Microsoft Copilot Studio's Critical Flaw Exposed by Tenable Team's Discovery
In a recent finding, cybersecurity firm Tenable has uncovered a critical information disclosure vulnerability in Microsoft's Copilot Studio, a shared environment among customers. This vulnerability, if exploited, could potentially grant a malicious actor access to the internal infrastructure of Copilot Studio.
The vulnerability is due to improper handling of redirect status codes for user-configurable actions within Copilot Studio. Tenable's research team was able to exploit this flaw by retrieving managed identity access tokens from the Instance Metadata Service (IMDS), a service in the context of cloud applications that can yield potentially sensitive information for an attacker.
The vulnerability allows for a server-side request forgery (SSRF), a type of attack where an attacker can influence the application into making server-side HTTP requests to unexpected targets or in an unexpected way. In this case, an SSRF vulnerability enables an attacker to point the request to a sensitive internal resource to which the server-side application has access, even if the attacker doesn't.
This vulnerability could potentially reveal sensitive information, and grant further access to other shared resources such as a Cosmos DB, where sensitive information regarding the internals of Copilot Studio are stored. No additional information beyond the usage of Copilot Studio was required to exploit this flaw.
Jimi Sebree, a researcher at Tenable, stated that the SSRF vulnerability is a reminder of the risks that can arise when companies rush to be the first to release products in a new or rapidly expanding space. This vulnerability follows Tenable's recent discoveries of flaws in Microsoft's Azure Health Bot service, Azure Service Tags, and three vulnerabilities in the Azure API Management service.
Microsoft has confirmed that remediations for this issue were in place as of July 31, 2024, and no customer action is required. Tenable has published more technical details, including the team's findings and proof of concept, on their blog and in the technical advisory.
It is important to note that this vulnerability allowed access to Azure's Instance Metadata Service (IMDS), allowing a threat actor to obtain access tokens for the environment. This could have potentially serious implications, as it could lead to further exploits and potential data breaches.
In light of this discovery, it is crucial for organisations using Copilot Studio to ensure that their systems are up-to-date and that they have implemented the necessary security measures to protect their data. As always, vigilance and proactive security measures are key in the ever-evolving digital landscape.
