AWS EC2 Role GetCallerIdentity from New Source AS Organization
Identifies the first time an EC2 instance role session calls AWS STS GetCallerIdentity from a given source autonomous system (AS) organization name within the lookback window. Adversaries who steal instance role…
Description
Identifies the first time an EC2 instance role session calls AWS STS GetCallerIdentity from a given source autonomous system (AS) organization name within the lookback window. Adversaries who steal instance role credentials often verify them with GetCallerIdentity from infrastructure outside your normal egress paths. Baseline learning on the pairing of identity and source network reduces noise from stable NAT or AWS-classified egress compared to alerting on every call from a non-Amazon ASN.
Detection logic
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Detection requirements
- Platform
- ESXiIaaSIdentity ProviderLinuxmacOSOffice SuiteSaaSWindows
The rule states no platform. This is derived from the ATT&CK technique it maps to.
- Log source category
- event_index
Known benign triggers
- New EC2 workloads, NAT or egress changes, ISP renumbering, or GeoIP database updates can change `source.as.organization.name` for the same logical path. Roles that legitimately call STS from many networks (for example, developer-exported temporary credentials) may also produce alerts. Tune using role ARN, account, or user agent where appropriate.
MITRE ATT&CK mappings
0 exclusive techniques.This is coverage no other published rule has; it is not this rule's total technique count.
References
| Reference | Cited by |
|---|---|
| detectioninthe.cloud/ttps/discovery/sts_get_caller_identity | 2 |
| docs.aws.amazon.com/STS/latest/APIReference/API_GetCallerIdentity.html | 3from 2 sources |
From the source
- At source
- Open at source
- Upstream identifier
- b2f8c4e1-6a73-4f1e-9c2d-8e5b0a1d3f7c
- Tagged by the source as
- Data Source: Amazon Web ServicesData Source: AWSData Source: AWS CloudTrailData Source: AWS STSDomain: CloudDomain: IdentityNoise: UnknownPerformance: NormalPlatform: AWSResources: Investigation GuideRule Type: New TermsService: AWS EC2Service: AWS STSTactic: DiscoveryUse Case: Identity and Access AuditUse Case: Threat Detection
Licence
- Published under
- Elastic License 2.0Read the licence
- Attribution
- Required
Authorship
- Written by
- Published
- Sep 20, 2026
- Version
- 3