Windows Rundll32 WebDav With Network Connection

Name:Windows Rundll32 WebDav With Network Connection
id:f03355e0-28b5-4e9b-815a-6adffc63b38c
version:6
date:2024-11-13
author:Michael Haag, Splunk
status:experimental
type:TTP
Description:The following analytic detects the execution of rundll32.exe with command-line arguments loading davclnt.dll and the davsetcookie function to access a remote WebDav instance. It uses data from Endpoint Detection and Response (EDR) agents, correlating process execution and network traffic data. This activity is significant as it may indicate exploitation of CVE-2023-23397, a known vulnerability. If confirmed malicious, this could allow an attacker to establish unauthorized remote connections, potentially leading to data exfiltration or further network compromise.
Data_source:

search:| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Processes where Processes.parent_process_name=svchost.exe `process_rundll32` Processes.process IN ("*\\windows\\system32\\davclnt.dll,*davsetcookie*", "*\\windows\\syswow64\\davclnt.dll,*davsetcookie*") by host _time span=1h Processes.process_id Processes.process_name Processes.dest Processes.process_path Processes.process Processes.parent_process_name Processes.parent_process
| `drop_dm_object_name(Processes)`
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| rename dest as src
| join host process_id [
| tstats `security_content_summariesonly` count latest(All_Traffic.dest) as dest latest(All_Traffic.dest_ip) as dest_ip latest(All_Traffic.dest_port) as dest_port FROM datamodel=Network_Traffic.All_Traffic where All_Traffic.dest_port!=0 NOT (All_Traffic.dest_ip IN (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16)) by host All_Traffic.process_id
| `drop_dm_object_name(All_Traffic)`]
| `windows_rundll32_webdav_with_network_connection_filter`

how_to_implement:The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the `Processes` node of the `Endpoint` data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.
known_false_positives:False positives will be present based on legitimate software, filtering may need to occur.
References:
  -https://strontic.github.io/xcyclopedia/library/davclnt.dll-0EA3050E7CC710526E330C413C165DA0.html
  -https://twitter.com/ACEResponder/status/1636116096506818562?s=20
  -https://twitter.com/domchell/status/1635999068282408962?s=20
  -https://msrc.microsoft.com/blog/2023/03/microsoft-mitigates-outlook-elevation-of-privilege-vulnerability/
  -https://www.pwndefend.com/2023/03/15/the-long-game-persistent-hash-theft/
drilldown_searches:
  :
tags:
  analytic_story:
    - 'CVE-2023-23397 Outlook Elevation of Privilege'
  asset_type:Endpoint
  cve:
    - 'CVE-2023-23397'
  mitre_attack_id:
    - 'T1048.003'
  product:
    - 'Splunk Enterprise'
    - 'Splunk Enterprise Security'
    - 'Splunk Cloud'
  security_domain:endpoint

tests:
 name:'True Positive Test'
 attack_data:
  data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1048.003/cve-2023-23397/webdav_windows-sysmon.log
  source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
  sourcetype: XmlWinEventLog
manual_test:None