Unveiling the Nearest Neighbor Attack

In the ever-evolving landscape of cybersecurity, new threats emerge regularly, challenging organizations to stay one step ahead. Recently, researchers from Volexity uncovered a particularly alarming method employed by Russian hackers, known as the Nearest Neighbor Attack. This sophisticated technique allowed the threat group, often referred to as GruesomeLarch (or APT28/Fancy Bear), to breach a U.S. organization by exploiting nearby Wi-Fi networks. Let’s dive into how this attack works and what organizations can do to protect themselves.

What is the Nearest Neighbor Attack?

The Nearest Neighbor Attack was first detected on February 4, 2022, during an investigation into a server compromise at a Washington, D.C.-based organization involved in projects related to Ukraine. Initially, the attackers gained access credentials through password-spraying attacks targeting public-facing services. However, they hit a roadblock when multi-factor authentication (MFA) measures prevented them from accessing the enterprise Wi-Fi network directly over the internet. To bypass these defenses, the hackers turned their attention to nearby organizations within Wi-Fi range. By compromising these networks, they searched for dual-homed devices—systems that can connect to both wired and wireless networks. This clever pivot allowed them to connect to the target's enterprise Wi-Fi network without triggering MFA protections.

How Did the Attack Unfold?

The attackers used their access to multiple organizations to create a daisy-chain connection using valid credentials. They identified devices capable of connecting to several wireless access points near the victim's conference room. Once they gained access through a compromised dual-homed system, they employed remote desktop protocols to move laterally within the target network, seeking sensitive data related to Ukrainian projects. Volexity reported that the attackers used living-off-the-land techniques, meaning they utilized legitimate tools and scripts found within the victim's environment to minimize detection. For example, they executed a script named servtask.bat to dump Windows registry hives and exfiltrate data without raising alarms.

Key Vulnerabilities Exploited

The success of this attack hinged on several vulnerabilities:

• Lack of MFA on Wi-Fi Networks: The absence of MFA on enterprise Wi-Fi allowed attackers to exploit it freely once they gained access through nearby organizations.

• Insufficient Isolation of Guest Networks: The attackers were able to compromise a guest Wi-Fi network that was not fully isolated from corporate resources, allowing them to regain access after initial remediation efforts seemed successful.

• Exploitation of Known Vulnerabilities: The hackers exploited a vulnerability in the Windows Print Spooler service (CVE-2022-38028) for data exfiltration, facilitating their lateral movement within the network.

Overview of the Windows Print Spooler Vulnerability - CVE-2022-38028

https://msrc.microsoft.com/update-guide/en-US/advisory/CVE-2022-38028 |

Conclusion

As cyber threats become increasingly sophisticated, understanding and mitigating risks associated with network access is crucial for organizations aiming to protect sensitive information from state-sponsored actors like Gruesome Larch. The Nearest Neighbor Attack highlights the need for robust cybersecurity measures in an interconnected world. By implementing stronger security protocols and remaining vigilant, organizations can better safeguard themselves against these emerging threats. Stay informed and proactive—your organization's security depends on it!