CISA orders agencies impacted by Microsoft hack to mitigate risks

CISA has issued a new emergency directive ordering U.S. federal agencies to address risks resulting from the breach of multiple Microsoft corporate email accounts by the Russian APT29 hacking group.

Emergency Directive 24-02 was issued to Federal Civilian Executive Branch (FCEB) agencies on April 2. It requires them to investigate potentially affected emails, reset any compromised credentials (if any), and take measures to secure privileged Microsoft Azure accounts.

CISA says Russian Foreign Intelligence Service (SVR) operatives now use information stolen from Microsoft's corporate email systems, including the authentication details shared between Microsoft and its customers by email, to gain access to certain customer systems.

"This Emergency Directive requires immediate action by agencies to reduce risk to our federal systems. For several years, the U.S. government has documented malicious cyber activity as a standard part of the Russian playbook; this latest compromise of Microsoft adds to their long list," said CISA Director Jen Easterly on Thursday.

"We will continue efforts in collaboration with our federal government and private sector partners to protect and defend our systems from such threat activity."

Federal agencies' emails stolen

Microsoft and the U.S. cybersecurity agency have already notified all federal agencies whose email correspondence with Microsoft was detected as exfiltrated by the Russian hackers.

CISA's new emergency directive is the first time the U.S. government confirmed that federal agency emails were exfiltrated in the January Microsoft Exchange breaches.

CISA has now ordered affected agencies to identify the full content of the agency correspondence with compromised Microsoft accounts and perform a cybersecurity impact analysis by April 30, 2024.

Those who detect signs of authentication compromises are required to:

1. Take immediate remediation action for tokens, passwords, API keys, or other authentication credentials known or suspected to be compromised.
2. For any known or suspected authentication compromises identified through action 1 by April 30, 2024:
   1. Reset credentials in associated applications and deactivate associated applications that are no longer of use to the agency.
   2. Review sign-in, token issuance, and other account activity logs for users and services whose credentials were suspected or observed as compromised for potential malicious activity.

Even though ED 24-02 requirements exclusively apply to FCEB agencies, the exfiltration of Microsoft corporate accounts may impact other organizations, which are urged to seek guidance from their respective Microsoft account teams.

It's also essential that all organizations, regardless of the impact, adopt strict security measures, including using strong passwords, enabling multifactor authentication (MFA) whenever possible, and refraining from sharing unprotected sensitive information via unsecured channels.

APT29's Microsoft hacks

In January, Microsoft revealed that APT29 hackers (also tracked as Midnight Blizzard and NOBELIUM) had breached its corporate email servers following a password spray attack that led to the compromise of a legacy non-production test tenant account.

The company later disclosed that the test account didn't have MFA enabled, allowing the hackers to access Microsoft's systems.

The account also had access to an OAuth application with elevated access to Microsoft's corporate environment, which let the attackers access and steal data from corporate mailboxes. These email accounts belonged to Microsoft's leadership team members and an undisclosed number of employees in the company's cybersecurity and legal departments.

APT29 gained notoriety after the 2020 SolarWinds supply chain attack, which resulted in the breach of some U.S. federal agencies and numerous companies, including Microsoft.

Microsoft later confirmed the attack allowed the Russian hacking group to steal source code for some Azure, Intune, and Exchange components.

In June 2021, the APT29 hackers again breached a Microsoft corporate account, providing them access to customer support tools.