The newly identified ‘Fog‘ ransomware variant is specifically targeting US businesses, primarily in the education sector with 80% of the attacks, and the recreation sector accounting for the remaining 20%. The attackers gain access to the victims’ systems through compromised VPN credentials and administrator accounts, using these to establish RDP connections to Windows servers. They disable Windows Defender, erase backups, and encrypt critical data, demanding ransom through a consistent payload with unique chat codes for each victim.
Arctic Wolf Labs began monitoring this ransomware on May 2, 2024, noting the use of credential stuffing to facilitate lateral movement within the affected networks. In all observed instances, the attackers deployed PsExec and utilized RDP/SMB to access their targeted hosts. The threat actors consistently left ransom notes and used the same functional ransomware payload, focusing on encrypting VMDK files in VM storage and erasing Veeam backups.
The lack of additional dark web presence, such as a data leak site, suggests that the threat actors are prioritizing quick financial returns over more elaborate attacks involving data exfiltration. This behavior implies a financially motivated group targeting vulnerable sectors, with a primary focus on education institutions.
Despite the familiar tactics, these attacks underscore the importance of comprehensive cybersecurity measures, including defense-in-depth strategies and secure, off-site backup systems. Organizations must remain vigilant and proactive in their cybersecurity efforts to prevent and mitigate the impact of such ransomware threats.
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