Active Reconnaissance Campaign Targets SonicWall Firewalls Through Commercial Proxy Infrastructure

GreyNoise observed 84,142 scanning sessions targeting SonicWall SonicOS infrastructure between February 22 and February 25, 2026. The activity originated from 4,305 unique IP addresses across 20 autonomous systems, with three operationally distinct infrastructure clusters executing coordinated VPN enumeration. Ninety-two percent of sessions probed a single API endpoint to determine whether SSL VPN is enabled — the prerequisite check before credential attacks. A commercial proxy service delivered 32% of campaign volume through 4,102 rotating exit IPs in two surgical bursts totaling 16 hours. CVE exploitation was negligible, confirming this as systematic attack surface mapping.

SonicWall SSL VPN is one of the most documented initial access vectors for ransomware. Akira and Fog ransomware groups have repeatedly demonstrated that compromised SonicWall VPN credentials lead to full encryption in under four hours — with dwell times as short as 55 minutes. Five of seven SonicWall CVEs relevant to this attack surface appear in CISA's Known Exploited Vulnerabilities catalog, with four having documented ransomware use. The reconnaissance GreyNoise observed is the precursor phase — systematic target mapping that precedes exploitation.

Since March 2023, Akira alone has compromised at least 250 organizations and generated an estimated $244 million in ransomware proceeds, with 75% of SonicWall VPN intrusions attributed to Akira and 25% to Fog. More than 430,000 SonicWall firewalls are publicly exposed on the internet, with over 25,000 SSL VPN devices vulnerable to critical flaws and 20,000 running firmware that is no longer supported.