Techniques
Sample rules
AWS IAM AccessDenied Discovery Events
- source: splunk
- technicques:
- T1580
Description
The following analytic identifies excessive AccessDenied events within an hour timeframe for IAM users in AWS. It leverages AWS CloudTrail logs to detect multiple failed access attempts from the same source IP and user identity. This activity is significant as it may indicate that an access key has been compromised and is being misused for unauthorized discovery actions. If confirmed malicious, this could allow attackers to gather information about the AWS environment, potentially leading to further exploitation or privilege escalation.
Detection logic
`cloudtrail` (errorCode = "AccessDenied") user_type=IAMUser (userAgent!=*.amazonaws.com)
| bucket _time span=1h
| rename user_name as user
| stats count as failures min(_time) as firstTime max(_time) as lastTime, dc(signature) as methods, dc(dest) as sources values(signature) as signature values(dest) as dest by src, user, vendor_account vendor_region, vendor_product
| where failures >= 5 and methods >= 1 and sources >= 1
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `aws_iam_accessdenied_discovery_events_filter`
ASL AWS IAM AccessDenied Discovery Events
- source: splunk
- technicques:
- T1580
Description
The following analytic identifies excessive AccessDenied events within an hour timeframe for IAM users in AWS. It leverages AWS CloudTrail logs to detect multiple failed access attempts from the same source IP and user identity. This activity is significant as it may indicate that an access key has been compromised and is being misused for unauthorized discovery actions. If confirmed malicious, this could allow attackers to gather information about the AWS environment, potentially leading to further exploitation or privilege escalation.
Detection logic
`amazon_security_lake` api.response.error=AccessDenied OR api.response.error=OperationNotPermittedException OR api.response.error=*Unauthorized* actor.user.type=IAMUser
| bucket _time span=1h
| stats count as failures min(_time) as firstTime max(_time) as lastTime dc(api.operation) as dc_operation, dc(api.service.name) as dc_service values(api.operation) as api.operation values(api.service.name) as api.service.name values(http_request.user_agent) as http_request.user_agent values(src_endpoint.ip) as src_ip values(actor.user.account.uid) as actor.user.account.uid values(cloud.provider) as cloud.provider values(cloud.region) as cloud.region by _time actor.user.uid
| where failures >= 5 AND dc_operation >= 1 AND dc_service >= 1
| rename actor.user.uid as user api.operation as action api.service.name as dest http_request.user_agent as user_agent src_endpoint.ip as src actor.user.account.uid as vendor_account cloud.provider as vendor_product cloud.region as vendor_region
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `asl_aws_iam_accessdenied_discovery_events_filter`