chat to prevent unauthorized access to organizational data.

Attack Chain

1. An anonymous, remote attacker identifies accessible Microsoft 365 Copilot Business Chat instances.
2. The attacker crafts a malicious request or series of requests designed to exploit the information disclosure vulnerabilities within Copilot Business Chat.
3. The attacker sends the crafted requests to the vulnerable Copilot Business Chat endpoint.
4. Copilot Business Chat processes the malicious request without proper validation or authorization checks.
5. Due to the vulnerabilities, Copilot Business Chat inadvertently discloses sensitive information to the attacker in the response.
6. The attacker captures and analyzes the disclosed information.
7. The attacker repeats the process to gather more information or pivots to other attack vectors.

Impact

Successful exploitation of these vulnerabilities could lead to the disclosure of sensitive business information. This includes internal communications, proprietary data, and other confidential material accessible through Microsoft 365 Copilot Business Chat. The potential impact ranges from exposing sensitive internal discussions to revealing trade secrets, which could significantly harm the organization’s competitive advantage and reputation.

Recommendation

• Monitor web server logs for suspicious activity targeting Microsoft 365 Copilot Business Chat (see example Sigma rule below).
• Audit Microsoft 365 Copilot Business Chat configurations and access controls to ensure proper security measures are in place.
• Apply any available patches or updates released by Microsoft for Microsoft 365 Copilot Business Chat to address these vulnerabilities when available.