Technical Overview of an Azure Security Incident

Technical Overview of an Azure Security Incident

Nov 10, 2023·

8 min read

In this detailed account, we dissect a security incident within an Azure-managed environment, characterized by an advanced persistent threat that managed to exploit a subtle Server-Side Request Forgery (SSRF) vulnerability within a third-party .NET library. This library was utilized by an application running in a containerized environment managed by the Azure Kubernetes Service (AKS). The technical complexities of this scenario stem from the intricate interactions between Azure services and the sophisticated nature of the exploit.

Initial Threat Detection

Identifying the Anomaly

The initial anomaly was surfaced through Azure Monitor’s integrated telemetry. Azure Monitor, in tandem with Azure Log Analytics, had been configured with a set of complex alerting rules. These rules were designed to flag deviations from established network traffic patterns, particularly focusing on egress data streams.

Telemetry Configuration

The telemetry pipeline was custom-configured to collect metrics on a granular scale from AKS-managed containers. This configuration included:

  • Network Metric Collection: Detailed collection of network metrics like traffic volume, packet sizes, and connection states from the AKS nodes.

  • Application Insights Integration: Application performance metrics, including response times, failure rates, and dependency rates, were harnessed from within the application workloads.

  • Custom Kusto Query Language (KQL) Alerts: Alerts were crafted using KQL to analyze patterns across collected metrics, with thresholds set to detect abnormal surges in outbound traffic volume, new or unusual endpoint connections, and irregular data transfer rates.

Anomaly Detection

The anomaly detection mechanism employed by Azure Monitor leveraged machine learning to establish a baseline of normal activity over an extended period. When the outbound traffic to an unrecognized endpoint significantly exceeded the established baseline, the alert was triggered.

Initial Alert

The alert detailed a sustained increase in outbound HTTPS requests from a particular pod within the AKS cluster. This pod was part of a microservice architecture handling payment processing data, a critical component of the application with stringent security requirements.

Advanced Diagnostics

To further diagnose the anomaly, we utilized Azure Network Watcher’s packet capture feature to record a segment of the outgoing traffic from the implicated pod. This capture provided the raw data needed to perform a detailed analysis of the traffic, revealing that the requests to the external endpoint contained encoded payload data typical of SSRF attacks.

With the anomaly identified and the suspicion of an SSRF attack, we leveraged Azure’s native capabilities to trace the source of the traffic and to define the scope of the potential breach. The specifics of this telemetry and anomaly detection configuration provided the first crucial steps in addressing the security threat posed by the SSRF vulnerability.

The subsequent sections will delve into the intricate processes of version control, system rollback, and long-term resolution strategies that form the crux of our comprehensive response to this complex security challenge within the Azure environment.

Deployment Strategy and Version Control

In our Azure environment, every deployment to the Azure Kubernetes Service (AKS) is managed through Azure DevOps pipelines which are configured to perform the following actions:

  • Version Tagging: Each build and deployment is tagged with a unique version number, which includes the timestamp and a hash of the build artifacts. This versioning scheme allows us to quickly identify and correlate deployed code with specific commits in our source control system.

  • Immutable Artifacts: All build artifacts are immutable once created. They are stored in a secure Azure Container Registry with retention policies to maintain a history of all images.

  • Change Tracking: Azure DevOps is configured to track all changes that occur within the environment. Each deployment record includes detailed information about the changes made, including which containers were updated and what configurations were altered.

Identifying the Last Known Good State

  • Deployment Snapshots: Before any new deployment, a snapshot of the current state, including configurations and running container images, is automatically created and stored securely in Azure Blob Storage. These snapshots represent a point-in-time state of the system.

  • Telemetry and Anomaly Detection: Azure Monitor and Azure Log Analytics collect and analyze telemetry data from AKS. Anomaly detection policies are in place to alert on unusual patterns that may indicate a security issue, such as unexpected outbound traffic.

  • Incident Correlation: When an anomaly is detected, the time of the anomaly is correlated with the deployment history. By examining the deployments that occurred before the anomaly detection, and comparing the versions and configurations, we can determine the last deployment that did not exhibit the anomalous behavior.

  • Audit Logs and Alerts: The Azure Security Center and Azure Defender provide detailed audit logs and alerts. These tools were used to trace back to the exact time and nature of the vulnerability exploitation. By aligning this information with our deployment timeline, it was possible to pinpoint the deployment that introduced the vulnerability.

  • Rollback Procedures: With the precise time of the vulnerability introduction identified, we can revert the AKS environment to the last deployment snapshot taken before that time. This is possible due to the immutable nature of our deployment artifacts and the precise logging of changes in our CI/CD pipeline.

Resolution Strategy

Immediate Actions

1. Traffic Blocking: The immediate response to halting the data exfiltration involved Azure Network Security Groups (NSGs). The rationale here was to leverage NSGs’ capability to quickly enforce network-level security rules that could cut off the communication channel to the malicious external endpoint. An NSG rule was crafted to block outbound traffic to the IP address range identified, effectively stopping the data breach in its tracks.

2. Pod Isolation: The specific pod within the AKS cluster that was compromised needed to be isolated to prevent further exploitation. We scaled down the affected deployment to zero replicas using kubectl commands. This action removed the compromised pod from the network, thereby severing any ongoing attack vector through it.

Systematic Remediation

3. System Rollback: Identifying the last known good state allowed us to perform a targeted rollback. The rollback was not a blanket reversion but a strategic one, where only the affected services were rolled back to their previous state using the AKS kubectl rollout undo command, which is Azure’s native mechanism to revert to a prior deployment state in the event of a failure or breach.

4. Credential Rotation: Azure Key Vault was immediately used to rotate all the secrets and credentials that could have been potentially compromised. The automation of this process is vital, and the Key Vault access policies are configured to allow only specific Azure-managed identities to request secret rotations, providing an additional layer of security.

Long-term Fixes and Enhancements

5. Patch Application: The vulnerable third-party .NET library was identified, and a patched version was applied. Azure DevOps CI/CD pipelines were configured to include a new step that uses Azure Security Center’s vulnerability scanning tools to check for known vulnerabilities before any future deployments.

6. Infrastructure as Code (IaC) Revisions: Azure Resource Manager (ARM) templates and Terraform scripts were reviewed and updated to incorporate the new security rules and configurations as a permanent part of the infrastructure deployment process. This ensures that any new resources provisioned will automatically comply with the updated security posture.

7. Enhanced Monitoring and Alerting: Azure Monitor was fine-tuned to include more granular alerting policies based on the indicators of compromise observed during this incident. In addition, Azure Sentinel was set up to ingest logs from Azure Monitor and other sources, providing a centralized SIEM platform to correlate and analyze security data.

8. Automated Incident Response: Azure Logic Apps were deployed to automate the incident response for similar future incidents. These Logic Apps were programmed to trigger specific workflows such as isolating affected resources, rotating credentials, and notifying the security team when certain threat indicators are detected.

Post-Resolution Analysis and Adjustment

9. Security Posture Assessment: Following the resolution, Azure Secure Score in Azure Security Center was utilized to reassess the security posture of the environment. Recommendations provided by the Secure Score were implemented to enhance security further.

10. Compliance Alignment: Azure Policy was implemented to enforce specific compliance standards relevant to the organization’s industry, ensuring that all Azure resources remained compliant with regulatory requirements.

11. Drills and Simulations: To ensure the effectiveness of the new incident response automations and the updated security configurations, drills and simulations were scheduled. These exercises aim to stress-test the environment and the response protocols to ensure that the system would hold up under real attack scenarios.

Each step in the resolution strategy was taken with careful consideration of its immediate impact, the long-term security implications, and alignment with best practices. The overall goal was not only to resolve the present issue but also to enhance the security resilience of the Azure environment against future threats.

Post-Mortem and Best Practices

The resolution of the security incident led to a detailed post-mortem analysis, which is a critical process for improving security measures and preparing for potential future threats. This reflective exercise uncovered gaps in the security posture and informed the following best practices that were implemented.

Regular Dependency Audits

The incident underscored the necessity of regular audits of third-party dependencies. This practice is informed by the recognition that software supply chain attacks are on the rise and that staying updated with the latest patches is critical.

Security Blueprint Adoption

The adoption of Azure Blueprints for enforcing security standards was a strategic move to ensure consistent application of security controls across all cloud resources, an approach informed by the principles of policy-as-code.

Threat Intelligence Integration

Post-incident, it was clear that our threat detection needed to be more proactive. We resolved to integrate a real-time threat intelligence feed into Azure Sentinel. This decision was based on the understanding that threat intelligence provides context that can transform data points into actionable insights.

Continuous Improvement

Lastly, the incident reinforced the importance of continuous learning and improvement. Keeping abreast of the latest Azure updates, participating in security webinars and workshops, and conducting regular review sessions of the security infrastructure became integral parts of the team’s ongoing efforts to secure the environment.

In summary, the incident provided valuable lessons in the complex interplay of Azure services and security. By adopting a layered approach to defense, continuously improving our security practices, and utilizing Azure’s advanced security tools, we can fortify our cloud environment and maintain the trust of our users and stakeholders.