Incident Alert (Aug 31, 2025): A new malware-as-a-service (MaaS) campaign—“PhantomFlow”—has emerged, delivering a fileless loader via PowerShell through compromised Azure Function endpoints. Initial detection points to stealthy ransomware payloads being deployed across healthcare and manufacturing networks.
Key Details:
- Attack Vector: Azure Function apps abused for persistent payload execution.
- Payload: Fileless PowerShell loader using memory-resident obfuscation, avoiding disk writes.
- Targets Observed: Healthcare systems in North America and manufacturing environments in Europe.
- TTP Highlights:
- Leveraging compromised Azure credentials stored in Git repos.
- Post-compromise, lateral movement via SMB session hijacking and in-memory execution.
- Final-stage payload is a ransomware wrapper that triggers both encryption and data exfil via SFTP.
Severity: High
- Novel vector: the use of Azure serverless functions as malware launch pads is a first-of-its-kind attack technique.
- High stealth: fileless design and memory-only components make detection by traditional AV extremely difficult.
CyberDudeBivash Recommended Actions:
- Audit Azure Functions & Logging
- Immediately review Function app activity logs for anomalous script execution.
- Rotate and secure all Function credentials— do not store secrets in GitHub.
- Deploy Memory-Based Detection
- Utilize EDR that supports PowerShell script tracking, AMSI bypass detection, and memory-only persistence.
- Harden Azure Environment
- Lock down managed identities & access controls for Function apps.
- Enforce network lockdowns—restrict outbound ports like SMB and SFTP from serverless environments.
- Infra Threat Hunting
- Look for in-memory anomalies, unexpected Azure exec logs, and unusual SFTP exfil attempts.
- Contain & Notify
- If detected, isolate affected Function apps.
- Inform Azure Security Center and start incident response playbooks immediately.
CyberDudeBivash Insight:
PhantomFlow demonstrates a troubling shift: adversaries weaponizing cloud-native infrastructures—not just VMs or containers—but serverless compute. This elevates the threat posture across all DevOps-driven organizations using Azure or similar platforms.
CyberDudeBivash is formally monitoring this campaign and preparing a dedicated mitigation playbook (released within 48 hours) to secure azure-native pipelines.
Stay tuned for our ThreatWire Flash Edition, and share this alert across SOC/SecurityOps channels.
— CyberDudeBivash (Threat Intel Lead)
#CyberDudeBivash #FlashAlert #FilelessMalware #AzureFunctions #ThreatIntel
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