Potential Data Exfiltration via Rclone

[metadata]
creation_date = "2026/03/18"
integration = ["endpoint", "windows", "sentinel_one_cloud_funnel", "m365_defender", "system", "crowdstrike"]
maturity = "production"
updated_date = "2026/03/24"

[rule]
author = ["Elastic"]
description = """
Identifies abuse of rclone (or a renamed copy, e.g. disguised as a security or backup utility) to exfiltrate data to
cloud storage or remote endpoints. Rclone is a legitimate file sync tool; threat actors rename it to blend with
administrative traffic and use copy/sync with cloud backends (e.g. :s3:) and include filters to exfiltrate specific
file types.
"""
from = "now-9m"
index = [
    "endgame-*",
    "logs-crowdstrike.fdr*",
    "logs-endpoint.events.process-*",
    "logs-m365_defender.event-*",
    "logs-sentinel_one_cloud_funnel.*",
    "logs-system.security*",
    "logs-windows.sysmon_operational-*",
    "winlogbeat-*",
]
language = "eql"
license = "Elastic License v2"
name = "Potential Data Exfiltration via Rclone"
note = """## Triage and analysis

### Investigating Potential Data Exfiltration via Rclone

Rclone is a legitimate file synchronization tool. Threat actors abuse it (often renamed, e.g. to TrendFileSecurityCheck.exe) to exfiltrate data to S3, HTTP endpoints, or other cloud backends, using `copy`/`sync` with `--include` filters and high `--transfers` to move specific file types at scale.

### Possible investigation steps

- Confirm the command line for `copy`/`sync`, cloud backend (e.g. `:s3:`, `:http`), and options like `--include`, `--transfers`, `-P`.
- If the process name is not `rclone.exe`, compare with `process.pe.original_file_name`; a mismatch indicates a renamed copy used to evade name-based detection.
- From the command line, identify the source path (e.g. UNC or local) and the remote backend (S3 bucket, HTTP endpoint) as the exfil destination.
- Review `--include`/`--exclude` and `--max-age`/`--max-size` to understand what data was targeted (documents, CAD, archives, etc.).
- Correlate with the process executable path (recently dropped?), parent process, and user; look for outbound network to the same backend.

### False positive analysis

- Legitimate backup or sync jobs using rclone from a known path and config may trigger; allowlist by process path or `--config` path for approved rclone usage.

### Response and remediation

- Terminate the rclone process and isolate the host if exfiltration is confirmed.
- Identify and revoke access to the destination (S3 bucket, API keys, etc.); preserve logs for the exfil session.
- Determine scope of data exposed and notify stakeholders; rotate credentials and secrets that may have been in exfiltrated paths.
"""
references = [
    "https://attack.mitre.org/techniques/T1048/",
    "https://rclone.org/commands/rclone_copy/",
]
risk_score = 47
rule_id = "3f4c2b18-9d2e-4b7a-a3c1-8e6d9f2b5c7e"
severity = "medium"
tags = [
    "Domain: Endpoint",
    "OS: Windows",
    "Use Case: Threat Detection",
    "Tactic: Exfiltration",
    "Resources: Investigation Guide",
    "Data Source: Elastic Defend",
    "Data Source: Sysmon",
    "Data Source: SentinelOne",
    "Data Source: Microsoft Defender for Endpoint",
    "Data Source: Crowdstrike",
    "Data Source: Elastic Endgame", 
    "Data Source: Windows Security Event Logs"
]
timestamp_override = "event.ingested"
type = "eql"

query = '''
process where host.os.type == "windows" and event.type == "start" and
 (process.name : "rclone.exe" or ?process.pe.original_file_name == "rclone.exe") and process.args : ("copy", "sync") and
  not process.args : ("--config=?:\\Program Files\\rclone\\config\\rclone\\rclone.conf", "--config=?:\\Program Files (x86)\\rclone\\config\\rclone\\rclone.conf") and 
  not process.executable : ("?:\\Program Files*", "\\Device\\HarddiskVolume*\\Program Files*")
'''


[[rule.threat]]
framework = "MITRE ATT&CK"

[[rule.threat.technique]]
id = "T1048"
name = "Exfiltration Over Alternative Protocol"
reference = "https://attack.mitre.org/techniques/T1048/"

[[rule.threat.technique]]
id = "T1567"
name = "Exfiltration Over Web Service"
reference = "https://attack.mitre.org/techniques/T1567/"

[[rule.threat.technique.subtechnique]]
id = "T1567.002"
name = "Exfiltration to Cloud Storage"
reference = "https://attack.mitre.org/techniques/T1567/002/"

[rule.threat.tactic]
id = "TA0010"
name = "Exfiltration"
reference = "https://attack.mitre.org/tactics/TA0010/"

[[rule.threat]]
framework = "MITRE ATT&CK"

[[rule.threat.technique]]
id = "T1036"
name = "Masquerading"
reference = "https://attack.mitre.org/techniques/T1036/"

[[rule.threat.technique.subtechnique]]
id = "T1036.003"
name = "Rename Legitimate Utilities"
reference = "https://attack.mitre.org/techniques/T1036/003/"

[rule.threat.tactic]
id = "TA0005"
name = "Defense Evasion"
reference = "https://attack.mitre.org/tactics/TA0005/"