NotDoor Malware Analysis Report

By Malware Analyst – CyberDudeBivash

Powered by: CyberDudeBivash
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Introduction: The Threat of NotDoor

NotDoor is a stealthy backdoor malware family observed in 2025 campaigns, targeting enterprise networks with advanced persistence techniques and encrypted C2 communications. Unlike generic backdoors, NotDoor specializes in:

Fileless execution using Windows Registry & WMI.
Evasion of endpoint detection (EDR/XDR) through DLL side-loading.
Modular payload delivery — from ransomware loaders to credential stealers.

This analysis highlights its infection lifecycle, TTPs, indicators of compromise, and CyberDudeBivash’s defensive frameworks.

Section 1: Initial Access

Phishing attachments: Malicious .docm files with VBA macros.
Exploited CVEs: VPN & RDP vulnerabilities (CVE-2025-XXXX).
Malvertising campaigns: Drive-by downloads using fake update pop-ups.

Section 2: Execution & Persistence

Fileless Execution: Uses regsvr32.exe to load malicious scripts directly into memory.
Persistence:
- Registry Run key entries.
- WMI event subscription for re-launch on reboot.
DLL Side-Loading: Drops malicious DLLs in directories of signed binaries.

Section 3: Command & Control (C2)

Encrypted Communication: TLS 1.3 with custom obfuscation.
Beaconing Pattern: Sends 1KB dummy packets every 90s to avoid detection.
C2 Domains: Rotating domain generation algorithm (DGA).

Section 4: Capabilities

Data Exfiltration: Uploads sensitive files to attacker C2.
Credential Dumping: Uses lsass memory scraping + Mimikatz module.
Lateral Movement: Exploits SMB & RDP for spreading.
Payload Delivery: Can deploy ransomware, cryptominers, or RATs.

Section 5: Indicators of Compromise (IOCs)

File Extensions: None (fileless execution).
Registry Keys:

HKCU\Software\Microsoft\Windows\CurrentVersion\Run\NotDoor
Domains:
update-service[.]xyz
checkin-node[.]net
Hashes:
SHA256: a7d2…ef9 (NotDoor DLL loader)
SHA256: b9f4…a32 (payload module)

Section 6: MITRE ATT&CK Mapping

T1059.003 – Command Execution (PowerShell)
T1071.001 – Web C2 Channel
T1547.001 – Registry Run Key Persistence
T1027 – Obfuscated Files & Information
T1562.001 – Disable Security Tools

Section 7: Detection & Mitigation

EDR/XDR: Watch for regsvr32 misuse and anomalous DLL loads.
SIEM Rules: Detect unusual beaconing traffic.
Threat Hunting: Look for registry keys linked to NotDoor persistence.
Network Segmentation: Contain lateral movement.
Patch Management: Close known exploited vulnerabilities.

Section 8: CyberDudeBivash NotDoor Defense Framework (CDB-NDF)

Prevent: Harden endpoints, enforce MFA, restrict PowerShell.
Detect: Monitor registry anomalies, DGA domain traffic.
Respond: SOAR playbooks to isolate compromised hosts.
Recover: Ensure clean backups of system images.
Hunt: Continuous red-team exercises simulating NotDoor.

Section 9: Future Outlook

Likely to evolve into Ransomware Loader-as-a-Service.
Increasing adoption of AI-driven evasion tactics.
Cross-platform expansion to Linux & macOS backdoors.

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Conclusion

NotDoor malware demonstrates the next-gen sophistication of backdoors: stealth, modularity, and adaptability. Enterprises must adopt CyberDudeBivash’s layered defense frameworks to minimize exposure and disruption.

At CyberDudeBivash, we deliver advanced malware analysis, threat intelligence, and mitigation playbooks to outpace adversaries.

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