Volexity’s recent discovery of a Russian nation-state group breaching a victim organization by exploiting nearby Wi-Fi networks and a known vulnerability to gather intelligence on Ukraine has raised significant concerns in the cybersecurity community. The attack, attributed to the notorious group known as GruesomeLarch or Fancy Bear, showcased a new attack vector dubbed the “Nearest Neighbor Attack.”
During an extensive incident response investigation for an undisclosed organization in Washington, D.C., Volexity researchers uncovered the sophisticated techniques employed by GruesomeLarch. The attack, which coincided with Russia’s invasion of Ukraine, involved the threat actors utilizing neighborhood Wi-Fi networks to spy on the victim organization, referred to as “Organization A” in the report.
Volexity founder Steven Adair highlighted the innovative nature of the attack during the presentation of the research at Cyberwarcon 2024. The threat actors, located thousands of miles away from the victim organization, employed a strategy of compromising multiple organizations in close proximity to their target. By leveraging password spray attacks to obtain valid credentials, GruesomeLarch was able to breach the targeted organization’s enterprise network Wi-Fi, which lacked multi-factor authentication (MFA).
The attackers then proceeded to move laterally within the compromised organizations, ultimately gaining access to the victim organization’s network. This lateral movement was facilitated by compromising a dual-homed system at a nearby organization, connecting to the victim organization’s enterprise Wi-Fi network.
The report highlighted critical security lapses in the victim organization’s infrastructure, including the absence of MFA on the Wi-Fi network and VPN. Despite initial remediation efforts, GruesomeLarch persisted in compromising the organization’s guest Wi-Fi network to regain access to high-value data.
In addition to leveraging living-off-the-land (LOTL) techniques, the threat actors exploited a Microsoft Windows print spooler vulnerability for data exfiltration. Volexity linked this exploitation to GruesomeLarch’s previous activities tracked by Microsoft as Forest Blizzard. The report emphasized the importance of securing Wi-Fi networks and implementing robust security controls to mitigate such sophisticated attacks.
Volexity recommended that organizations develop custom detection tools, monitor data exfiltration from internet-facing services, and segregate Wi-Fi and Ethernet-wired networks to enhance network security. The Nearest Neighbor Attack underscored the evolving tactics employed by advanced threat actors and the critical need for proactive cybersecurity measures to safeguard against such threats.
As the cybersecurity landscape continues to evolve, organizations must remain vigilant and continuously assess their security posture to defend against sophisticated nation-state threats like GruesomeLarch. By learning from incidents such as this one, companies can better protect their sensitive data and networks from malicious actors seeking to exploit vulnerabilities for nefarious purposes.