Windows Process Creation: Suspicious CHCP Code Page Switch to Rare Locale

Alerts on suspicious chcp.com usage that switches Windows code pages to specific rare identifiers in process creation logs.

FreeReviewedSigma · Medium · v2

Product: windows
Category: process_creation
Author: Florian Roth (Nextron Systems), Jonhnathan Ribeiro, oscd.community (SigmaHQ), DRL 1.1
Published: 2019-10-14
Updated: 2026-07-31

Analysis Detection

ATT&CK techniques

Defense Evasion

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
- T1036Masquerading
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

Identifies process executions of chcp.com where the command line ends with code pages 936 or 1258, which are less commonly used in typical environments. Attackers may switch console/code-page settings to alter text encoding and hinder analysis of terminal output or scripted content. The detection relies on Windows process creation telemetry, specifically the image name ending with \chcp.com and command-line arguments containing the selected code page identifiers.

Reporting behind it

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Windows Process Creation: Suspicious CHCP Code Page Switch to Rare Locale

Pivot detection · T1036 · 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-chcp-code-page-switch-via-chcp-com-in-command-line-bat-c7942406

title: "Windows Process Creation: Suspicious CHCP Code Page Switch to Rare Locale"
id: a4287a7f-e7f0-41c8-ad29-8271d35ab68c
status: test
description: Identifies process executions of chcp.com where the command line ends with code pages 936 or 1258, which are less commonly used in typical environments. Attackers may switch console/code-page settings to alter text encoding and hinder analysis of terminal output or scripted content. The detection relies on Windows process creation telemetry, specifically the image name ending with \chcp.com and command-line arguments containing the selected code page identifiers.
references:
  - https://learn.microsoft.com/en-us/windows/win32/intl/code-page-identifiers
  - https://twitter.com/cglyer/status/1183756892952248325
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_chcp_codepage_switch.yml
author: Florian Roth (Nextron Systems), Jonhnathan Ribeiro, oscd.community, Huntrule Team
date: 2019-10-14
modified: 2023-03-07
tags:
  - attack.stealth
  - attack.t1036
logsource:
  category: process_creation
  product: windows
detection:
  selection:
    Image|endswith: \chcp.com
    CommandLine|endswith:
      - " 936"
      - " 1258"
  condition: selection
falsepositives:
  - Administrative activity (adjust code pages according to your organization's region)
level: medium
regression_tests_path: regression_data/rules/windows/process_creation/proc_creation_win_chcp_codepage_switch/info.yml
license: DRL-1.1
related:
  - id: c7942406-33dd-4377-a564-0f62db0593a3
    type: derived

Convert

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