Detection: Cisco NVM - Rclone Execution With Network Activity

Updated Date: 2025-07-03 ID: 719f8c78-b20d-4bb9-8c33-6d1a762e7a9a Author: Nasreddine Bencherchali, Splunk Type: Anomaly Product: Splunk Enterprise Security

Description

This detection identifies execution of the file synchronization utility "rclone". It leverages Cisco Network Visibility Module logs, specifically flow data in order to capture process executions initiating network connections. While rclone is a legitimate command-line tool for syncing data to cloud storage providers, it has been widely abused by threat actors for data exfiltration. This analytic inspects process name and arguments for rclone and flags usage of suspicious flags. If matched, this could indicate malicious usage for stealthy data exfiltration or cloud abuse.

Search

 1`cisco_network_visibility_module_flowdata`
 2(
 3  process_name = "rclone.exe"
 4  OR
 5  (
 6    process_arguments = "* copy *"
 7    process_arguments = "*\\\\*"
 8    process_arguments IN ("*remote:*", "*mega:*", "*ftp:*", "*ftp1:*")
 9  )
10  OR
11  (
12    process_arguments IN ("*remote:*", "*mega:*", "*ftp:*", "*ftp1:*")
13    process_arguments = "*--transfers"
14    process_arguments = "*--ignore-existing*"
15    process_arguments = "*--auto-confirm*"
16  )
17)
18
19| stats count min(_time) as firstTime max(_time) as lastTime
20        values(parent_process_arguments) as parent_process_arguments
21        values(process_arguments) as process_arguments
22        values(parent_process_hash) as parent_process_hash
23        values(process_hash) as process_hash
24        values(module_name_list) as module_name_list
25        values(module_hash_list) as module_hash_list
26        values(dest_port) as dest_port
27        values(aliul) as additional_logged_in_users_list
28        values(dest_hostname) as dest_hostname
29        by src dest parent_process_path parent_process_integrity_level process_path process_name process_integrity_level process_id transport
30
31| `security_content_ctime(firstTime)`
32
33| `security_content_ctime(lastTime)`
34
35| table
36  parent_process_integrity_level parent_process_path parent_process_arguments parent_process_hash
37  process_integrity_level process_path process_name process_arguments process_hash process_id
38  additional_logged_in_users_list module_name_list module_hash_list
39  src dest_hostname dest dest_port transport firstTime lastTime
40
41| `cisco_nvm___rclone_execution_with_network_activity_filter`

Data Source

Name	Platform	Sourcetype	Source
Cisco Network Visibility Module Flow Data	Network	`'cisco:nvm:flowdata'`	`'not_applicable'`

Macros Used

Name	Value
cisco_network_visibility_module_flowdata	`sourcetype="cisco:nvm:flowdata"`
cisco_nvm___rclone_execution_with_network_activity_filter	`search *`

cisco_nvm___rclone_execution_with_network_activity_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK

+ Kill Chain Phases

+ NIST

+ CIS

- Threat Actors

ID	Technique	Tactic
T1567.002	Exfiltration to Cloud Storage	Exfiltration

Actions on Objectives

DE.AE

CIS 10

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Setting	Value
Disabled	true
Cron Schedule	`0 * * * *`
Earliest Time	`-70m@m`
Latest Time	`-10m@m`
Schedule Window	`auto`
Creates Risk Event	True

This configuration file applies to all detections of type anomaly. These detections will use Risk Based Alerting.

Implementation

This search requires Network Visibility Module logs, which includes the flow data sourcetype. This search uses an input macro named cisco_network_visibility_module_flowdata. We strongly recommend that you specify your environment-specific configurations (index, source, sourcetype, etc.) for Cisco Network Visibility Module logs. Replace the macro definition with configurations for your Splunk environment. The search also uses a post-filter macro designed to filter out known false positives. The logs are to be ingested using the Splunk Add-on for Cisco Endpoint Security Analytics (CESA) (https://splunkbase.splunk.com/app/4221).

Known False Positives

Rclone is used legitimately in some backup or other workflows. Tune this rule based on known-good operational usage or restrict by known user/service accounts an specific folders or remote names.

Associated Analytic Story

Cisco Network Visibility Module Analytics

Risk Based Analytics (RBA)

Risk Message:

Rclone was executed on $src$ using flags $process_arguments$ and connected to $dest_hostname$ over $dest_port$.

Risk Object	Risk Object Type	Risk Score	Threat Objects
src	system	60	process_name

References

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	✅ Passing	N/A	N/A	N/A
Unit	✅ Passing	Dataset	`not_applicable`	`cisco:nvm:flowdata`
Integration	✅ Passing	Dataset	`not_applicable`	`cisco:nvm:flowdata`

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: GitHub | Version: 1