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Microsoft Azure cloud vulnerability is the ‘worst you can imagine’

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Thousands of companies using Azure warned that their data has been exposed for years

Another day, another major Microsoft vulnerability.
Illustration by Alex Castro / The Verge

Microsoft has warned thousands of its Azure cloud computing customers, including many Fortune 500 companies, about a vulnerability that left their data completely exposed for the last two years.

A flaw in Microsoft’s Azure Cosmos DB database product left more than 3,300 Azure customers open to complete unrestricted access by attackers. The vulnerability was introduced in 2019 when Microsoft added a data visualization feature called Jupyter Notebook to Cosmos DB. The feature was turned on by default for all Cosmos DBs in February 2021.

A listing of Azure Cosmos DB clients includes companies like Coca-Cola, Liberty Mutual Insurance, ExxonMobil, and Walgreens, to name just a few.

“This is the worst cloud vulnerability you can imagine,” said Ami Luttwak, Chief Technology Officer of Wiz, the security company that discovered the issue. “This is the central database of Azure, and we were able to get access to any customer database that we wanted.”

Despite the severity and risk presented, Microsoft hasn’t seen any evidence of the vulnerability leading to illicit data access. “There is no evidence of this technique being exploited by malicious actors,” Microsoft told Bloomberg in an emailed statement. “We are not aware of any customer data being accessed because of this vulnerability.” Microsoft paid Wiz $40,000 for the discovery, according to Reuters. In an update posted to the Microsoft Security Response Center, the company said its forensic investigation included looking through logs to find any current activity or similar events in the past. “Our investigation shows no unauthorized access other than the researcher activity,” said Microsoft.

In a detailed blog post, Wiz says that the vulnerability introduced by Jupyter Notebook allowed the company’s researchers to gain access to the primary keys that secured the Cosmos DB databases for Microsoft customers. With said keys, Wiz had full read / write / delete access to the data of several thousand Microsoft Azure customers.

Wiz says that it discovered the issue two weeks ago and Microsoft disabled the vulnerability within 48 hours of Wiz reporting it. However, Microsoft can’t change its customers’ primary access keys, which is why the company emailed Cosmos DB customers to manually change their keys in order to mitigate exposure.

Today’s issue is just the latest security nightmare for Microsoft. The company had some of its source code stolen by SolarWinds hackers at the end of December, its Exchange email servers were breached and implicated in ransomware attacks in March, and a recent printer flaw allowed attackers to take over computers with system-level privileges. But with the world’s data increasingly moving to centralized cloud services like Azure, today’s revelation could be the most troubling development yet for Microsoft.

Updated August 27th, 6:49PM ET: Added update from the MSRC.