Detection: Cisco Duo Bypass Code Generation

Updated Date: 2025-07-08 ID: 446e81ff-ce06-4925-9c7d-4073f9b5abf5 Author: Patrick Bareiss, Splunk Type: TTP Product: Splunk Enterprise Security

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.

Search

1`cisco_duo_administrator` action=bypass_create 
2| rename object as user 
3| stats count min(_time) as firstTime max(_time) as lastTime by action actionlabel description user 
4| `security_content_ctime(firstTime)` 
5| `security_content_ctime(lastTime)` 
6| `cisco_duo_bypass_code_generation_filter`

Data Source

Name	Platform	Sourcetype	Source
Cisco Duo Administrator	N/A	`'cisco:duo:administrator'`	`'cisco_duo'`

Macros Used

Name	Value
cisco_duo_administrator	`sourcetype=cisco:duo:administrator`
cisco_duo_bypass_code_generation_filter	`search *`

cisco_duo_bypass_code_generation_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK

+ Kill Chain Phases

+ NIST

+ CIS

- Threat Actors

ID	Technique	Tactic
T1556	Modify Authentication Process	Credential Access

Exploitation

Installation

DE.CM

CIS 10

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Setting	Value
Disabled	true
Cron Schedule	`0 * * * *`
Earliest Time	`-70m@m`
Latest Time	`-10m@m`
Schedule Window	`auto`
Creates Notable	Yes
Rule Title	`%name%`
Rule Description	`%description%`
Notable Event Fields	user, dest
Creates Risk Event	True

This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.

Implementation

The analytic leverages Duo activity logs to be ingested using the Cisco Security Cloud App (https://splunkbase.splunk.com/app/7404).

Known False Positives

unknown

Associated Analytic Story

Cisco Duo Suspicious Activity

Risk Based Analytics (RBA)

Risk Message:

A user $user$ has generated a bypass code

Risk Object	Risk Object Type	Risk Score	Threat Objects
user	user	48	No Threat Objects

References

https://splunkbase.splunk.com/app/7404

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	✅ Passing	N/A	N/A	N/A
Unit	✅ Passing	Dataset	`duo`	`cisco:duo:administrator`
Integration	✅ Passing	Dataset	`duo`	`cisco:duo:administrator`

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

Source: GitHub | Version: 1