Cyber Security

Black Basta Ransomware Uses Microsoft Teams to Deploy Zbot Malware

The Black Basta ransomware group has advanced its tactics, leveraging Microsoft Teams to execute targeted cyberattacks. These attackers employ social engineering techniques to deliver malware such as Zbot, DarkGate, and custom payloads, increasing their effectiveness in targeting Windows users.

How the Attack Works

The campaign begins with threat actors using Microsoft Teams to contact targets. They pose as IT personnel and exploit phishing tactics to convince users to install remote management tools such as QuickAssist, TeamViewer, or AnyDesk. Once the victim grants access, attackers initiate malware downloads to compromise the user’s credentials and infiltrate organizational assets.

Key tactics include:

• Social Engineering: Threat actors use authentic-looking display names on Teams to gain the target’s trust.
• Remote Management Tools: Attackers install software to establish a foothold in the target’s system.
• Credential Harvesting: Using customized DLL payloads to steal login information and VPN configurations.
• Payload Delivery: The attackers deploy advanced malware like Zbot, which uses RSA encryption for secure command-and-control communications, and DarkGate, a multifunctional toolkit for data theft and privilege escalation.

Notable Techniques

• Reverse Shells: Operators utilize Windows’ OpenSSH client to execute commands remotely.
• QR Codes: In some cases, attackers distribute QR codes, likely to bypass multi-factor authentication (MFA).
• Cobalt Strike Beacons: For further penetration, the group uses PowerShell commands and loaders for Cobalt Strike and other malicious payloads.

Recommendations for Protection

1. Restrict External Communications: Limit external users’ ability to contact employees via Microsoft Teams.
2. Standardize Remote Management Tools: Regulate the use of authorized tools to minimize risks.
3. User Training: Educate employees to recognize phishing attempts and social engineering techniques.
4. Secure VPN Access: Strengthen VPN configurations and enforce MFA to protect organizational networks.

The sophistication of Black Basta’s methods underscores the need for robust cybersecurity measures. By exploiting trusted platforms like Microsoft Teams, the group increases its chances of success, emphasizing the importance of proactive threat detection and response.