In March 2022, a new malware loader was discovered by Google Threat Analysis Group. ​​This loader is named Bumblebee because of its unique user agent, “Bumblebee,” that is used as part of the communication with the command and control server (C2). In this Threat Analysis report, the Cybereason Global Security Operations Center (GSOC) team have analysed a case that involved a Bumblebee Loader infection. Researchers describe in detail the attack chain from the initial Bumblebee infection to the compromise of the entire network.

Key findings include:

• User-Driven Execution: The majority of the infections with Bumblebee we have observed started by end-users executing LNK files which use a system binary to load the malware. Distribution of the malware is done by phishing emails with an attachment or a link to the malicious archive containing Bumblebee.
• Intensive Reconnaissance and Data Exfiltration: Bumblebee operators conduct intensive reconnaissance activities and redirect the output of executed commands to files for exfiltration.
• Active Directory Compromise: The attackers compromised Active Directory and leveraged confidential data such as users’ logins and passwords for lateral movement. The time it took between initial access and Active Directory compromise was less than two days.
• Under Active Development: Cybereason GSOC has observed threat actors transitioning from BazarLoader, Trickbot, and IcedID to Bumblebee, which seems to be in active development and generally the loader of choice for many threat actors.
• Critical Severity: Attacks involving Bumblebee must be treated as critical. Based on GSOC findings, the next step for the threat actors is ransomware deployment, and this loader is known for ransomware delivery.