Cloud Infrastructure Discovery
Where this stands
No Sigma rule can address this — the telemetry MITRE names has no Sigma logsource behind it.
None of MITRE's analytics for this technique name a log source that maps to a Sigma logsource — they describe abstract data ("Process::None"), API-hook telemetry, or prose channels with no reliable field names behind them.
What the technique is
An adversary may attempt to discover infrastructure and resources that are available within an infrastructure-as-a-service (IaaS) environment. This includes compute service resources such as instances, virtual machines, and snapshots as well as resources of other services including the storage and database services. Cloud providers offer methods such as APIs and commands issued through CLIs to serve information about infrastructure. For example, AWS provides a DescribeInstances API within the Amazon EC2 API that can return information about one or more instances within an account, the ListBuckets API that returns a list of all buckets owned by the authenticated sender of the request, the HeadBucket API to determine a bucket’s existence along with access permissions of the request sender, or the GetPublicAccessBlock API to retrieve access block configuration for a bucket. Similarly, GCP's Cloud SDK CLI provides the gcloud compute instances list command to list all Google Compute Engine instances in a project, and Azure's CLI command az vm list lists details of virtual machines. In addition to API commands, adversaries can utilize open source tools to discover cloud storage infrastructure through Wordlist Scanning. An adversary may enumerate resources using a compromised user's access keys to determine which are available to that user. […]
Read it on attack.mitre.orgWhat MITRE says you would watch
- AN0481
Defenders should monitor for suspicious enumeration of cloud infrastructure components via APIs or CLI tools. Observable behaviors include repeated listing or description operations for compute instances, snapshots, storage buckets, and volumes. From a defender’s perspective, risky activity is often identified by new or untrusted identities making discovery calls (e.g., DescribeInstances, ListBuckets, az vm list, gcloud compute instances list), enumeration from unusual geolocations or IPs, or rapid multi-service discovery in sequence. Correlating discovery API usage with later snapshot creation or instance modification provides further context of adversary behavior.
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