The following analytic identifies an authentication attempt event against an AWS Console that fails during the Multi Factor Authentication challenge. AWS Cloudtrail logs provide a a very useful field called
additionalEventData that logs information regarding usage of MFA. This behavior may represent an adversary trying to authenticate with compromised credentials for an account that has multi-factor authentication enabled.
- Type: TTP
Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Last Updated: 2022-10-03
- Author: Bhavin Patel, Splunk
- ID: 55349868-5583-466f-98ab-d3beb321961e
Kill Chain Phase
- CIS 10
1 2 3 4 5 `cloudtrail` eventName= ConsoleLogin errorMessage="Failed authentication" additionalEventData.MFAUsed = "Yes" | stats count min(_time) as firstTime max(_time) as lastTime by src eventName eventSource aws_account_id errorCode errorMessage userAgent eventID awsRegion user_name userIdentity.arn | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `aws_console_login_failed_during_mfa_challenge_filter`
The SPL above uses the following Macros:
aws_console_login_failed_during_mfa_challenge_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
List of fields required to use this analytic.
How To Implement
The Splunk AWS Add-on is required to utilize this data. The search requires AWS Cloudtrail logs.
Known False Positives
Legitimate users may miss to reply the MFA challenge within the time window or deny it by mistake.
Associated Analytic Story
|64.0||80||80||User $user_name$ failed to pass MFA challenge while logging into console from $src$|
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
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