Unless You Consider Excel Passwords to be Real Passwords

I see that some web sites have picked up the penetration test story about using Microsoft 365 Copilot to extract sensitive information from SharePoint. The May 14 Forbes.com story is an example. The headline of “New Warning — Microsoft Copilot AI Can Access Restricted Passwords” is highly misleading.

Unfortunately, tech journalists and others can rush to comment without thinking an issue through, and that’s what I fear has happened in many of the remarks I see in places like LinkedIn discussions. People assume that a much greater problem exists when if they would only think things through, they’d see the holes in the case being presented.

Understanding the Assumptions made by the Penetration Test

As I pointed out in a May 12 article, the penetration test was interesting (and did demonstrate just how weak Excel passwords are). However, the story depends on three major assumptions:

• Compromise: The attacker has control of an Entra ID account with a Microsoft 365 Copilot license. In other words, the target tenant is compromised. In terms of closing off holes for attackers to exploit, preventing access is the biggest problem in the scenario. All user accounts should be protected with strong multifactor authentication like the Microsoft authenticator app, passkeys, or FIDO-2 keys. SMS is not sufficient, and basic authentication (just passwords) is just madness.
• Poor tenant management: Once inside a tenant and using a compromised account, Microsoft 365 Copilot will do what the attacker asks it to do, including finding sensitive information like a file containing passwords. However, Copilot cannot find information that is unavailable to the signed-in user. If the tenant’s SharePoint Online deployment is badly managed without well-planned and well-managed access controls, then Copilot will happily find anything that the user’s access allows it to uncover. This is not a problem for Copilot: it is a failure of tenant management that builds on the first failure to protect user accounts appropriately.
• Failure to deploy available tools: Even in the best-managed SharePoint Online deployment, users can make mistakes when configuring access, Users can also follow poor practice, such as storing important files in OneDrive for Business rather than SharePoint Online. But tenants with Microsoft 365 Copilot licenses can mitigate against user error with tools available to them such as Restricted Content Discovery (RCD) and the DLP policy for Microsoft 365 Copilot. The latter requires the tenant to deploy sensitivity labels too, but that’s part of the effort required to protect confidential and sensitive information.

I’m sure any attacker would love to find an easily-compromised tenant where they can gain control over accounts that have access to both badly managed SharePoint Online sites that hold sensitive information and Microsoft 365 Copilot to help the attackers find that information. Badly-managed and easily-compromised Microsoft 365 tenants do exist, but it is my earnest hope that companies who invest in Microsoft 365 Copilot have the common sense to manage their tenants properly.

Uploading SharePoint and OneDrive Files to ChatGPT

Personally speaking, I’m much more concerned about users uploaded sensitive or confidential information to OpenAI for ChatGPT to process. The latest advice from OpenAI is how the process works for their Deep Research product. Users might like this feature because they can have their documents processed by AI. However, tenant administrators and anyone concerned with security or compliance might have a different perspective.

I covered the topic of uploading SharePoint and OneDrive files to ChatGPT on March 26 and explained that the process depends on an enterprise Entra ID app (with app id e0476654-c1d5-430b-ab80-70cbd947616a) to gain access to user files. Deep Research is different and its connector for SharePoint and OneDrive is in preview, but the basic principle is the same: a Graph-based app uploads files for ChatGPT to process. If that app is blocked (see my article to find out how) or denied access to the Graph permission needed to access files, the upload process doesn’t work.

Set Your Priorities

I suggest that it’s more important to block uploading of files from a tenant to a third-party AI service where you don’t know how the files are managed or retained. It certainly seems like a more pressing need than worrying about the potential of an attacker using Microsoft 365 Copilot to run riot over SharePoint, even if a penetration test company says that this can happen (purely as a public service, and not at all to publicize their company).

At least, that’s assuming user accounts are protected with strong multifactor authentication…