This apps main function is to enable a custom Splunk search command to reconstruct a pstree from Sysmon process creation events (EventCode 1). Information from memory forensics, such as Volatility's pstree, can be very helpful to detect malicious processes. By ingesting Sysmon events in Splunk and using this command you can quickly get similar information without performing memory forensics.
- Ingest Process Creation Events with Parent Process information in Splunk
There are several ways to implement the command. Here are two:
- Install from file - Click "Clone or Download" then "Download Zip". The tgz file in repo can be used with Splunk's "Install App from File"
- Copy splunk_pstree_app directory to etc - Clone the repo, then copy "splunk_pstree_app" directory to $SPLUNK_HOME/etc/apps
Installation by copying directory will require a restart of splunkd.
The pstree command requires two arguments, child and parent. The command is intended for sysmon EventCode=1 events but can be used for anything. The command returns a row for each root value with a multivalue field, "tree", containing the root value and all childern values.
Note: Fields passed as arguments to the pstree command must be referenced before calling pstree. The simplest way to ensure this is to include "| fields *" prior to piping to pstree. Thanks to spitzd for discovering.
Simple Sysmon Usage
index=sysmon EventCode=1 host=victim_machine
| fields *
| pstree child=Image parent=ParentImage
| table tree
Pretty Sysmon Usage
index=sysmon EventCode=1 host=victim_machine
| rex field=ParentImage "\x5c(?<ParentName>[^\x5c]+)$"
| rex field=Image "\x5c(?<ProcessName>[^\x5c]+)$"
| eval parent = ParentName." (".ParentProcessId.")"
| eval child = ProcessName." (".ProcessId.")"
| eval detail=strftime(_time,"%Y-%m-%d %H:%M:%S")." ".CommandLine
| pstree child=child parent=parent detail=detail spaces=50
| table tree
Searching for tree with specific process
index=sysmon EventCode=1 host=victim_machine
| fields *
| pstree child=Image parent=ParentImage
| search tree=*<process name>*
| table tree
Use legacy recursive method (By default iterative algorithm method="i" used now)
index=sysmon EventCode=1 host=victim_machine
| fields *
| pstree child=Image parent=ParentImage method="r"
| table tree