Anomalous usage of Archive Tools
Description
The following detection identifies the usage of archive tools from the command line.
- Type: Anomaly
- Product: Splunk Behavioral Analytics
- Datamodel: Endpoint_Processes
- Last Updated: 2021-11-22
- Author: Patrick Bareiss, Splunk
- ID: 63614a58-10e2-4c6c-ae81-ea1113681439
Annotations
ATT&CK
Kill Chain Phase
- Exploitation
NIST
CIS20
CVE
Search
1
2
3
4
5
6
7
8
| from read_ssa_enriched_events()
| eval timestamp=parse_long(ucast(map_get(input_event,"_time"), "string", null)), process=lower(ucast(map_get(input_event, "process"), "string", null)), process_name=lower(ucast(map_get(input_event, "process_name"), "string", null)), process_path=ucast(map_get(input_event, "process_path"), "string", null), parent_process_name=ucast(map_get(input_event, "parent_process_name"), "string", null), parent_process=ucast(map_get(input_event, "parent_process"), "string", null), event_id=ucast(map_get(input_event, "event_id"), "string", null)
| where process_name IS NOT NULL AND parent_process_name IS NOT NULL
| where like(process_name, "7z%") OR process_name="WinRAR.exe" OR like(process_name, "winzip%")
| where like(parent_process_name, "%cmd.exe") OR like(parent_process_name, "%powershell.exe")
| eval start_time=timestamp, end_time=timestamp, entities=mvappend(ucast(map_get(input_event, "dest_user_id"), "string", null), ucast(map_get(input_event, "dest_device_id"), "string", null)), body=create_map(["event_id", event_id, "process_name", process_name, "parent_process_name", parent_process_name, "process_path", process_path])
| into write_ssa_detected_events();
Macros
The SPL above uses the following Macros:
anomalous_usage_of_archive_tools_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Required fields
List of fields required to use this analytic.
- _time
- Processes.process_name
- Processes.process
- Processes.dest
- Processes.user
- Processes.parent_process_name
- Processes.parent_process
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.
Known False Positives
False positives can be ligitmate usage of archive tools from the command line.
Associated Analytic Story
RBA
Risk Score | Impact | Confidence | Message |
---|---|---|---|
42.0 | 70 | 60 | An instance of $parent_process_name$ spawning $process_name$ was identified on endpoint $dest$ by user $user$. This behavior is indicative of suspicious loading of 7zip. |
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
Reference
Test Dataset
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 | version: 1