OneLogin OTP Bruteforce Attack

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

Detects a successful login after multiple failed OTP intents

MITRE ATT&CK coverage

Tactic	Techniques
Credential Access	`T1110` Brute Force

References

https://www.onelogin.com/blog/brute-force-attacks

Rule body

// Copyright 2024 Google LLC. Licensed under Apache-2.0.

rule onelogin_otp_brute_force_attack {

  meta:
    author = "Google Cloud Security"
    description = "Detects a successful login after multiple failed OTP intents"
    rule_id = "mr_cc37e0cf-c8c5-4e46-be0e-b2b992775500"
    rule_name = "OneLogin OTP Bruteforce Attack"
    reference = "https://www.onelogin.com/blog/brute-force-attacks"
    mitre_attack_tactic = "Credential Access"
    mitre_attack_technique = "Brute Force"
    mitre_attack_url = "https://attack.mitre.org/techniques/T1110/"
    mitre_attack_version = "v15.1"
    type = "Alert"
    data_source = "OneLogin"
    severity = "High"
    priority = "High"

  events:
    $failed_otp.metadata.event_type = "USER_RESOURCE_ACCESS"
    $failed_otp.metadata.product_name = "ONELOGIN_SSO"
    $failed_otp.metadata.vendor_name = "ONELOGIN"
    $failed_otp.metadata.product_event_type = "1002" //failed otp challenge
    $failed_otp.principal.user.userid = $userid

    $success_otp.metadata.event_type = "USER_LOGIN"
    $success_otp.metadata.product_name = "ONELOGIN_SSO"
    $success_otp.metadata.vendor_name = "ONELOGIN"
    $success_otp.metadata.product_event_type = "1400" //User verified otp device
    $success_otp.principal.user.userid = $userid

    $login.metadata.event_type = "USER_LOGIN"
    $login.metadata.product_name = "ONELOGIN_SSO"
    $login.metadata.vendor_name = "ONELOGIN"
    $login.metadata.product_event_type = "5" //User logged into onelogin
    $login.principal.user.userid = $userid

    $failed_otp.metadata.event_timestamp.seconds <= $success_otp.metadata.event_timestamp.seconds
    $success_otp.metadata.event_timestamp.seconds <= $login.metadata.event_timestamp.seconds

  match:
    $userid over 15m

  outcome:
    $risk_score = max(75)
    $mitre_attack_tactic = "Credential Access"
    $mitre_attack_technique = "Brute Force"
    $target_user_agent = array_distinct($login.network.http.user_agent)
    $principal_ip = array_distinct($login.principal.ip)
    $principal_ip_country = array_distinct($login.principal.ip_geo_artifact.location.country_or_region)
    $principal_ip_state = array_distinct($login.principal.ip_geo_artifact.location.state)
    $principal_user_user_display_name = array_distinct($login.principal.user.user_display_name)
    $target_user_userid = array_distinct($login.target.user.userid)
    $otp_device_name = array_distinct($success_otp.additional.fields["otp_device_name"])
    $otp_device_id = array_distinct($success_otp.principal.asset_id)

  condition:
    #failed_otp >= 4 and $success_otp and $login
}

YARA-L rule structure

Condition

Fires when $failed_otp occurs at least 4 times in the 15m window and at least one $success_otp event in the 15m window and at least one $login event in the 15m window.

Events

`$failed_otp` `USER_RESOURCE_ACCESS` (`1002`)

metadata.product_event_type = "1002"

`$success_otp` `USER_LOGIN` (`1400`)

metadata.product_event_type = "1400"

`$login` `USER_LOGIN`

metadata.product_event_type = "5"

Match and correlation

Order: $failed_otp before $success_otp; $success_otp before $login
Match key: $userid (principal.user.userid)
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(75)`
`target_user_agent`	`array_distinct($login.network.http.user_agent)`
`principal_ip`	`array_distinct($login.principal.ip)`
`principal_ip_country`	`array_distinct($login.principal.ip_geo_artifact.location.country_or_region)`
`principal_ip_state`	`array_distinct($login.principal.ip_geo_artifact.location.state)`
`principal_user_user_display_name`	`array_distinct($login.principal.user.user_display_name)`
`target_user_userid`	`array_distinct($login.target.user.userid)`
`otp_device_name`	`array_distinct($success_otp.additional.fields["otp_device_name"])`
`otp_device_id`	`array_distinct($success_otp.principal.asset_id)`