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Description

The following analytic detects attempts to exploit the ConnectWise ScreenConnect CVE-2024-1709 vulnerability, which allows attackers to bypass authentication via alternate paths or channels. It leverages Nginx access logs to identify web requests to the SetupWizard.aspx page, indicating potential exploitation. This activity is significant as it can lead to unauthorized administrative access and remote code execution. If confirmed malicious, attackers could create administrative users and gain full control over the affected ScreenConnect instance, posing severe security risks. Immediate remediation by updating to version 23.9.8 or above is recommended.

  • Type: TTP

  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud

  • Last Updated: 2024-05-16
  • Author: Michael Haag, Splunk
  • ID: b3f7a803-e802-448b-8eb2-e796b223bccc

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
2
3
4
5



`nginx_access_logs` uri_path IN ("*/SetupWizard.aspx/*","*/SetupWizard/") status=200 http_method=POST  
| stats count min(_time) as firstTime max(_time) as lastTime by src, dest, http_user_agent, url, uri_path, status, http_method, sourcetype, source 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `nginx_connectwise_screenconnect_authentication_bypass_filter`

Macros

The SPL above uses the following Macros:

:information_source: nginx_connectwise_screenconnect_authentication_bypass_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
  • src
  • dest
  • http_user_agent
  • url
  • uri_path
  • status
  • http_method
  • sourcetype
  • source

How To Implement

To implement this analytic, ensure proper logging is occurring with Nginx, access.log and error.log, and that these logs are being ingested into Splunk. STRT utilizes this nginx.conf https://gist.github.com/MHaggis/26f59108b04da8f1d870c9cc3a3c8eec to properly log as much data with Nginx.

Known False Positives

False positives are not expected, as the detection is based on the presence of web requests to the SetupWizard.aspx page, which is not a common page to be accessed by legitimate users. Note that the analytic is limited to HTTP POST and a status of 200 to reduce false positives. Modify the query as needed to reduce false positives or hunt for additional indicators of compromise.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
100.0 100 100 An authentication bypass attempt against ScreenConnect has been detected on $dest$.

: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