Detect Direct Cloud VM Connections in Elastic Security
Adversaries may leverage Valid Accounts to log directly into cloud-hosted virtual infrastructure using cloud-native connection methods. Cloud providers offer interactive console access to VMs that bypasses traditional network controls: Azure Serial Console, AWS EC2 Instance Connect, AWS Systems Manager Session Manager (SSM), and GCP OS Login. These methods authenticate via the cloud IAM layer rather than network credentials, can bypass firewall rules and security groups, and often provide SYSTEM or root-level access by default. Adversaries who compromise cloud IAM credentials can pivot to VM instances using these native APIs, even when SSH/RDP is blocked at the network level.
MITRE ATT&CK
- Tactic
- Lateral Movement
- Technique
- T1021 Remote Services
- Sub-technique
- T1021.008 Direct Cloud VM Connections
- Canonical reference
- https://attack.mitre.org/techniques/T1021/008/
Elastic Detection Query
any where (
(
event.dataset == "aws.cloudtrail"
and event.provider in ("ssm.amazonaws.com", "ec2-instance-connect.amazonaws.com")
and event.action in (
"StartSession", "ResumeSession", "TerminateSession",
"SendCommand", "StartAutomationExecution",
"SendSSHPublicKey", "StartSSHSession"
)
)
or
(
event.dataset == "azure.activitylogs"
and azure.activitylogs.operation_name in~ (
"MICROSOFT.COMPUTE/VIRTUALMACHINES/RUNCOMMAND/ACTION",
"MICROSOFT.SERIALCONSOLE/CONSOLESERVICES/ACCESS",
"MICROSOFT.COMPUTE/VIRTUALMACHINES/EXTENSIONS/WRITE"
)
)
)Detects direct cloud VM connections via cloud-native methods including AWS SSM Session Manager, EC2 Instance Connect, and Azure Serial Console / Run Command. Queries the Elastic AWS CloudTrail integration index (logs-aws.cloudtrail-*) and Azure Activity Logs integration index (logs-azure.activitylogs-*). Relevant ECS fields: event.dataset, event.provider, event.action for AWS; azure.activitylogs.operation_name for Azure. Caller identity available via aws.cloudtrail.user_identity.arn and azure.activitylogs.identity.claims_initiated_by.name. Target instance via aws.cloudtrail.flattened.request_parameters.target.
Data Sources
Required Tables
False Positives & Tuning
- Legitimate SRE or DevOps engineers using AWS SSM Session Manager as a bastion-free SSH replacement for routine maintenance, patching, or troubleshooting.
- CI/CD pipelines or configuration management tooling (e.g., Ansible via SSM, AWS Systems Manager Automation runbooks) invoking SendCommand or StartAutomationExecution as part of deployment workflows.
- Azure VM extensions written by infrastructure automation (e.g., Azure Desired State Configuration, monitoring agent installation via ARM templates) triggering EXTENSIONS/WRITE during scheduled deployments.
- Cloud security or compliance tools using Azure Run Command or AWS SSM to collect inventory data or run health checks as part of scheduled scanning.
Other platforms for T1021.008
Testing Methodology
Validate this detection against 4 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1AWS SSM Send Command to EC2 Instance
Expected signal: AWS CloudTrail event: eventName=SendCommand, eventSource=ssm.amazonaws.com, with instanceId, documentName, and parameters. CloudWatch Log stream for the command output (if session logging enabled). Source IP address recorded in CloudTrail.
- Test 2AWS EC2 Instance Connect (Temporary SSH Key Injection)
Expected signal: AWS CloudTrail: SendSSHPublicKey event from ec2-instance-connect.amazonaws.com with instanceId, osUser, and publicKey fingerprint. Subsequent SSH connection attempt to the instance.
- Test 3Azure Run Command on VM
Expected signal: Azure Activity Log: MICROSOFT.COMPUTE/VIRTUALMACHINES/RUNCOMMAND/ACTION operation by the executing identity. The script content is visible in the Properties field. Source IP recorded in httpRequest.clientIpAddress.
- Test 4Start AWS SSM Session Manager Interactive Session
Expected signal: AWS CloudTrail: StartSession event from ssm.amazonaws.com with target instanceId, sessionId, and caller identity. Session logs in CloudWatch if session logging enabled. Note: interactive session content is only captured if session logging is configured.
References (7)
- https://attack.mitre.org/techniques/T1021/008/
- https://learn.microsoft.com/en-us/troubleshoot/azure/virtual-machines/serial-console-overview
- https://docs.aws.amazon.com/systems-manager/latest/userguide/session-manager.html
- https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/Connect-using-EC2-Instance-Connect.html
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1021.008/T1021.008.md
- https://www.mandiant.com/resources/blog/sim-swapping-and-abuse-of-the-microsoft-azure-serial-console
- https://www.cisa.gov/news-events/cybersecurity-advisories/aa23-320a
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