Detection: Cisco Duo Policy Bypass 2FA

Updated Date: 2025-07-08 ID: 65862e8a-799a-4509-ae1c-4602aa139580 Author: Patrick Bareiss, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects instances where a Duo policy is created or updated to allow access without two-factor authentication (2FA). It identifies this behavior by searching Duo administrator activity logs for policy changes that set the authentication status to "Allow access without 2FA." By monitoring for these specific actions, the analytic highlights potential attempts to weaken authentication controls, which could be indicative of malicious activity or insider threats. This behavior is critical for a SOC to identify, as bypassing 2FA significantly reduces the security posture of an organization, making it easier for attackers to gain unauthorized access to sensitive systems and data. Detecting and responding to such policy changes promptly helps prevent potential account compromise and mitigates the risk of broader security breaches.

Search

1`cisco_duo_administrator` action=policy_update OR action=policy_create 
2| spath input=description 
3| search auth_status="Allow access without 2FA" 
4| rename object as user 
5| stats count min(_time) as firstTime max(_time) as lastTime by action actionlabel description user admin_email 
6| `security_content_ctime(firstTime)` 
7| `security_content_ctime(lastTime)` 
8| `cisco_duo_policy_bypass_2fa_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_policy_bypass_2fa_filter	`search *`

cisco_duo_policy_bypass_2fa_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 policy has been created or updated to allow access without 2FA by user $user$ with email $admin_email$

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