Fog ransomware first appeared in May 2024 and within six months had become the most active ransomware operation targeting the education sector. The group's focus on schools, colleges, and universities is not coincidental -- it reflects a calculated strategy to hit organizations with weak defenses, valuable data, and strong motivation to pay.
By December 2024, Fog had claimed responsibility for over 80 attacks on educational institutions across the United States, Canada, and Europe. The speed of their operations was remarkable: the median time from initial access to encryption was just two hours, significantly faster than most ransomware groups.
Why Education
The education sector is uniquely vulnerable to ransomware for reasons that go beyond tight budgets:
Seasonal pressure. Universities face enormous pressure at the start of academic terms. A ransomware attack in August or January -- right before classes begin -- creates urgency that commercial organizations do not face. Fog operators clearly understood this, with attack spikes correlating to academic calendars.
Flat network architectures. Most educational institutions run relatively flat networks. Student systems, administrative systems, and research networks often share infrastructure. A single point of entry provides access to everything.
Data sensitivity. Educational records include Social Security numbers, financial aid information, medical records from student health services, and research data. FERPA violations add regulatory pressure on top of operational disruption.
Decentralized IT. Universities in particular have highly decentralized IT environments. Individual departments often manage their own servers, research labs maintain independent infrastructure, and shadow IT is pervasive. This makes consistent patching nearly impossible.
The SonicWall VPN Vector
Fog's primary initial access vector throughout 2024 was exploitation of SonicWall SSL VPN vulnerabilities. SonicWall appliances are disproportionately common in the education sector because of their relatively low cost and historical presence in the market.
The specific vulnerabilities exploited include:
- CVE-2024-40766: A critical access control vulnerability in SonicOS allowing unauthenticated access
- Older, unpatched vulnerabilities in SonicWall SMA 100 series appliances
The attack pattern was consistent:
- Automated scanning identified internet-facing SonicWall appliances
- Exploitation provided VPN credentials or direct access
- The attacker used the VPN connection to access internal networks
- Within minutes, they began lateral movement using compromised Active Directory credentials
- Data exfiltration started immediately, with encryption following within two hours
The speed of these operations suggests a high degree of automation. Fog operators likely had pre-built toolkits for each phase of the attack, allowing rapid execution once initial access was established.
Supply Chain Dimensions
While Fog's primary vector is direct exploitation, several incidents revealed supply chain dimensions to their operations.
Compromised IT Service Providers
At least three Fog incidents in 2024 involved compromise of regional IT service providers that manage technology for multiple school districts. In one case, a single provider compromise led to simultaneous attacks on seven school districts in the same state.
The pattern mirrors what we see with other ransomware groups targeting MSPs, but with a specific focus on education-sector service providers. These providers often manage SonicWall appliances for multiple districts, creating a single point of failure.
Software Vendor Exploitation
One incident involved the compromise of a student information system vendor's support portal. The attackers used the vendor's remote support capabilities to access client environments. While this appeared to be an opportunistic pivot rather than a planned supply chain attack, it demonstrates how interconnected the education technology ecosystem has become.
Shared Infrastructure Risks
Educational consortia and state-level shared services create additional supply chain risks. When multiple institutions share authentication infrastructure, email systems, or learning management platforms, a compromise of the shared service affects all participants.
Operational Speed
Fog's operational tempo distinguishes it from most ransomware groups. While the average ransomware dwell time across all sectors is measured in days or weeks, Fog consistently achieved encryption within hours of initial access.
This speed serves multiple purposes:
- Reduces detection window. Security teams have less time to notice and respond to the intrusion.
- Overwhelms incident response. By the time the attack is noticed, encryption is already complete.
- Minimizes forensic artifacts. Short dwell times mean fewer logs and traces to analyze.
The tradeoff is that Fog's data exfiltration is less thorough than groups that spend weeks inside a network. They grab what they can quickly -- primarily from file shares and email servers -- rather than conducting comprehensive data theft.
Impact on the Education Ecosystem
The concentration of attacks on education has had ripple effects beyond individual institutions:
Cyber insurance costs have spiked. Several insurance carriers have increased premiums or reduced coverage for educational institutions. Some have added specific exclusions for ransomware attacks originating from unpatched VPN appliances.
State-level responses. Multiple states have allocated emergency funding for school district cybersecurity improvements in response to Fog and similar attacks. These programs typically focus on MFA deployment, backup modernization, and network segmentation.
Vendor accountability. The repeated exploitation of SonicWall appliances has prompted some school districts to file claims against the vendor and their resellers, arguing that the devices were sold without adequate security hardening guidance.
Defense Strategies for Education
Given the constraints of educational environments, pragmatic defense strategies include:
Patch VPN appliances immediately. This sounds obvious, but the persistence of SonicWall exploitation indicates it is not happening. Automated patch management for network appliances should be a top priority.
Implement network segmentation. Separate student networks, administrative systems, and research environments. Even basic VLAN segmentation significantly limits lateral movement.
Deploy MFA everywhere. Fog's speed depends on having valid credentials for lateral movement. MFA on VPN connections, administrative portals, and remote desktop creates friction that slows the attack.
Maintain offline backups. Given Fog's speed, detection before encryption is unlikely. Offline, immutable backups are the most reliable recovery mechanism.
Monitor VPN connections. Alert on VPN connections from unusual locations, at unusual times, or from devices that do not match known profiles. This is the earliest detection opportunity for Fog's attack pattern.
Audit service provider access. Understand what access your IT service providers have and implement monitoring on those connections.
How Safeguard.sh Helps
Safeguard.sh addresses the education sector's supply chain security challenges through automated SBOM generation that catalogs every software component running in your environment -- from the SonicWall firmware version on your VPN appliances to the dependencies in your student information system. The platform's continuous vulnerability monitoring ensures that critical CVEs like those exploited by Fog are flagged immediately, with prioritization based on actual exploitability rather than just CVSS scores. For educational consortia and shared service providers, Safeguard's multi-tenant architecture provides visibility across all connected institutions without requiring each one to maintain its own security team. The platform's policy engine can enforce patching SLAs that ensure network appliances like VPN concentrators are updated within hours of critical patch releases, directly addressing the primary vector that Fog exploits.