This search looks for AWS CloudTrail events wherein a console login event by a user was recorded within the last hour, then compares the event to a lookup file of previously seen users (by ARN values) who have logged into the console. The alert is fired if the user has logged into the console for the first time within the last hour
- Type: Hunting
- Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Datamodel: Authentication
- Last Updated: 2022-05-10
- Author: Rico Valdez, Splunk
- ID: bc91a8cd-35e7-4bb2-6140-e756cc46fd71
Kill Chain Phase
- Actions on Objectives
- CIS 16
1 2 3 4 5 6 7 8 9 10 | tstats earliest(_time) as firstTime latest(_time) as lastTime from datamodel=Authentication where Authentication.signature=ConsoleLogin by Authentication.user | `drop_dm_object_name(Authentication)` | join user type=outer [ inputlookup previously_seen_users_console_logins | stats min(firstTime) as earliestseen by user] | eval userStatus=if(earliestseen >= relative_time(now(), "-24h@h") OR isnull(earliestseen), "First Time Logging into AWS Console", "Previously Seen User") | where userStatus="First Time Logging into AWS Console" | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `detect_aws_console_login_by_new_user_filter`
The SPL above uses the following Macros:
detect_aws_console_login_by_new_user_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
The SPL above uses the following Lookups:
How To Implement
You must install and configure the Splunk Add-on for AWS (version 5.1.0 or later) and Enterprise Security 6.2, which contains the required updates to the Authentication data model for cloud use cases. Run the
Previously Seen Users in CloudTrail - Initial support search only once to create a baseline of previously seen IAM users within the last 30 days. Run
Previously Seen Users in CloudTrail - Update hourly (or more frequently depending on how often you run the detection searches) to refresh the baselines.
Known False Positives
When a legitimate new user logins for the first time, this activity will be detected. Check how old the account is and verify that the user activity is legitimate.
Associated Analytic story
|30.0||50||60||User $user$ is logging into the AWS console for the first time|
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
source | version: 2