The Cybersecurity and Infrastructure Security Agency (CISA), the Federal Bureau of Investigation (FBI), and the National Security Agency (NSA) this week published a joint advisory to warn organizations of an increased threat posed by the BlackMatter ransomware gang.
Active since July 2021, BlackMatter is believed to be the successor of DarkSide, a ransomware-as-a-service (RaaS) that shut down operations in May 2021. DarkSide was responsible for multiple high-profile ransomware attacks.
According to the joint advisory, the BlackMatter ransomware has already targeted multiple critical infrastructure entities in the United States, including two organizations in the food and agriculture sector.
In a typical BlackMatter attack, the ransomware operators employ compromised credentials and abuse the Lightweight Directory Access Protocol (LDAP) and Server Message Block (SMB) protocol to access an organization’s Active Directory (AD) and compromise all hosts and shared drives on the network.
“BlackMatter actors use a separate encryption binary for Linux-based machines and routinely encrypt ESXi virtual machines. Rather than encrypting backup systems, BlackMatter actors wipe or reformat backup data stores and appliances,” the agencies said.
Legitimate tools and attacker-created accounts are abused for remote, persistent access to the compromised environment, and the threat actors also attempt to steal victim’s data to use for extortion.
To mitigate the threat posed by BlackMatter and other ransomware families, organizations of all types are advised to implement detection signatures, use strong passwords on all accounts, implement multi-factor authentication, keep systems updated, restrict user access to resources, and use firewalls and network segmentation.
The agencies said network admins should also keep all data backed up offline and make sure that backups are encrypted, and implement tools to detect abnormal activity within their environments, in addition to implementing a ransomware response plan.
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