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Detection rules › Sigma

Cloudflared Tunnel Connections Cleanup

Status
test
Severity
medium
Log source
category process_creation, product windows
Author
Nasreddine Bencherchali (Nextron Systems)
Source
github.com/SigmaHQ/sigma

Detects execution of the "cloudflared" tool with the tunnel "cleanup" flag in order to cleanup tunnel connections.

Known false positives

  • Legitimate usage of Cloudflared.

MITRE ATT&CK coverage

TacticTechniques
Command & Control

Telemetry coverage

ProviderRecord / event type
SysmonEvent ID 1: Process creation
Security-AuditingEvent ID 4688: A new process has been created.

Rule body

title: Cloudflared Tunnel Connections Cleanup
id: 7050bba1-1aed-454e-8f73-3f46f09ce56a
status: test
description: Detects execution of the "cloudflared" tool with the tunnel "cleanup" flag in order to cleanup tunnel connections.
references:
    - https://github.com/cloudflare/cloudflared
    - https://developers.cloudflare.com/cloudflare-one/connections/connect-apps
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-05-17
modified: 2023-12-21
tags:
    - attack.command-and-control
    - attack.t1102
    - attack.t1090
    - attack.t1572
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        CommandLine|contains|all:
            - ' tunnel '
            - 'cleanup '
        CommandLine|contains:
            - '-config '
            - '-connector-id '
    condition: selection
falsepositives:
    - Legitimate usage of Cloudflared.
level: medium

Stages and Predicates

Stage 0: condition

selection

Stage 1: selection

selection:
    CommandLine|contains|all:
        - ' tunnel '
        - 'cleanup '
    CommandLine|contains:
        - '-config '
        - '-connector-id '

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
CommandLinematch
  • tunnel corpus 3 (sigma 3)
  • -config corpus 3 (sigma 3)
  • -connector-id corpus 2 (sigma 2)
  • cleanup corpus 2 (sigma 2)
field:"CommandLine" kind:match