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Malware actors are now leveraging Azure Blob Storage metadata for Command and Control (C2) communications to evade detection. This technique allows attackers to hide malicious communications within legitimate cloud storage traffic, making it harder for traditional security tools to identify threats.
You Should Know:
Detection with KQL (Microsoft Defender for Endpoint)
Steven Lim has developed a KQL (Kusto Query Language) detection rule for identifying potential C2 communications via Azure Blob metadata. Below is the verified query:
// Malware C2 Comms over Azure Blob Metadata Detection let timeframe = 7d; DeviceNetworkEvents | where Timestamp > ago(timeframe) | where RemoteUrl has "blob.core.windows.net" | where AdditionalFields has "metadata" | where ActionType == "HttpRequest" | project Timestamp, DeviceName, RemoteUrl, InitiatingProcessFileName, AdditionalFields | sort by Timestamp desc
Steps to Mitigate & Investigate
1. Monitor Azure Blob Metadata Access
Check Azure Storage logs for unusual metadata changes az storage blob metadata show --container-name <container> --name <blob> --account-name <storage_account>
2. Enable Defender for Cloud Alerts
Enable Azure Defender for Storage az security pricing create -n 'StorageAccounts' --tier 'Standard'
3. Analyze Suspicious Traffic
Use tcpdump to capture Azure Blob traffic tcpdump -i eth0 'host blob.core.windows.net and port 443' -w azure_traffic.pcap
4. Check for Anomalies in Logs
Query Azure Activity Logs
Get-AzLog -StartTime (Get-Date).AddDays(-7) -EndTime (Get-Date) | Where-Object { $_.OperationName -like "metadata" }
Defensive Measures
- Restrict Metadata Permissions
Set Azure Blob metadata to read-only az storage container set-permission --name <container> --public-access off
- Implement Network Segmentation
Use Azure NSG to restrict outbound traffic az network nsg rule create --nsg-name <nsg-name> --name "Block-Suspicious-Blob" --priority 100 --direction Outbound --access Deny --destination-address-prefix ".blob.core.windows.net"
What Undercode Say
Attackers continuously evolve their techniques to bypass security controls. Monitoring metadata fields in cloud storage is now a critical detection surface. Organizations must enhance logging, implement strict access controls, and deploy behavioral-based detections to counter such threats.
Expected Output:
- Detection alerts for unusual Azure Blob metadata access.
- Network traffic logs showing C2 communications.
- Azure Defender for Storage triggering on anomalous behavior.
Prediction
As cloud adoption grows, attackers will increasingly abuse legitimate cloud services for stealthy C2 channels. Future malware may exploit other cloud metadata fields (e.g., AWS S3 tags, Google Cloud labels) for evasion. Proactive threat hunting and AI-driven anomaly detection will become essential.
Relevant URL:
References:
Reported By: 0x534c Cybersecurity – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
