| QUEEN CITY CYBER CONSULTING CYBER THREAT INTELLIGENCE & INCIDENT RESPONSE BULLETIN |
| ADVISORY ID: QCCC-THREAT-2026-0818 | SEVERITY LEVEL: CRITICAL (Active Exploitation) |
| REFERENCE ADVISORY: CISA / FBI / HHS AA25-071A | RELEASE DATE: August 18, 2026 |
Threat Alert: Medusa Ransomware-as-a-Service (RaaS)
Target Audience: Security Operations Center (SOC) Analysts, Incident Responders, Threat Hunters, Systems Administrators
1. Executive Summary
On August 18, 2026, the Cybersecurity and Infrastructure Security Agency (CISA), Federal Bureau of Investigation (FBI), and the U.S. Department of Health and Human Services (HHS) issued a major joint cybersecurity advisory update (AA25-071A) regarding the Medusa Ransomware-as-a-Service (RaaS) group. Medusa operations have intensified significantly through 2026, impacting over 500 organizations worldwide with heavy opportunistic targeting across Critical Infrastructure, specifically Healthcare and Public Health (HPH), Defense Industrial Base, and Critical Manufacturing. Operating on a strict double-extortion model, Medusa combines high-speed vulnerability weaponization, out-of-band validation tooling, and living-off-the-land stealth techniques to bypass traditional defenses.
2. Emerging Threat Actor Tactics & Discoveries (2026 Update)
▪ Rapid Exploit Weaponization: Medusa affiliates demonstrate advanced agility by weaponizing newly disclosed Common Vulnerabilities and Exposures (CVEs) within 24 hours of public advisory—and in select instances, exploiting flaws up to a week prior to public vendor notification. Newly observed vectors include:
• BeyondTrust Remote Support OS Command Injection (CVE-2026-1731 | CWE-78)
• Fortra GoAnywhere MFT Deserialization of Untrusted Data (CVE-2025-10035 | CWE-502)
• ConnectWise ScreenConnect Authentication Bypass (CVE-2024-1709 | CWE-288)
• Fortinet FortiClient EMS SQL Injection (CVE-2023-48788 | CWE-89)
▪ Out-of-Band (OOB) Exploit Verification: Actors actively verify successful remote code execution before dropping full staging payloads by issuing HTTP requests to Interactsh infrastructure (e.g., victim-id.random-hash.oast.site, oast.pro, oast.fun). Defenders can use these outbound DNS/HTTP requests as high-fidelity tripwires.
▪ Initial Access Broker (IAB) Ecosystem Integration: Medusa maintains a tiered affiliate program offering initial access brokers between $100 and $1,000,000 USD per compromised environment. Core developers maintain centralized control over ransom negotiations for junior affiliates to maximize extortion yield.
▪ Advanced In-Memory Execution & Evasion: Affiliates evade EDR and signature-based antivirus using living-off-the-land binaries:
• LSASS Memory Dumping via comsvcs.dll (MiniDump) rather than executing known standalone tools.
• Gzip/Base64 In-Memory Scriptblock Cradles (powerfun.ps1 stagers) creating TLS encrypted reverse shells.
• String Slicing Obfuscation in PowerShell WebClient calls (e.g., $x = ‘D’+’Own’+’LOa’+’DfI’+’le’).
• Host Log Tampering via programmatic deletion of ConsoleHost_history.txt.
3. MITRE ATT&CK Matrix Mapping (Enterprise v19)
| TACTIC | TECHNIQUE ID | OBSERVED PROCEDURE / CONTEXT |
| Initial Access | T1190 T1566 | Exploitation of CVE-2026-1731, CVE-2025-10035, ScreenConnect, & spearphishing. |
| Execution | T1059.001 T1059.003 | Obfuscated PowerShell memory stagers, cmd.exe, and WMI query execution. |
| Credential Access | T1003.001 | LSASS credential memory dumping using rundll32.exe comsvcs.dll, MiniDump. |
| Defense Evasion | T1027.013 T1070.003 | Gzip-compressed Base64 scriptblocks; deletion of PowerShell history files. |
| Discovery | T1046 T1047 | Living-off-the-land port scanning (Ports 3389, 445, 1433) via SoftPerfect/Advanced IP. |
| Command & Control | T1105 T1071.001 | Certutil.exe ingress file transfer; OOB exploit validation via *.oast.site domains. |
4. Queen City Cyber Consulting Defensive Action Plan
✔ Perimeter Remediation Priority: Immediately identify and apply vendor patches to all perimeter-facing assets (BeyondTrust, Fortra GoAnywhere, Fortinet EMS, and ScreenConnect). Treat unpatched external appliances as active intrusion pathways.
✔ Egress DNS & Web Filtering: Implement strict outbound blocking and alerting for out-of-band exploitation frameworks, specifically subdomains of *.oast.site, *.oast.pro, and *.oast.fun at the firewall and DNS resolver levels.
✔ SIEM & Threat Hunting Logic: Deploy hunting rules for rundll32.exe calling comsvcs.dll (#24 or MiniDump exports). Enable PowerShell Script Block Logging (Event ID 4104) and flag calls utilizing IO.Compression.GzipStream or -f character replacements.
✔ Active Directory & Host Hardening: Enforce LSA Protection (RunAsPPL) and Windows Defender Credential Guard to thwart in-memory credential harvesting. Isolate administrative tier networks and restrict workstation-to-workstation SMB (445) and RDP (3389).
Queen City Cyber Consulting | Threat Intelligence & Incident Response Division
Confidential & Proprietary Advisory Document — For Defensive Operations Only
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