ID | Technique | Tactic |
---|---|---|
T1587.003 | Digital Certificates | Resource Development |
Detection: Splunk Digital Certificates Lack of Encryption
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.
Search
1`splunkd` group="tcpin_connections" ssl="false"
2| stats values(sourceIp) latest(fwdType) latest(version) by hostname
3| `splunk_digital_certificates_lack_of_encryption_filter`
Data Source
Name | Platform | Sourcetype | Source | Supported App |
---|---|---|---|---|
Splunk | Splunk | 'splunkd_ui_access' |
'splunkd_ui_access.log' |
N/A |
Macros Used
Name | Value |
---|---|
splunkd | index=_internal sourcetype=splunkd |
splunk_digital_certificates_lack_of_encryption_filter | search * |
splunk_digital_certificates_lack_of_encryption_filter
is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Annotations
Default Configuration
This detection is configured by default in Splunk Enterprise Security to run with the following settings:
Setting | Value |
---|---|
Disabled | true |
Cron Schedule | 0 * * * * |
Earliest Time | -70m@m |
Latest Time | -10m@m |
Schedule Window | auto |
Creates Risk Event | True |
Implementation
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
Risk Based Analytics (RBA)
Risk Message | Risk Score | Impact | Confidence |
---|---|---|---|
$hostname$ is not using TLS when forwarding data | 20 | 25 | 80 |
References
-
https://www.splunk.com/en_us/product-security/announcements/svd-2022-0607.html
-
https://www.splunk.com/en_us/product-security/announcements/svd-2022-0601.html
-
https://www.github.com/splunk/security_content/blob/develop/workbooks/splunk_psa_0622.json
Detection Testing
Test Type | Status | Dataset | Source | Sourcetype |
---|---|---|---|---|
Validation | ✅ Passing | N/A | N/A | N/A |
Unit | ✅ Passing | Dataset | /opt/splunk/var/log/splunk/metrics.log |
splunkd |
Integration | ✅ Passing | Dataset | /opt/splunk/var/log/splunk/metrics.log |
splunkd |
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: GitHub | Version: 2