Small business owner, imagine your network is encrypted in under a day. The latest threat intel shows SAMURAI-SEC ransomware moving from initial access to data theft and encryption within 24 hours.
What happened
CYFIRMA’s Weekly Intelligence Report published on Oct 23, 2026, highlights a SAMURAI-SEC ransomware campaign that gained footholds by exploiting an IIS web server. Attackers uploaded an ASP.NET web shell, established persistence over a short three-hour window, and, alarmingly, disabled endpoint security to maintain access. They then deployed the ransomware across the network, exfiltrating data in parallel. In this campaign, encryption and data theft occurred in less than 24 hours—demonstrating how quickly cybercriminals can move once they’re inside.
Why it matters
The speed of these moves matters for every organization, especially small businesses with flat networks and limited security resources. If an attacker can disable security tools and dump credentials like SAM hive or LSASS, the door to lateral movement and data theft opens wide. The takeaway is simple: your defenses must be layered, visible, and unbreakable by design.
Three defenses you can test today
- Defense 1: Protect endpoints with tamper protection and EDR
Action: In Microsoft Defender for Endpoint, turn on Tamper Protection to prevent attackers from uninstalling security tools. Steps: Open the Microsoft 365 Defender portal (security.microsoft.com) > Settings > Endpoints > Tamper Protection, switch On. Ensure Real-time protection and EDR are enabled. This helps prevent attackers from killing the very tools that detect and stop ransomware. - Defense 2: Secure the IIS edge and block web shells
Action: Patch Windows and IIS, enable a Web Application Firewall where available, and run a quick check for suspicious web shells. Quick checks: on the IIS host, open Command Prompt as Administrator and run: dir /s /b C:\inetpub\wwwroot\*.aspx | findstr /i “shell”. Remove any unfamiliar files and review web.config changes. Ensure backups are not accessible from the IIS server. - Defense 3: Protect backups and limit lateral movement
Action: Ensure backups are offline or immutable. If you’re using cloud storage, enable object-lock or immutability policies; if on-prem, keep a golden copy offline. Also implement network segmentation and MFA for admin access to reduce the chance of lateral movement.
Final thought
Ransomware campaigns are fastest when security is thin. Start with tamper protection, secure your edge servers, and verify your backup copies are safe. If you’d like a guided, low-friction defense checklist for your setup, I’m happy to help.