The following analytic identifies a process requesting access in winlogon.exe to duplicate its handle with a non-common or public process source path. This technique was seen where adversaries attempt to gain privileges to their process. This duplicate handle access technique, may refer to a malicious process duplicating the process token of winlogon.exe and using it to a new process instance. Winlogon.exe is the common targeted process of this technique because it contains high privileges and security tokens.
- Type: Anomaly
Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Last Updated: 2022-08-24
- Author: Teoderick Contreras, Splunk
- ID: b8f7ed6b-0556-4c84-bffd-839c262b0278
Kill Chain Phase
- CIS 3
- CIS 5
- CIS 16
1 2 3 4 5 `sysmon` EventCode=10 TargetImage IN("*\\system32\\winlogon.exe*", "*\\SysWOW64\\winlogon.exe*") AND GrantedAccess = 0x1040 AND NOT (SourceImage IN("C:\\Windows\\*", "C:\\Program File*", "%systemroot%\\*")) | stats count min(_time) as firstTime max(_time) as lastTime by SourceImage TargetImage SourceProcessGUID TargetProcessGUID SourceProcessId TargetProcessId GrantedAccess CallTrace | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `windows_access_token_winlogon_duplicate_handle_in_uncommon_path_filter`
The SPL above uses the following Macros:
windows_access_token_winlogon_duplicate_handle_in_uncommon_path_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
To successfully implement this search, you must be ingesting data that records process activity from your hosts to populate the endpoint data model in the processes node. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA.
Known False Positives
It is possible legitimate applications will request access to winlogon, filter as needed.
Associated Analytic Story
|49.0||70||70||a process $SourceImage$ is duplicating the handle token of winlogon.exe in $Computer$|
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
source | version: 1