Try in Splunk Security Cloud


Cisco has identified active exploitation of a previously unknown vulnerability in the Web User Interface (Web UI) feature of Cisco IOS XE software (CVE-2023-20198) when exposed to the internet or untrusted networks. Successful exploitation of this vulnerability allows an attacker to create an account on the affected device with privilege level 15 access, effectively granting them full control of the compromised device and allowing possible subsequent unauthorized activity.

  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Web
  • Last Updated: 2023-10-17
  • Author: Michael Haag, Splunk
  • ID: b5394b6a-b774-4bb6-a2bc-98f98cf7be88


Cisco discovered early evidence of potentially malicious activity on September 28, 2023, when a case was opened with Cisco’s Technical Assistance Center (TAC) that identified unusual behavior on a customer device. Upon further investigation, they observed what they have determined to be related activity as early as September 18. The activity included an authorized user creating a local user account under the username cisco_tac_admin from a suspicious IP address. On October 12, Cisco Talos Incident Response (Talos IR) and TAC detected what they later determined to be an additional cluster of related activity that began on that same day. In this cluster, an unauthorized user was observed creating a local user account under the name cisco_support from a second suspicious IP address. Unlike the September case, this October activity included several subsequent actions, including the deployment of an implant consisting of a configuration file (cisco_service.conf). The configuration file defines the new web server endpoint (URI path) used to interact with the implant. That endpoint receives certain parameters, described in more detail below, that allows the actor to execute arbitrary commands at the system level or IOS level. For the implant to become active, the web server must be restarted; in at least one observed case the server was not restarted so the implant never became active despite being installed.


Name Technique Type
Cisco IOS XE Implant Access Exploit Public-Facing Application TTP


source | version: 1