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Description

The following analytic identifies Splunk forwarder connections that are not using TLS encryption. It leverages data from the splunkd logs, specifically looking for connections where the ssl field is set to "false". This activity is significant because unencrypted connections can expose sensitive data and allow unauthorized access, posing a security risk. If confirmed malicious, an attacker could exploit this vulnerability to download or publish forwarder bundles, potentially leading to arbitrary code execution and further compromise of the environment.

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

  • Last Updated: 2024-05-18
  • Author: Lou Stella, Splunk
  • ID: 386a7ebc-737b-48cf-9ca8-5405459ed508

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1587.003 Digital Certificates Resource Development
Kill Chain Phase
  • Weaponization
NIST
  • DE.AE
CIS20
  • CIS 10
CVE
1
2
3
`splunkd` group="tcpin_connections" ssl="false" 
| stats values(sourceIp) latest(fwdType) latest(version) by hostname 
| `splunk_digital_certificates_lack_of_encryption_filter`

Macros

The SPL above uses the following Macros:

:information_source: splunk_digital_certificates_lack_of_encryption_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.

  • group
  • ssl
  • sourceIp
  • fwdType
  • version
  • hostname

How To Implement

This anomaly search looks for forwarder connections that are not currently using TLS. It then presents the source IP, the type of forwarder, and the version of the forwarder. You can also remove the "ssl=false" argument from the initial stanza in order to get a full list of all your forwarders that are sending data, and the version of Splunk software they are running, for audit purposes. Splunk SOAR customers can find a SOAR workbook that walks an analyst through the process of running these hunting searches in the references list of this detection. In order to use this workbook, a user will need to run a curl command to post the file to their SOAR instance such as "curl -u username:password https://soar.instance.name/rest/rest/workbook_template -d @splunk_psa_0622.json". A user should then create an empty container or case, attach the workbook, and begin working through the tasks.

Known False Positives

None at this time

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
20.0 25 80 $hostname$ is not using TLS when forwarding data

: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