AWS Multiple Failed MFA Requests For User

Status: production
Severity: low
Group by: _time, aws::awsRegion, aws::errorMessage, aws::recipientAccountId, signature, user, vendor_product
Author: Bhavin Patel
Source: github.com/splunk/security_content

The following analytic identifies multiple failed multi-factor authentication (MFA) requests to an AWS Console for a single user. It leverages AWS CloudTrail logs, specifically the additionalEventData field, to detect more than 10 failed MFA prompts within 5 minutes. This activity is significant as it may indicate an adversary attempting to bypass MFA by bombarding the user with repeated authentication requests. If confirmed malicious, this could lead to unauthorized access to the AWS environment, potentially compromising sensitive data and resources.

Known false positives

Multiple Failed MFA requests may also be a sign of authentication or application issues. Filter as needed.

MITRE ATT&CK coverage

Tactic	Techniques
Resource Development	`T1586.003` Compromise Accounts: Cloud Accounts
Credential Access	`T1621` Multi-Factor Authentication Request Generation

Telemetry coverage

Platform	Record / event type
AWS	CloudTrail event `ConsoleLogin`: Records an authentication attempt to the AWS Management Console, including whether it succeeded or failed.

Rules detecting the same action

These rules filter on the same operation.

AWS Console Login (Panther)
AWS Console Login Failed During MFA Challenge (Splunk)
AWS ConsoleLogin Failed Authentication (Sigma)
AWS CreateLoginProfile (Splunk)
AWS Credential Access Failed Login (Splunk)
AWS High Number Of Failed Authentications For User (Splunk)
AWS High Number Of Failed Authentications From Ip (Splunk)
AWS Multiple Users Failing To Authenticate From Ip (Splunk)

Rule body

name: AWS Multiple Failed MFA Requests For User
id: 1fece617-e614-4329-9e61-3ba228c0f353
version: 11
creation_date: '2022-10-03'
modification_date: '2026-05-13'
author: Bhavin Patel
status: production
type: Anomaly
description: The following analytic identifies multiple failed multi-factor authentication (MFA) requests to an AWS Console for a single user. It leverages AWS CloudTrail logs, specifically the `additionalEventData` field, to detect more than 10 failed MFA prompts within 5 minutes. This activity is significant as it may indicate an adversary attempting to bypass MFA by bombarding the user with repeated authentication requests. If confirmed malicious, this could lead to unauthorized access to the AWS environment, potentially compromising sensitive data and resources.
data_source:
    - AWS CloudTrail ConsoleLogin
search: |-
    `cloudtrail` eventName= ConsoleLogin "additionalEventData.MFAUsed"=Yes errorMessage="Failed authentication"
      | bucket span=5m _time
      | rename user_name as user
      | stats dc(_raw) as mfa_prompts min(_time) as firstTime max(_time) as lastTime values(user_agent) as user_agent values(src) as src values(dest) as dest
        BY _time user signature
           vendor_account vendor_region vendor_product
           errorMessage
      | where mfa_prompts > 10
      | `security_content_ctime(firstTime)`
      | `security_content_ctime(lastTime)`
      | `aws_multiple_failed_mfa_requests_for_user_filter`
how_to_implement: The Splunk AWS Add-on is required to utilize this data. The search requires AWS CloudTrail logs.
known_false_positives: Multiple Failed MFA requests may also be a sign of authentication or application issues. Filter as needed.
references:
    - https://attack.mitre.org/techniques/T1621/
    - https://aws.amazon.com/what-is/mfa/
intermediate_findings:
    entities:
        - field: user
          type: user
          score: 20
          message: User $user$ is seen to have high number of MFA prompt failures within a short period of time.
threat_objects:
    - field: src
      type: ip_address
analytic_story:
    - AWS Identity and Access Management Account Takeover
asset_type: AWS Account
mitre_attack_id:
    - T1586.003
    - T1621
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: cloud
security_domain: threat

Stages and Predicates

Stage 1: `search`

`cloudtrail` eventName= ConsoleLogin "additionalEventData.MFAUsed"=Yes errorMessage="Failed authentication"

Stage 2: `bucket`

| bucket span=5m _time

Stage 3: `rename`

| rename user_name as user

Stage 4: `stats`

| stats dc(_raw) as mfa_prompts min(_time) as firstTime max(_time) as lastTime values(user_agent) as user_agent values(src) as src values(dest) as dest
    BY _time user signature
       vendor_account vendor_region vendor_product
       errorMessage

Stage 5: `where`

| where mfa_prompts > 10

Stage 6: `search`

| `security_content_ctime(firstTime)`

Stage 7: `search`

| `security_content_ctime(lastTime)`

Stage 8: `search`

| `aws_multiple_failed_mfa_requests_for_user_filter`

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`additionalEventData.MFAUsed`	eq	`Yes`	`field:"additionalEventData.MFAUsed" kind:eq value:"Yes"`
`errorMessage`	eq	`"Failed authentication"`	`field:"aws::errorMessage" kind:eq`
`eventName`	eq	`ConsoleLogin`	`field:"aws::eventName" kind:eq value:"ConsoleLogin"`
`mfa_prompts`	gt	`10`	`field:"mfa_prompts" kind:gt value:"10"`
`sourcetype`	eq	`aws:cloudtrail`	`field:"sourcetype" kind:eq value:"aws:cloudtrail"`

AWS Multiple Failed MFA Requests For User

Known false positives

MITRE ATT&CK coverage

Telemetry coverage

Rules detecting the same action

Rule body

Stages and Predicates

Stage 1: search

Stage 2: bucket

Stage 3: rename

Stage 4: stats

Stage 5: where

Stage 6: search

Stage 7: search

Stage 8: search