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Description

The following analytic identifies the potential exploitation of a vulnerability (CVE-2023-20198) in the Web User Interface of Cisco IOS XE software. It detects suspicious account creation and subsequent actions, including the deployment of a non-persistent implant configuration file. The detection leverages the Web datamodel, focusing on specific URL patterns and HTTP methods. This activity is significant as it indicates unauthorized administrative access, which can lead to full control of the device. If confirmed malicious, attackers could maintain privileged access, compromising the device's integrity and security.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Web
  • Last Updated: 2024-05-16
  • Author: Michael Haag, Splunk
  • ID: 07c36cda-6567-43c3-bc1a-89dff61e2cd9

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1190 Exploit Public-Facing Application Initial Access
Kill Chain Phase
  • Delivery
NIST
  • DE.CM
CIS20
  • CIS 13
CVE 


1
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| tstats count min(_time) as firstTime max(_time) as lastTime from datamodel=Web where Web.url IN ("/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, sourcetype 
| `drop_dm_object_name("Web")` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)`
| `cisco_ios_xe_implant_access_filter`

Macros

The SPL above uses the following Macros:

:information_source: cisco_ios_xe_implant_access_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required fields

List of fields required to use this analytic.

  • _time
  • Web.http_method
  • Web.url
  • Web.url_length
  • Web.src
  • Web.dest

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, or Splunk for Palo Alto.

Known False Positives

False positives may be present, restrict to Cisco IOS XE devices or perimeter appliances. Modify the analytic as needed based on hunting for successful exploitation of CVE-2023-20198.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
81.0 90 90 Possible exploitation of CVE-2023-20198 against $dest$ by $src$.

:information_source: The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Reference

Test Dataset

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 | version: 2