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🎯 Midnight Blizzard's RDP Spear-Phishing Campaign: A Deep Dive

🎯 Midnight Blizzard's RDP Spear-Phishing Campaign: A Deep Dive

 CyberHawk Consultancy

💥 Summary of the Threat

In October 2024, Microsoft Threat Intelligence uncovered a sophisticated and large-scale spear-phishing campaign by the Russian state-sponsored group Midnight Blizzard (also known as APT29/NOBELIUM).

Their unique weapon of choice? Malicious RDP files — cleverly engineered to establish live remote sessions with attacker-controlled infrastructure.

🛠️ How the Attack Works

Unlike traditional payloads, these attacks used signed RDP configuration files attached to phishing emails. When a user clicked the RDP file:

  • 🔗 It initiated a remote session directly with Midnight Blizzard-controlled infrastructure.
  • 🔍 Exploited legitimate RDP capabilities to:
    • 📁 Access local files and directories
    • 🖨️ Enumerate peripherals (smartcards, printers, webcams)
    • 📋 Capture clipboard contents
    • 🔐 Steal authentication tokens (Windows Hello, Passkeys)
    • 🛒 Interact with Point of Sale (POS) devices

👉 These .rdp files were signed using valid certificates to evade detection, and disguised as coming from Microsoft or cloud providers.

🌍 Targeted Sectors & Geography

  • 🏛️ Government Agencies
  • 🏫 Academic Institutions
  • 🛡️ Defense Contractors
  • 🌐 NGOs and Think Tanks

📌 Geographically, the campaign focused on:

  • 🇬🇧 United Kingdom
  • 🇯🇵 Japan
  • 🇪🇺 Europe
  • 🇦🇺 Australia

🔍 Detection Strategies

  • 🛡️ Microsoft Defender for Office 365: Scans attachments for known malicious .rdp patterns.
  • ⚙️ RDP File Parser Tool: Identifies suspicious config parameters in RDP files.
  • 📁 Defender Alerts: Look for alert titles like Trojan_RDP*.
  • 📌 Hunting Queries: Custom queries to detect RDP connections initiated via email attachments.

🕵️‍♂️ Microsoft Sentinel Detections (KQL)

Below are ready-to-use Microsoft Sentinel KQL queries to help hunt and detect Midnight Blizzard's RDP spear-phishing campaign. Use these in Sentinel’s Logs section or integrate into your analytic rules.

1️⃣ RDP File Opened from Email Attachment


EmailEvents
| where Attachments has ".rdp"
| project TimeGenerated, SenderFromAddress, Subject, Attachments, NetworkMessageId

2️⃣ Suspicious RDP Client Connection


DeviceNetworkEvents
| where RemotePort == 3389
| where RemoteIPCountry in ("Russia", "Unknown")
| project TimeGenerated, DeviceName, InitiatingProcessFileName, RemoteIP, RemotePort

3️⃣ Unusual RDP Parameters in .rdp Files


DeviceFileEvents
| where FileName endswith ".rdp"
| where FileContent contains "full address:s:" or FileContent contains "loadbalanceinfo:s:"
| project TimeGenerated, FileName, FolderPath, InitiatingProcessAccountName

4️⃣ Suspicious Process Activity Related to RDP Launch


DeviceProcessEvents
| where FileName in ("mstsc.exe", "RDCMan.exe")
| where InitiatingProcessFileName endswith ".rdp"
| project TimeGenerated, FileName, InitiatingProcessFileName, InitiatingProcessCommandLine

5️⃣ Credential Theft Indicators


DeviceLogonEvents
| where LogonType == 10 and AccountType == "User"
| where RemoteDeviceName has_any ("mfa", "auth", "secure", "vpn")
| project TimeGenerated, AccountName, RemoteDeviceName, LogonType

6️⃣ Detected Known Threat Pattern (Microsoft Defender)


SecurityAlert
| where AlertName startswith "Trojan_RDP"
| project TimeGenerated, AlertName, Description, Computer, ExtendedProperties

7️⃣ External RDP Connections from Non-Jump Servers


Heartbeat
| where RemoteIP != "" and RemotePort == 3389
| where DeviceType != "JumpHost"
| summarize count() by Computer, RemoteIP

💡 Bonus Tip: Use Watchlists

🎯 Add known malicious IPs and RDP hash IOCs to a Sentinel watchlist and reference it in analytic rules or workbook queries for proactive defense.

🧰 Mitigation Recommendations

🖥️ Endpoint Protection

  • 🔒 Enable Tamper Protection & Network Protection in Defender
  • 🚫 Activate EDR in Block Mode to stop post-execution threats
  • 🧠 Use Automated Investigation & Remediation

📧 Email Security

  • 🧼 Enable Safe Links and Safe Attachments in Microsoft 365
  • ♻️ Use Zero-Hour Auto Purge (ZAP) to retroactively clean threats

🌐 Web Browsing Security

  • 🧭 Use browsers with SmartScreen (e.g., Microsoft Edge)

🧠 User Awareness

  • ❗ Train staff not to open unknown RDP files
  • ✔️ Verify legitimacy of senders, especially those claiming to be from Microsoft or cloud providers

🚨 IOC-Based Detection (Example)


File Extension: .rdp
Remote Addresses: *.onmicrosoft.com (used by APT29 for infrastructure)
Common File Names:
  - SecureAccess.rdp
  - InviteToCall.rdp
  - MFA_Connection.rdp

Suspicious RDP Parameters:
  - full address:s:
  - loadbalanceinfo:s:
  - username:s:admin

🔚 Final Thoughts

This campaign marks an evolution in spear-phishing tradecraft — combining legitimate remote desktop tools with advanced social engineering and credential theft.

By proactively hunting and defending against these novel attack vectors, organizations can stay ahead of nation-state adversaries like Midnight Blizzard.

💡 Pro Tip: Disable automatic opening of RDP files via Group Policy in enterprise environments to reduce risk exposure.

📚 Sources & References

🦅 CyberHawk Consultancy | They can't exploit you if you are the exploit.

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