Cisco IOS XE Implant Access

name: Cisco IOS XE Implant Access
id: 07c36cda-6567-43c3-bc1a-89dff61e2cd9
version: 10
creation_date: '2023-10-17'
modification_date: '2026-05-13'
author: Michael Haag, Splunk
status: production
type: TTP
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.
data_source:
    - Suricata
search: |-
    | tstats `security_content_summariesonly`
      count min(_time) as firstTime
            max(_time) as lastTime
    
    FROM datamodel=Web WHERE
    
    Web.url="*/webui/logoutconfirm.html?logon_hash=*"
    Web.http_method=POST
    Web.status=200
    
    BY Web.http_user_agent Web.status Web.http_method
       Web.url Web.url_length Web.src Web.dest
    | `drop_dm_object_name("Web")`
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `cisco_ios_xe_implant_access_filter`
how_to_implement: |-
    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.
references:
    - https://blog.talosintelligence.com/active-exploitation-of-cisco-ios-xe-software/
    - https://github.com/vulncheck-oss/cisco-ios-xe-implant-scanner
finding:
    title: Possible exploitation of CVE-2023-20198 against $dest$ via $url$ by $src$.
    entity:
        field: dest
        type: system
        score: 50
threat_objects:
    - field: src
      type: ip_address
analytic_story:
    - Cisco IOS XE Software Web Management User Interface vulnerability
asset_type: Network
cve:
    - CVE-2023-20198
mitre_attack_id:
    - T1190
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: web
security_domain: network