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splunk-security_content/detections/endpoint/batch_file_write_to_system32.yml
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YAML

name: Batch File Write to System32
id: 503d17cb-9eab-4cf8-a20e-01d5c6987ae3
version: 4
date: '2023-4-11'
author: Steven Dick, Michael Haag, Rico Valdez, Splunk
status: production
type: TTP
description: The search looks for a batch file (.bat) written to the Windows system
directory tree.
data_source:
- Sysmon Event ID 1
search: '| tstats `security_content_summariesonly` count FROM datamodel=Endpoint.Processes where
Processes.process_name=* by _time span=1h Processes.process_guid Processes.process_name Processes.dest Processes.user
| `drop_dm_object_name(Processes)` | join process_guid
[| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Filesystem
where Filesystem.file_path IN ("*\\system32\\*", "*\\syswow64\\*") Filesystem.file_name="*.bat" by _time span=1h Filesystem.dest Filesystem.file_create_time Filesystem.file_name Filesystem.file_path Filesystem.process_guid
| `drop_dm_object_name(Filesystem)`]
| table dest user file_create_time, file_name, file_path, process_name, firstTime, lastTime
| dedup file_create_time
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `batch_file_write_to_system32_filter`'
how_to_implement: To successfully implement this search you need to be ingesting information
on process that include the name of the process responsible for the changes from
your endpoints into the `Endpoint` datamodel in the `Processes` node. In addition,
confirm the latest CIM App 4.20 or higher is installed and the latest TA for the
endpoint product.
known_false_positives: It is possible for this search to generate a notable event
for a batch file write to a path that includes the string "system32", but is not
the actual Windows system directory. As such, you should confirm the path of the
batch file identified by the search. In addition, a false positive may be generated
by an administrator copying a legitimate batch file in this directory tree. You
should confirm that the activity is legitimate and modify the search to add exclusions,
as necessary.
references: []
tags:
analytic_story:
- SamSam Ransomware
asset_type: Endpoint
confidence: 90
impact: 70
message: A file - $file_name$ was written to system32 has occurred on endpoint $dest$
by user $user$.
mitre_attack_id:
- T1204
- T1204.002
observable:
- name: user
type: User
role:
- Victim
- name: dest
type: Hostname
role:
- Victim
- name: file_name
type: File Name
role:
- Victim
product:
- Splunk Enterprise
- Splunk Enterprise Security
- Splunk Cloud
required_fields:
- _time
- Filesystem.dest
- Filesystem.file_create_time
- Filesystem.file_name
- Filesystem.user
- Filesystem.file_path
- Processes.process_name
- Processes.dest
- Filesystem.process_guid
- Processes.process_guid
- Processes.dest
- Processes.process_name
risk_score: 63
security_domain: endpoint
tests:
- name: True Positive Test
attack_data:
- data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1204.002/batch_file_in_system32/windows-sysmon.log
source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
sourcetype: xmlwineventlog