A machine learning job detected an AWS API command that, while not inherently suspicious or abnormal, is being made by a user that does not normally use the command. This can be the result of compromised credentials or keys as someone uses a valid account to persist, move laterally, or exfiltrate data.
Rule type: machine_learning
Machine learning job: rare_method_for_a_username
Machine learning anomaly threshold: 75
Risk score: 21
Runs every: 15 minutes
Maximum alerts per execution: 100
Version: 3 (version history)
Added (Elastic Stack release): 7.9.0
Last modified (Elastic Stack release): 7.12.0
Rule authors: Elastic
Rule license: Elastic License v2
New or unusual user command activity can be due to manual troubleshooting or reconfiguration, changes in cloud automation scripts or workflows, adoption of new services, or changes in the way services are used.
Alerts from this rule indicate an AWS API command or method call that is rare and unusual for the calling IAM user. Here are some possible avenues of investigation:
Consider the user as identified by the
user.namefield. Is this command part of an expected workflow for the user context? Examine the user identity in the
aws.cloudtrail.user_identity.arnfield and the access key id in the
aws.cloudtrail.user_identity.access_key_idfield, which can help identify the precise user context. The user agent details in the
user_agent.originalfield may also indicate what type of client made the request.
- Consider the source IP address and geolocation for the calling user who issued the command. Do they look normal for the calling user? If the source is an EC2 IP address, is it associated with an EC2 instance in one of your accounts or could it be sourcing from an EC2 instance not under your control? If it is an authorized EC2 instance, is the activity associated with normal behavior for the instance role or roles? Are there any other alerts or signs of suspicious activity involving this instance?
- Consider the time of day. If the user is a human, not a program or script, did the activity take place during normal working hours?
Examine the history of the command. If the command, which is visible in the
event.action field, manifested only very recently, it might be part of a new automation module or script. If its usage rate is consistent - for example, if it appears in small numbers on a weekly or monthly basis - it might be part of a housekeeping or maintenance process.
- Examine the request parameters. These may provide indications as to the source of the program or the nature of the tasks it is performing.
- Version 3 (7.12.0 release)
- Formatting only
- Version 2 (7.10.0 release)
- Formatting only