THIS IS A DEPRECATED DETECTION
This detection has been marked deprecated by the Splunk Threat Research team. This means that it will no longer be maintained or supported.
This search detects loading of unsigned images by LSASS. Deprecated because too noisy.
- Type: TTP
Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Last Updated: 2019-12-06
- Author: Patrick Bareiss, Splunk
- ID: 56ef054c-76ef-45f9-af4a-a634695dcd65
Kill Chain Phase
- Actions on Objectives
- CIS 8
- CIS 16
1 2 3 4 5 6 `sysmon` EventID=7 Image=*lsass.exe Signed=false | stats count min(_time) as firstTime max(_time) as lastTime by Computer, Image, ImageLoaded, Signed, SHA1 | rename Computer as dest | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `unsigned_image_loaded_by_lsass_filter`
The SPL above uses the following Macros:
unsigned_image_loaded_by_lsass_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
List of fields required to use this analytic.
How To Implement
This search needs Sysmon Logs with a sysmon configuration, which includes EventCode 7 with lsass.exe. This search uses an input macro named
sysmon. We strongly recommend that you specify your environment-specific configurations (index, source, sourcetype, etc.) for Windows Sysmon logs. Replace the macro definition with configurations for your Splunk environment. The search also uses a post-filter macro designed to filter out known false positives.
Known False Positives
Other tools could load images into LSASS for legitimate reason. But enterprise tools should always use signed DLLs.
Associated Analytic Story
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
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