Windows certutil.exe Initiates Network Connections to Common Service Ports

Alerts when certutil.exe initiates outbound network connections to ports 80, 135, 443, or 445 on Windows.

FreeReviewedSigma · High · v2

Product: windows
Category: network_connection
Author: frack113, Florian Roth (Nextron Systems) (SigmaHQ), DRL 1.1
Published: 2022-09-02
Updated: 2026-07-31

ATT&CK techniques

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
- T1105Ingress Tool Transfer
Exfiltration
Impact

What it detects

This rule flags network connections where certutil.exe is the initiating process and the destination port is 80, 135, 443, or 445. Attackers may abuse certutil.exe to retrieve remote content or staging payloads, making process-to-network telemetry important for identifying suspicious command-and-control behavior. It relies on Windows network connection events that include the initiating image path, connection direction, and destination port.

Reporting behind it

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Windows certutil.exe Initiates Network Connections to Common Service Ports

Pivot detection · T1105 · 9 related

Changelog

v2
Candidate ingested via manual entry.2026-07-31
v1
No changelog recorded for this version.2026-07-30

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

windows-certutil-exe-initiating-network-connections-to-common-service-ports-0dba975d

title: Windows certutil.exe Initiates Network Connections to Common Service Ports
id: 95205cda-0700-42f3-9754-395e2cba38d4
status: test
description: This rule flags network connections where certutil.exe is the initiating process and the destination port is 80, 135, 443, or 445. Attackers may abuse certutil.exe to retrieve remote content or staging payloads, making process-to-network telemetry important for identifying suspicious command-and-control behavior. It relies on Windows network connection events that include the initiating image path, connection direction, and destination port.
references:
  - https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/certutil
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/network_connection/net_connection_win_certutil_initiated_connection.yml
author: frack113, Florian Roth (Nextron Systems), Huntrule Team
date: 2022-09-02
modified: 2024-05-31
tags:
  - attack.command-and-control
  - attack.t1105
logsource:
  category: network_connection
  product: windows
detection:
  selection:
    Image|endswith: \certutil.exe
    Initiated: "true"
    DestinationPort:
      - 80
      - 135
      - 443
      - 445
  condition: selection
falsepositives:
  - Unknown
level: high
license: DRL-1.1
related:
  - id: 0dba975d-a193-4ed1-a067-424df57570d1
    type: derived

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