Detection rules › Splunk
Cisco Duo Bypass Code Generation
The following analytic detects when a Duo user generates a bypass code, which allows them to circumvent multi-factor authentication (2FA) protections. It works by monitoring Duo activity logs for the 'bypass_create' action, renaming the affected object as the user, and aggregating events to identify instances where a bypass code is issued. This behavior is significant for a Security Operations Center (SOC) because generating a bypass code can enable attackers, malicious insiders, or unauthorized administrators to gain access to sensitive systems without the required second authentication factor. Such activity may indicate account compromise, privilege abuse, or attempts to weaken security controls. Early detection of bypass code generation is critical, as it allows the SOC to investigate and respond before an attacker can exploit the reduced authentication requirements, helping to prevent unauthorized access, data breaches, or further lateral movement within the environment. Monitoring for this action helps maintain strong authentication standards and reduces the risk of credential-based attacks.
Known false positives
- No false positives have been identified at this time.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Persistence | |
| Defense Impairment | |
| Credential Access |
Rule body
name: Cisco Duo Bypass Code Generation
id: 446e81ff-ce06-4925-9c7d-4073f9b5abf5
version: 6
creation_date: '2025-07-10'
modification_date: '2026-05-13'
author: Patrick Bareiss, Splunk
status: production
type: TTP
description: |
The following analytic detects when a Duo user generates a bypass code, which allows them to circumvent multi-factor authentication (2FA) protections.
It works by monitoring Duo activity logs for the 'bypass_create' action, renaming the affected object as the user, and aggregating events to identify
instances where a bypass code is issued. This behavior is significant for a Security Operations Center (SOC) because generating a bypass code can enable
attackers, malicious insiders, or unauthorized administrators to gain access to sensitive systems without the required second authentication factor.
Such activity may indicate account compromise, privilege abuse, or attempts to weaken security controls. Early detection of bypass code generation is
critical, as it allows the SOC to investigate and respond before an attacker can exploit the reduced authentication requirements, helping to prevent
unauthorized access, data breaches, or further lateral movement within the environment. Monitoring for this action helps maintain strong authentication
standards and reduces the risk of credential-based attacks.
data_source:
- Cisco Duo Administrator
search: |-
`cisco_duo_administrator` action=bypass_create
| rename object as user
| stats count min(_time) as firstTime max(_time) as lastTime
BY action actionlabel description
user
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `cisco_duo_bypass_code_generation_filter`
how_to_implement: The analytic leverages Duo activity logs to be ingested using the Cisco Security Cloud App (https://splunkbase.splunk.com/app/7404).
known_false_positives: No false positives have been identified at this time.
references:
- https://splunkbase.splunk.com/app/7404
finding:
title: A user $user$ has generated a bypass code
entity:
field: user
type: user
score: 50
analytic_story:
- Cisco Duo Suspicious Activity
asset_type: Identity
mitre_attack_id:
- T1556
product:
- Splunk Enterprise
- Splunk Enterprise Security
- Splunk Cloud
category: application
security_domain: identity
Stages and Predicates
Stage 1: search
`cisco_duo_administrator` action=bypass_create
Stage 2: rename
| rename object as user
Stage 3: stats
| stats count min(_time) as firstTime max(_time) as lastTime
BY action actionlabel description
user
Stage 4: search
| `security_content_ctime(firstTime)`
Stage 5: search
| `security_content_ctime(lastTime)`
Stage 6: search
| `cisco_duo_bypass_code_generation_filter`
Indicators
These rows show field, operator, and value matches.
| Field | Kind | Values | Search |
|---|---|---|---|
action | eq |
| field:"action" kind:eq value:"bypass_create" |
sourcetype | eq |
| field:"sourcetype" kind:eq value:"cisco:duo:administrator" |