Pierluigi Paganini December 10, 2019

Microsoft revealed that 44 million Microsoft Azure AD and Microsoft Services accounts were vulnerable to account hijacking.

Microsoft discovered that 44 million Microsoft Azure AD and Microsoft Services accounts were vulnerable to account hijacking because of using of compromised passwords.

Experts from the Microsoft threat research team analyzed a database containing 3 billion leaked credentials from different security breaches.

“The Microsoft identity threat research team checks billions of credentials obtained from different breaches (from multiple sources, including law enforcement and public databases) to look for compromised credentials in the Microsoft systems.” reads the post published by Microsoft. “As you can see on the right, so far, in 2019* the threat research team checked over 3 Billion credentials and found a match for over 44 million Azure AD and Microsoft Services Accounts.”

For each credential in the database belonging to its users, Microsoft forced a password reset, Microsoft recommends users to use MFA wherever possible.

Microsoft users’ accounts are exposed to the hack due to the bad habit of reusing passwords on multiple services and the adoption of weak passwords.

Multi-Factor Authentication (MFA) could drastically improve the security of the accounts, according to Microsoft 99.9% of identity attacks have been thwarted by enabling MFA.

“Once a threat actor gets hold of spilled credentials or credentials in the wild,” the report states, “they can try to execute a breach replay attack. In this attack, the actor tries out the same credentials on different service accounts to see if there is a match.”

Microsoft urges Azure users to turn on MFA and offers solutions to protect customers from breach replay attacks (flag users as high risk and inform the administrator to enforce a password reset).

“For the leaked credentials for which we found a match, we force a password reset. No additional action is required on the consumer side. On the enterprise side, Microsoft will elevate the user risk and alert the administrator so that a credential reset can be enforced,” concludes Microsoft.

“Microsoft also offers solutions to protect customers from breach replay attacks. This includes capabilities to flag users as high risk and inform the administrator to enforce a password reset.”

Pierluigi Paganini

(SecurityAffairs – Microsoft users, hacking)

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