Microsoft Azure security flaw may have exposed customer data, warns CERT-In

We missed this earlier: The Indian Computer Emergency Response Team (CERT-In) issued an advisory on August 27, warning against a critical security vulnerability in Microsoft Azure’s cloud platform Cosmos DB. According to the advisory, a vulnerability in open-source platform Jupyter Notebook – used for data sharing and visualisation on Cosmos – exposed primary keys of users (which are used for administrative purposes to manage user accounts, according to a Microsoft webpage), potentially giving an attacker admin access to data stored by affected accounts.

According to CERT-In, the vulnerability could allow a hacker unrestricted access to download, delete, or manipulate any user data stored on the Cosmos DB platform.

Earlier this year, Microsoft had reportedly turned the Jupyter Notebook feature on by default for all Cosmos DB instances, including those by Fortune 500 companies Exxon Mobile and Coca-Cola. A day before the CERT-In advisory, Microsoft notified 30% of its customers who may have been impacted by the breach, Reuters reported. Cloud security firm who first alerted Microsoft about the issue, said that the vulnerability had existed for a few months before it was flagged and may have impacted all customers. Here’s an illustration of the vulnerability:


Microsoft asks customers to reset keys

On August 26, according to a blog, Microsoft mailed its customers the following statement:

Microsoft has recently become aware of a vulnerability in Azure Cosmos DB that could potentially allow a user to gain access to another customer’s resources by using the account’s primary read-write key. This vulnerability was reported to us in confidence by an external security researcher. Once we became aware of this issue on 12 August 2021, we mitigated the vulnerability immediately.

We have no indication that external entities outside the researcher had access to the primary read-write key associated with your Azure Cosmos DB account(s). In addition, we are not aware of any data access because of this vulnerability. Azure Cosmos DB accounts with a vNET or firewall enabled are protected by additional security mechanisms that prevent risk of…