---
title: "Clear Unallocated Sector Using Cipher App"
excerpt: "File Deletion, Indicator Removal on Host"
categories:
  - Endpoint
last_modified_at: 2021-12-20
toc: true
toc_label: ""
tags:
  - File Deletion
  - Defense Evasion
  - Indicator Removal on Host
  - Defense Evasion
  - Splunk Behavioral Analytics
  - Endpoint_Processes
---



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#### Description

this search is to detect execution of `cipher.exe` to clear the unallocated sectors of a specific disk. This technique was seen in some ransomware to make it impossible to forensically recover deleted files.

- **Type**: [TTP](https://github.com/splunk/security_content/wiki/Detection-Analytic-Types)
- **Product**: Splunk Behavioral Analytics
- **Datamodel**: [Endpoint_Processes](https://docs.splunk.com/Documentation/CIM/latest/User/EndpointProcesses)
- **Last Updated**: 2021-12-20
- **Author**: Teoderick Contreras, Splunk
- **ID**: 8f907d90-6173-11ec-9c23-acde48001122


#### [ATT&CK](https://attack.mitre.org/)

| ID             | Technique        |  Tactic             |
| -------------- | ---------------- |-------------------- |
| [T1070.004](https://attack.mitre.org/techniques/T1070/004/) | File Deletion | Defense Evasion |

| [T1070](https://attack.mitre.org/techniques/T1070/) | Indicator Removal on Host | Defense Evasion |

#### Search

```

| from read_ssa_enriched_events() 
| eval timestamp=parse_long(ucast(map_get(input_event, "_time"), "string", null)), cmd_line=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), event_id=ucast(map_get(input_event, "event_id"), "string", null) 
| where cmd_line IS NOT NULL AND like(cmd_line, "%/w:%") AND process_name="cipher.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, "cmd_line", cmd_line, "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:

Note that `clear_unallocated_sector_using_cipher_app_filter` is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

#### Required field
* _time
* Processes.dest
* Processes.user
* Processes.parent_process_name
* Processes.parent_process
* Processes.original_file_name
* Processes.process_name
* Processes.process
* Processes.process_id
* Processes.parent_process_path
* Processes.process_path
* Processes.parent_process_id


#### 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
administrator may execute this app to manage disk

#### Associated Analytic story
* [Ransomware](/stories/ransomware)
* [Information Sabotage](/stories/information_sabotage)


#### Kill Chain Phase
* Exploitation



#### RBA

| Risk Score  | Impact      | Confidence   | Message      |
| ----------- | ----------- |--------------|--------------|
| 90.0 | 90 | 100 | An instance of $parent_process_name$ spawning $process_name$ was identified on endpoint $dest$ by user $user$ attempting to clear the unallocated sectors of a specific disk. |


Note that risk score is calculated base on the following formula: `(Impact * Confidence)/100`



#### Reference

* [https://unit42.paloaltonetworks.com/vatet-pyxie-defray777/3/](https://unit42.paloaltonetworks.com/vatet-pyxie-defray777/3/)
* [https://www.sophos.com/en-us/medialibrary/PDFs/technical-papers/sophoslabs-ransomware-behavior-report.pdf](https://www.sophos.com/en-us/medialibrary/PDFs/technical-papers/sophoslabs-ransomware-behavior-report.pdf)



#### Test Dataset
Replay any dataset to Splunk Enterprise by using our [`replay.py`](https://github.com/splunk/attack_data#using-replaypy) tool or the [UI](https://github.com/splunk/attack_data#using-ui).
Alternatively you can replay a dataset into a [Splunk Attack Range](https://github.com/splunk/attack_range#replay-dumps-into-attack-range-splunk-server)

* [https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1070.004/cipher/security.log](https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1070.004/cipher/security.log)



[*source*](https://github.com/splunk/security_content/tree/develop/detections/endpoint/clear_unallocated_sector_using_cipher_app.yml) \| *version*: **1**