AWS Successful Login After Multiple Failed Attempts

Severity: medium
Type: Alert
Time window: 15m
Match by: user
Author: Google Cloud Security
Source: github.com/chronicle/detection-rules

Detects successful login after multiple failed attempts

MITRE ATT&CK coverage

Tactic	Techniques
Initial Access	`T1078` Valid Accounts
Persistence	`T1078` Valid Accounts
Privilege Escalation	`T1078` Valid Accounts
Stealth	`T1078` Valid Accounts

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.

Rule body

// Copyright 2023 Google LLC. Licensed under Apache-2.0.

rule aws_successful_login_after_multiple_failed_attempts {

  meta:
    author = "Google Cloud Security"
    description = "Detects successful login after multiple failed attempts"
    rule_id = "mr_8ba028b6-98e3-4983-92e9-c0fe50419a20"
    rule_name = "AWS Successful Login After Multiple Failed Attempts"
    mitre_attack_tactic = "Defense Evasion, Persistence, Privilege Escalation, Initial Access"
    mitre_attack_technique = "Valid Accounts"
    mitre_attack_url = "https://attack.mitre.org/techniques/T1078/"
    mitre_attack_version = "v13.1"
    type = "Alert"
    data_source = "AWS CloudTrail"
    platform = "AWS"
    severity = "Medium"
    priority = "Medium"

  events:
    $fail.metadata.vendor_name = "AMAZON"
    $fail.metadata.product_name = "AWS CloudTrail"
    $fail.metadata.event_type = "USER_LOGIN"
    $fail.metadata.product_event_type = "ConsoleLogin"
    $fail.security_result.action = "BLOCK"
    $fail.security_result.description = "Reason: Failed authentication"
    $fail.target.user.user_display_name = $user

    $success.metadata.vendor_name = "AMAZON"
    $success.metadata.product_name = "AWS CloudTrail"
    $success.metadata.event_type = "USER_LOGIN"
    $success.metadata.product_event_type = "ConsoleLogin"
    $success.security_result.action = "ALLOW"
    $success.security_result.summary = "Login to AWS Console succeeded."
    $success.target.user.user_display_name = $user

    $success.metadata.event_timestamp.seconds > $fail.metadata.event_timestamp.seconds

  match:
    $user over 15m

  outcome:
    $risk_score = max(
        // Country mismatch
        if($fail.principal.ip_geo_artifact.location.country_or_region = $success.principal.ip_geo_artifact.location.country_or_region, 40) +
        // Unauthorized geographies
        if($success.principal.ip_geo_artifact.location.country_or_region = "Cuba", 10) +
        if($success.principal.ip_geo_artifact.location.country_or_region = "Iran", 10) +
        if($success.principal.ip_geo_artifact.location.country_or_region = "North Korea" , 10) +
        if($success.principal.ip_geo_artifact.location.country_or_region = "Russia", 10) +
        if($success.principal.ip_geo_artifact.location.country_or_region = "Syria", 10)
    )
    $mitre_attack_tactic = "Defense Evasion, Persistence, Privilege Escalation, Initial Access"
    $mitre_attack_technique = "Valid Accounts"
    $mitre_attack_technique_id = "T1078"
    $event_count = count_distinct($success.metadata.id) + count_distinct($fail.metadata.id)
    $principal_ip = array_distinct($success.principal.ip)
    $principal_ip_country = array_distinct($success.principal.ip_geo_artifact.location.country_or_region)
    $principal_ip_state = array_distinct($success.principal.ip_geo_artifact.location.state)
    $target_user_userid = array_distinct($success.target.user.userid)
    $is_mfa_used = array_distinct($success.extensions.auth.auth_details)
    $target_resource_name = array_distinct($success.target.resource.name)
    $target_resource_product_object_id = array_distinct($success.target.resource.product_object_id)

  condition:
    #fail > 3 and $success
}

YARA-L rule structure

Condition

Fires when $fail occurs more than 3 times in the 15m window and at least one $success event in the 15m window.

Events

`$fail` `USER_LOGIN`

metadata.product_event_type = "ConsoleLogin"
security_result.action = "BLOCK"
security_result.description = "Reason: Failed authentication"

`$success` `USER_LOGIN`

metadata.product_event_type = "ConsoleLogin"
security_result.action = "ALLOW"
security_result.summary = "Login to AWS Console succeeded."

Match and correlation

Order: $fail before $success
Match key: $user (target.user.user_display_name)
Within: 15m

Outcome

Outcome variables add context to a detection. When the rule generates an alert, $risk_score is displayed with it.

Field	Expression
`risk_score`	max( if($fail.principal.ip_geo_artifact.location.country_or_region = $success.principal.ip_geo_artifact.location.country_or_region, 40) + if($success.principal.ip_geo_artifact.location.country_or_region = "Cuba", 10) + if($success.principal.ip_geo_artifact.location.country_or_region = "Iran", 10) + if($success.principal.ip_geo_artifact.location.country_or_region = "North Korea" , 10) + if($success.principal.ip_geo_artifact.location.country_or_region = "Russia", 10) + if($success.principal.ip_geo_artifact.location.country_or_region = "Syria", 10) )
`event_count`	`count_distinct($success.metadata.id) + count_distinct($fail.metadata.id)`
`principal_ip`	`array_distinct($success.principal.ip)`
`principal_ip_country`	`array_distinct($success.principal.ip_geo_artifact.location.country_or_region)`
`principal_ip_state`	`array_distinct($success.principal.ip_geo_artifact.location.state)`
`target_user_userid`	`array_distinct($success.target.user.userid)`
`is_mfa_used`	`array_distinct($success.extensions.auth.auth_details)`
`target_resource_name`	`array_distinct($success.target.resource.name)`
`target_resource_product_object_id`	`array_distinct($success.target.resource.product_object_id)`