Last Updated on October 31, 2025 by Arnav Sharma
Azure Blob Storage has become a prime target for attackers in 2025, and the situation deserves your attention. We’re witnessing sophisticated, well-orchestrated campaigns that exploit everything from basic misconfigurations to complex cloud-native integrations. The troubling part? Many organizations don’t realize they’ve been compromised until significant damage has occurred.
I’ve been tracking these incidents closely, and what Microsoft Threat Intelligence reports aligns with what security teams are experiencing in the field. We’re seeing full intrusion chains, unauthorized data exfiltration, ransomware deployments, and even supply chain compromises. The threat landscape has shifted considerably.
Let me walk you through what’s actually happening, why these attacks are escalating so rapidly, and most importantly, what you can do to protect your environment.
Why Attackers Target Azure Blob Storage
Understanding the appeal requires looking at what Blob Storage actually handles. It’s Microsoft’s scalable object storage service for unstructured data, managing exabytes of information across diverse workloads: AI/ML datasets, high-performance computing, analytics pipelines, media streaming, enterprise backups, disaster recovery systems, and IoT data ingestion.
The architecture is straightforward. Storage accounts contain unlimited containers and blobs (essentially files), with features like versioning, immutability policies, soft delete, and deep integration with services such as Azure Functions, Logic Apps, Data Factory, and Synapse Analytics.
So what makes this such an attractive target?
Data Sensitivity and Scale
A single compromised storage account can expose ML training data (vulnerable to poisoning attacks), complete backup sets, or critical intellectual property. The potential impact extends across entire organizations, making it a high-value target for both financially motivated groups and espionage-focused threat actors.
Extensive Cloud Integration
Blobs can trigger automated workflows through Event Grid. An attacker uploads a crafted file, and suddenly it’s executing code in Azure Functions with elevated privileges. These integration points create opportunities for lateral movement that weren’t possible with traditional storage systems.
Common Misconfigurations
Public containers remain surprisingly prevalent. Over-permissive Shared Access Signature (SAS) tokens get scattered across codebases. Storage keys end up exposed in GitHub repositories. These configuration errors provide low-barrier entry points that require minimal technical sophistication to exploit.
The Monitoring Gap
Most security teams focus heavily on compute resources like virtual machines and Kubernetes clusters. Blob Storage, however, often receives less attention. As a “data layer” service rather than compute-focused infrastructure, it frequently lacks robust monitoring. This creates a blind spot that attackers actively exploit.
Threat actors have figured this out. They’re repurposing Blob Storage for malware hosting, command-and-control infrastructure, and data exfiltration staging. What Microsoft designed as a storage service has become an attack platform in the wrong hands.
The Complete Attack Chain
These attacks follow structured patterns, often mapped to the MITRE ATT&CK framework for Enterprise (Cloud). Threat actors exploit cloud-native features to move from initial reconnaissance through final impact. Here’s how the full chain typically unfolds:
Stage 1: Reconnaissance
Attackers start by identifying exposed resources and credentials. They probe DNS and HTTP endpoints for *.blob.core.windows.net subdomains, using AI-generated wordlists to brute-force account and container names. Tools like Goblob, QuickAZ, or custom PowerShell scanners automate this process.
They also harvest storage keys and SAS tokens from code repositories (GitHub is a goldmine) and configuration files. Passive DNS databases help them map out your Azure footprint without triggering obvious alarms.
Stage 2: Resource Development
Once they’ve identified potential targets, attackers create malicious infrastructure using Blob Storage itself. They host spoofed Microsoft sign-in pages that evade SSL certificate checks. They inject malicious executables, macro-laden documents, or poisoned ML datasets into public containers. Blobs become staging grounds for payloads that will be used later in the attack.
Stage 3: Initial Access
The entry point varies, but common methods include:
- Abusing blob-triggered automationsย through Azure Functions via Event Grid or Logic Apps
- Phishing campaignsย using Azure-hosted malicious PDFs that trick users into granting Microsoft 365 access
- Direct accessย using leaked SAS tokens or storage keys
What makes these effective is that they blend with legitimate Azure traffic. Your security tools see valid Azure API calls, not obvious intrusion attempts.
Stage 4: Persistence
Smart attackers don’t just break in once. They establish multiple footholds:
- Assigning elevated RBAC (Role-Based Access Control) or ABAC (Attribute-Based Access Control) roles to identities they control
- Generating broad, long-expiry SAS tokens for ongoing access
- Enabling SFTP access to storage accounts
- Using soft-delete features to hide and later restore malicious payloads
Tools like AADInternals facilitate backdoor creation, while AzureHound automates privilege escalation reconnaissance.
Stage 5: Defense Evasion
To avoid detection, attackers modify security configurations:
- Loosening firewall rules
- Adding permissive IP or VNet allowlists
- Disabling diagnostic logging (if they have sufficient privileges)
- Distributing requests across multiple Azure regions to avoid rate-limiting
- Tampering with or deleting audit logs
These actions help them operate undetected for extended periods.
Stage 6: Credential Access
With initial access secured, attackers hunt for additional credentials:
- Reusing Entra ID (formerly Azure AD) refresh tokens
- Invoking APIs likeย
listKeysย to retrieve storage account keys - Dumping Cloud Shell caches from hidden blob containers
- Intercepting unencrypted traffic where possible
Each credential discovered expands their access and makes remediation more complex.
Stage 7: Discovery
Attackers systematically map your environment, enumerating:
- Subscriptions and resource groups
- Storage accounts, containers, and blobs
- Configuration details (firewall rules, immutability policies)
- Sensitive data locations
This reconnaissance informs their next moves and helps them identify the highest-value targets.
Stage 8: Lateral Movement
Cloud integration becomes a weapon. Attackers upload crafted files that trigger Azure Functions or Logic Apps with managed identities. They replace legitimate Function code stored in blobs. They manipulate data pipelines in services like Data Factory, potentially compromising downstream systems.
Stage 9: Collection
Data gathering happens methodically:
- Listing and downloading blobs using AzCopy, SyncCopy, or REST APIs
- Copying data to attacker-controlled containers
- Compressing and encrypting data within your environment (to avoid detection during transfer)
Stage 10: Command and Control
Some sophisticated attacks use blob metadata for covert command-and-control channels. Malware beacons by polling metadata via HEAD or GET requests without downloading full blobs. Commands get embedded in metadata fields. Objects get replicated across regions for payload distribution.
This technique is particularly clever because it generates minimal network traffic and looks like routine storage management.
Stage 11: Exfiltration
When they’re ready to move data out:
- High-bandwidth transfers using AzCopy or Azure Storage Explorer
- Enabling static website hosting in theย
$webย container for data staging - Automating exfiltration through Azure Functions or runbooks
- Chunking data to stay under detection thresholds
- Exploiting integrations with third-party tools like MOVEit Transfer
Stage 12: Impact
The final stage varies by attacker motivation:
- Mass deletions or overwritesย to cause operational disruption
- Ransomware encryptionย of blobs with demands for payment
- Metadata modificationย to corrupt data integrity
- Data poisoningย in ML datasets to sabotage AI workflows
The damage can range from temporary business disruption to permanent data loss or compromised AI models.
Why 2025 Has Been Particularly Bad
Several factors have converged to make this year especially challenging:
The Cloud-Native Threat Shift
As traditional endpoints become harder to compromise (thanks to EDR and other defenses), attackers have pivoted to cloud infrastructure. Storage services are particularly attractive because logging is often paywalled, incomplete, or simply disabled to save costs.
AI and Automation Advantages
Threat actors now use large language models for efficient brute-forcing and reconnaissance. Tools like AzureHound automate privilege escalation discovery. The scale and speed of attacks have increased dramatically.
The Misconfiguration Epidemic
Many organizations over-rely on default configurations without understanding the security implications. Integrations with third-party tools introduce additional vulnerabilities. The complexity of cloud security often exceeds the expertise available to manage it.
Strong Economic Incentives
High-value data enables lucrative ransomware operations. Espionage campaigns find treasure troves of intellectual property. Detection risks remain low in under-monitored environments. The risk-reward calculation strongly favors attackers.
Broader Security Evolution
Microsoft’s Secure Future Initiative highlights how threats have evolved beyond compute security to target the data layer directly. Storage services represent the new frontier in cloud security.
Real-World Examples
Let me share some concrete cases that illustrate these threats:
Phishing via Blob-Hosted PDFs
Attackers host malicious PDF files on Azure Blob URLs (like storage.blob.core.windows.net). Users receive convincing phishing emails with these links. When clicked, victims see what appears to be a legitimate Microsoft login page, but granting access provides attackers with tenant-level permissions.
The mitigation? Blockย *.blob.core.windows.netย except for explicitly trusted storage accounts.
MOVEit Transfer Exploitation
The Lace Tempest group (associated with Clop ransomware) exploited vulnerabilities in MOVEit Transfer software that integrated with Blob Storage. This enabled large-scale exfiltration from backup and archiving systems. While the initial vulnerability was discovered in 2023, similar integration weaknesses continue to emerge.
Storm-0501 Ransomware Campaign
This threat group abused Azure Storage encryption scopes to encrypt blobs directly within storage accounts. It represents the evolution of ransomware from traditional file encryption to cloud-native approaches that are harder to detect and remediate.
ML Data Poisoning
Attackers inject mislabeled or corrupted samples into training datasets stored in Blob Storage. When organizations train AI models on this poisoned data, the resulting models produce unreliable or manipulated outputs. This technique is particularly insidious because the impact may not be immediately obvious.
Covert C2 via Metadata
Security researchers have observed malware that beacons by polling blob metadata without downloading full files. This generates minimal network traffic and appears as routine storage management activity, making it extremely difficult to detect through traditional monitoring.
How to Defend Your Environment
Protecting Azure Blob Storage requires adopting Zero Trust principles and implementing layered defenses. Here’s what actually works:
Identity and Access Management
Start with Microsoft Entra ID (formerly Azure AD) and implement strict RBAC or ABAC for least-privilege access. Disable anonymous access and shared key authorization wherever possible. Rotate storage keys and SAS tokens regularly, and use short expiration periods for SAS tokens.
Consider this the foundation. If you get access controls wrong, everything else becomes significantly harder.
Network Security
Mandate HTTPS for all storage operations. Use private endpoints to keep traffic off the public internet. Implement VNet rules and storage firewalls to restrict access to known, trusted networks only.
Public access should be the rare exception, not the default.
Data Protection
Enable Server-Side Encryption (SSE) with AES-256 for all data at rest. Consider double encryption for highly sensitive workloads. Implement immutability policies, soft delete, and versioning to protect against ransomware and accidental deletion.
These features give you recovery options when (not if) something goes wrong.
Monitoring and Detection
This is where many organizations fall short. Activate Microsoft Defender for Storage, which provides malware scanning and anomaly detection like “Unusual unauthenticated access” alerts. Enable Defender CSPM (Cloud Security Posture Management) for attack path analysis and sensitive data discovery.
Integrate with Microsoft Purview for comprehensive data governance and classification. You can’t protect what you can’t see.
AI-Specific Protections
If you’re storing ML datasets, implement scanning for data poisoning attempts. Validate data integrity before training runs. Monitor for unauthorized modifications to training data.
General Best Practices
Follow Azure security baselines published by Microsoft. Use Security Copilot for incident response when attacks occur. Audit code repositories for leaked credentials. Enable comprehensive logging and automate response workflows via Event Grid.
Treat security as an ongoing process, not a one-time configuration exercise.
Moving Forward
The threat landscape around Azure Blob Storage isn’t going away. If anything, attacks will become more sophisticated as defenders improve their posture. Staying informed matters.
Monitor Microsoft’s Security Blog for emerging threats. Pay attention to Defender alerts. If you’re managing Azure infrastructure, prioritizing Defender for Storage activation should be near the top of your list. Early detection makes the difference between a minor incident and a major breach.
The attackers have industrialized their approach to cloud storage. Your defenses need to match that level of sophistication. Start with the basics (access controls, network security, encryption), layer on robust monitoring, and maintain the discipline to respond quickly when alerts fire.
Your data deserves better than being low-hanging fruit.