Russian APT Group Unveils Novel "Nearest Neighbor Attack" Targeting Wi-Fi Networks

Russian APT Group Unveils Novel "Nearest Neighbor Attack" Targeting Wi-Fi NetworksIn a groundbreaking discovery, cybersecurity firm Volexity has uncovered a sophisticated attack technique employed by a Russian Advanced Persistent Threat (APT) group known as GruesomeLarch (also known as APT28, Forest Blizzard, Sofacy, and Fancy Bear). This new method, dubbed the "Nearest Neighbor Attack," involves leveraging Wi-Fi networks of organizations in close proximity to the intended target.

Key Takeaways

• GruesomeLarch utilized nearby Wi-Fi networks to gain covert access to their primary target.

• The attack primarily employed living-off-the-land techniques.

• A zero-day privilege escalation was used to further gain access.

• The operation targeted Ukrainian-related work and projects, occurring just before the Russian invasion of Ukraine.

The Attack Methodology

The Nearest Neighbor Attack involves a multi-step process:

1. Credential Harvesting: The attackers used password-spray attacks against public-facing services to obtain valid credentials.

2. Exploiting Wi-Fi Vulnerabilities: While multi-factor authentication (MFA) protected internet-facing services, the enterprise Wi-Fi network only required a username and password.

3. Compromising Nearby Organizations: Unable to physically connect to the target's Wi-Fi, the attackers breached organizations in close proximity to their main target.

4. Lateral Movement: Within these compromised organizations, the attackers sought out dual-homed systems (connected to both wired and wireless networks).

5. Wi-Fi Hijacking: Using the compromised systems, the attackers connected to the target organization's Wi-Fi network, effectively bridging the physical gap.

Investigation Challenges

Volexity faced several obstacles during their investigation:

• The attacker used anti-forensic techniques, including securely erasing files with the Cipher.exe utility.

• Initial network logs provided little information about the attacker's activities.

• The investigation went cold for a period before the attacker resurfaced.

Breakthrough and Resolution

The investigation gained momentum when Volexity accessed the organization's wireless controller logs. This led to the discovery of the attacker's IP address, authenticated domain user, and MAC address.

Further analysis revealed:

• The attacker was connecting from an organization across the street from the target.

• Multiple nearby organizations were compromised to create a chain of Wi-Fi and VPN connections.

• A final attempt to regain access through the guest Wi-Fi network was thwarted.

Implications and Mitigation

This new attack vector highlights the importance of:

1. Implementing MFA on all network access points, including Wi-Fi.

2. Monitoring and securing nearby Wi-Fi networks.

3. Enhancing logging and visibility across all network segments.

4. Regularly auditing and updating access controls.

The Nearest Neighbor Attack serves as a stark reminder of the evolving threat landscape and the need for comprehensive security measures that extend beyond an organization's immediate perimeter.