Detection: Cisco IOS XE Implant Access

Updated Date: 2026-03-27 ID: 07c36cda-6567-43c3-bc1a-89dff61e2cd9 Author: Michael Haag, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic identifies the potential exploitation of the Cisco IOS XE vulnerability, CVE-2023-20198, in the Web User Interface. It monitors POST requests to the "/webui/logoutconfirm.html?logon_hash=*" endpoint using the Web datamodel. This activity can be significant as it indicates potential access request to the implant If confirmed malicious, attackers could maintain privileged access, compromising the device's integrity and security.

Search

 1
 2| tstats `security_content_summariesonly`
 3  count min(_time) as firstTime
 4        max(_time) as lastTime
 5
 6FROM datamodel=Web WHERE
 7
 8Web.url="*/webui/logoutconfirm.html?logon_hash=*"
 9Web.http_method=POST
10Web.status=200
11
12BY Web.http_user_agent Web.status Web.http_method
13   Web.url Web.url_length Web.src Web.dest
14
15| `drop_dm_object_name("Web")`
16
17| `security_content_ctime(firstTime)`
18
19| `security_content_ctime(lastTime)`
20
21| `cisco_ios_xe_implant_access_filter`

Data Source

Name	Platform	Sourcetype	Source
Suricata	Other	`'suricata'`	`'not_applicable'`

Macros Used

Name	Value
security_content_ctime	`convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)`
cisco_ios_xe_implant_access_filter	`search *`

cisco_ios_xe_implant_access_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
T1190	Exploit Public-Facing Application	Initial Access

Delivery

DE.CM

CIS 13

CVE

CVE-2023-20198

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

This detection requires the Web datamodel to be populated from a supported Technology Add-On like Splunk for Apache, Splunk for Nginx, Suricata, or Splunk for Palo Alto.

Known False Positives

False positives may be present from vulnerability scanners or legitimate access requests. Apply appropriate filters as needed.

Associated Analytic Story

Cisco IOS XE Software Web Management User Interface vulnerability

Risk Based Analytics (RBA)

Risk Message:

Possible exploitation of CVE-2023-20198 against $dest$ via $url$ by $src$.

Risk Object	Risk Object Type	Risk Score	Threat Objects
dest	system	50	src

References

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	✅ Passing	N/A	N/A	N/A
Unit	✅ Passing	Dataset	`not_applicable`	`suricata`
Integration	✅ Passing	Dataset	`not_applicable`	`suricata`

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: 8