Techniques
Sample rules
AWS Cross Account Activity From Previously Unseen Account
- source: splunk
- technicques:
Description
The following analytic identifies AssumeRole events where an IAM role in a different AWS account is accessed for the first time. It detects this activity by analyzing authentication logs and comparing the requesting and requested account IDs, flagging new cross-account activities. This behavior is significant because unauthorized cross-account access can indicate potential lateral movement or privilege escalation attempts. If confirmed malicious, an attacker could gain unauthorized access to resources in another account, potentially leading to data exfiltration, service disruption, or further compromise of the AWS environment.
Detection logic
| tstats min(_time) as firstTime max(_time) as lastTime from datamodel=Authentication where Authentication.signature=AssumeRole by Authentication.vendor_account Authentication.user Authentication.src Authentication.user_role
| `drop_dm_object_name(Authentication)`
| rex field=user_role "arn:aws:sts:*:(?<dest_account>.*):"
| where vendor_account != dest_account
| rename vendor_account as requestingAccountId dest_account as requestedAccountId
| lookup previously_seen_aws_cross_account_activity requestingAccountId, requestedAccountId, OUTPUTNEW firstTime
| eval status = if(firstTime > relative_time(now(), "-24h@h"),"New Cross Account Activity","Previously Seen")
| where status = "New Cross Account Activity"
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `aws_cross_account_activity_from_previously_unseen_account_filter`