Detection rules › Splunk
AWS High Number Of Failed Authentications For User
The following analytic detects an AWS account experiencing more than 20 failed authentication attempts within a 5-minute window. It leverages AWS CloudTrail logs to identify multiple failed ConsoleLogin events. This behavior is significant as it may indicate a brute force attack targeting the account. If confirmed malicious, the attacker could potentially gain unauthorized access, leading to data breaches or further exploitation of the AWS environment. Security teams should consider adjusting the threshold based on their specific environment to reduce false positives.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Discovery | T1201 Password Policy Discovery |
Rules detecting the same action
Other rules on this platform that filter on the same API call or 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 From Ip (Splunk)
- AWS Multiple Failed MFA Requests For User (Splunk)
- AWS Multiple Users Failing To Authenticate From Ip (Splunk)
Rule body splunk
name: AWS High Number Of Failed Authentications For User
id: e3236f49-daf3-4b70-b808-9290912ac64d
version: 10
creation_date: '2023-01-27'
modification_date: '2026-05-13'
author: Bhavin Patel, Splunk
status: production
type: Anomaly
description: The following analytic detects an AWS account experiencing more than 20 failed authentication attempts within a 5-minute window. It leverages AWS CloudTrail logs to identify multiple failed ConsoleLogin events. This behavior is significant as it may indicate a brute force attack targeting the account. If confirmed malicious, the attacker could potentially gain unauthorized access, leading to data breaches or further exploitation of the AWS environment. Security teams should consider adjusting the threshold based on their specific environment to reduce false positives.
data_source:
- AWS CloudTrail ConsoleLogin
search: |-
`cloudtrail` eventName=ConsoleLogin action=failure
| bucket span=10m _time
| rename user_name as user
| stats dc(_raw) AS failed_attempts values(src) as src values(user_agent) as user_agent
BY _time, user, signature,
dest, vendor_account vendor_region,
vendor_product
| where failed_attempts > 20
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `aws_high_number_of_failed_authentications_for_user_filter`
how_to_implement: You must install Splunk AWS Add on and Splunk App for AWS. This search works with AWS CloudTrail logs.
known_false_positives: A user with more than 20 failed authentication attempts in the span of 5 minutes may also be triggered by a broken application.
references:
- https://www.trendmicro.com/cloudoneconformity/knowledge-base/aws/IAM/password-policy.html
drilldown_searches:
- name: View the detection results for - "$user$"
search: '%original_detection_search% | search user = "$user$"'
earliest_offset: $info_min_time$
latest_offset: $info_max_time$
- name: View risk events for the last 7 days for - "$user$"
search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$user$") | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
earliest_offset: 7d
latest_offset: "0"
intermediate_findings:
entities:
- field: user
type: user
score: 20
message: User $user$ failed to authenticate more than 20 times in the span of 5 minutes for AWS Account $vendor_account$
analytic_story:
- Compromised User Account
- AWS Identity and Access Management Account Takeover
asset_type: AWS Account
mitre_attack_id:
- T1201
product:
- Splunk Enterprise
- Splunk Enterprise Security
- Splunk Cloud
category: cloud
security_domain: threat
tests:
- name: True Positive Test
attack_data:
- data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1110.003/aws_multiple_login_fail_per_user/cloudtrail.json
sourcetype: aws:cloudtrail
source: aws_cloudtrail
test_type: unit
Stages and Predicates
Stage 1: search
`cloudtrail` eventName=ConsoleLogin action=failure
Stage 2: bucket
| bucket span=10m _time
Stage 3: rename
| rename user_name as user
Stage 4: stats
| stats dc(_raw) AS failed_attempts values(src) as src values(user_agent) as user_agent
BY _time, user, signature,
dest, vendor_account vendor_region,
vendor_product
Stage 5: where
| where failed_attempts > 20
Stage 6: search
| `security_content_ctime(firstTime)`
Stage 7: search
| `security_content_ctime(lastTime)`
Stage 8: search
| `aws_high_number_of_failed_authentications_for_user_filter`
Indicators
Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.
| Field | Kind | Values |
|---|---|---|
action | eq |
|
eventName | eq |
|
failed_attempts | gt |
|
sourcetype | eq |
|