Cloudflared Portable Execution — Sigma Rule

Rule metadata and linked tags

Author: Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: medium. Source dates: 2023-12-20 / not supplied.

{
  "category": "process_creation",
  "product": "windows"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: a9873bcefc17ed42e0eeb4c1cb05d1c1cb1aa2da90eed3a9cf010c9e2523ddea

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Cloudflared Portable Execution
id: fadb84f0-4e84-4f6d-a1ce-9ef2bffb6ccd
status: test
description: |
    Detects the execution of the "cloudflared" binary from a non standard location.
references:
    - https://developers.cloudflare.com/cloudflare-one/connections/connect-networks/do-more-with-tunnels/trycloudflare/
    - https://github.com/cloudflare/cloudflared
    - https://www.intrinsec.com/akira_ransomware/
    - https://www.guidepointsecurity.com/blog/tunnel-vision-cloudflared-abused-in-the-wild/
    - https://github.com/cloudflare/cloudflared/releases
author: Nasreddine Bencherchali (Nextron Systems)
tags:
    - attack.command-and-control
    - attack.t1090.001
date: 2023-12-20
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: '\cloudflared.exe'
    filter_main_admin_location:
        Image|contains:
            - ':\Program Files (x86)\cloudflared\'
            - ':\Program Files\cloudflared\'
    condition: selection and not 1 of filter_main_*
falsepositives:
    - Legitimate usage of Cloudflared portable versions
level: medium

Original YAML and metadata in JSON

False positives

• Legitimate usage of Cloudflared portable versions

Source references

• https://developers.cloudflare.com/cloudflare-one/connections/connect-networks/do-more-with-tunnels/trycloudflare/
• https://github.com/cloudflare/cloudflared
• https://www.intrinsec.com/akira_ransomware/
• https://www.guidepointsecurity.com/blog/tunnel-vision-cloudflared-abused-in-the-wild/
• https://github.com/cloudflare/cloudflared/releases