Windows: PUA - Rclone Execution

Rule ID

PH_Rule_SIGMA_1614

Default Status

Enabled

Description

Detects execution of RClone utility for exfiltration as used by various ransomwares strains like REvil, Conti, FiveHands, etc. This rule is adapted from https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_pua_rclone_execution.yml

Severity

MITRE ATT&CK® Tactics

Exfiltration

Exfiltration consists of techniques that adversaries may use to steal data from your network. Once they’ve collected data, adversaries often package it to avoid detection while removing it. This can include compression and encryption. Techniques for getting data out of a target network typically include transferring it over their command and control channel or an alternate channel and may also include putting size limits on the transmission.

https://attack.mitre.org/tactics/TA0010

MITRE ATT&CK® Techniques

T1567.002

Exfiltration Over Web Service: Exfiltration to Cloud Storage

Adversaries may exfiltrate data to a cloud storage service rather than over their primary command and control channel. Cloud storage services allow for the storage, edit, and retrieval of data from a remote cloud storage server over the Internet.

https://attack.mitre.org/techniques/T1567/002

Impacts

Server

Data Source

Windows Sysmon via FortiSIEM Agent

Detection

Correlation

Remediation Guidance

No remediation guidance specified

Time Window

If the following pattern or patterns match an ingested event within the given time window in seconds, trigger an incident.

300 seconds

Trigger Conditions

If the following defined pattern/s occur within a 300 second time window.

Filter

SubPattern Definitions

SubPattern Name: Filter

This is the named definition of the event query, this is important if multiple subpatterns are defined to distinguish them.

SubPattern Query

This is the query logic that matches incoming events

eventType="Win-Sysmon-1-Create-Process" AND ((command REGEXP ".*--config .*" AND command REGEXP ".*--no-check-certificate .*" AND command REGEXP ".* copy .*") OR ((procName REGEXP "\\rclone\.exe$" OR description="Rsync for cloud storage") AND command REGEXP ".*auto-confirm.*|.*config.*|.*copy.*|.*ftp.*|.*ignore-existing.*|.*ls.*|.*lsd.*|.*mega.*|.*multi-thread-streams.*|.*no-check-certificate .*|.*pass.*|.*pcloud.*|.*remote.*|.*sync.*|.*transfers.*|.*user.*"))

Group by Attributes

This defines how matching events are aggregated, only events with the same matching attribute values are grouped into one unique incident ID

command,description,hostName,procName

Aggregate Constraint

This is most typically a numerical constraint that defines when the rule should trigger an incident

COUNT(*) >= 1

Incident Attribute Mapping

This section defines which fields in matching raw events should be mapped to the incident attributes in the resulting incident.

The available raw event attributes to map are limited to the group by attributes and the aggregate event constraint fields for each subpattern

command = Filter.command,
description = Filter.description,
hostName = Filter.hostName,
procName = Filter.procName

FortiSIEM Rules