Windows Curl Download to Suspicious Path
Description
The following analytic identifies the use of Windows Curl.exe downloading a file to a suspicious location.
-O or –output is used when a file is to be downloaded and placed in a specified location.
During triage, review parallel processes for further behavior. In addition, identify if the download was successful. If a file was downloaded, capture and analyze.
- Type: TTP
- Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Datamodel: Endpoint
- Last Updated: 2021-10-19
- Author: Michael Haag, Splunk
- ID: c32f091e-30db-11ec-8738-acde48001122
Annotations
Kill Chain Phase
- Command and Control
NIST
- DE.CM
CIS20
- CIS 10
CVE
Search
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| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where `process_curl` Processes.process IN ("*-O *","*--output*") Processes.process IN ("*\\appdata\\*","*\\programdata\\*","*\\public\\*") by Processes.dest Processes.user Processes.parent_process_name Processes.process_name Processes.original_file_name Processes.process Processes.process_id Processes.parent_process_id
| `drop_dm_object_name(Processes)`
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `windows_curl_download_to_suspicious_path_filter`
Macros
The SPL above uses the following Macros:
windows_curl_download_to_suspicious_path_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.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. 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 Administrators or super users will use Curl for legitimate purposes. Filter as needed.
Associated Analytic Story
RBA
Risk Score | Impact | Confidence | Message |
---|---|---|---|
80.0 | 80 | 100 | An instance of $parent_process_name$ spawning $process_name$ was identified on endpoint $dest$ by user $user$ to download a file to a suspicious directory. |
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
- https://thedfirreport.com/2021/10/18/icedid-to-xinglocker-ransomware-in-24-hours/
- https://attack.mitre.org/techniques/T1105/
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1105/T1105.md
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