Template -- PowerShell Encoded Command Execution

SIGMA detection rule by WinstonRedGuard -- sigma plugin canonical templates · MIT

Canonical sigma detection template for MITRE ATT&CK T1059.001 (PowerShell Encoded Command Execution). Synthetic exemplar from the WinstonRedGuard threat-intel corpus -- no actor binding; review and bind to your environment before deployment.

title: Template -- PowerShell Encoded Command Execution
id: 43e1c806-e80d-5489-bc06-3620cb6bf257
status: experimental
description: Canonical sigma detection template for MITRE ATT&CK T1059.001 (PowerShell Encoded Command Execution). Synthetic
  exemplar from the WinstonRedGuard threat-intel corpus -- no actor binding; review and bind to your environment before deployment.
references:
- https://attack.mitre.org/techniques/T1059/001/
author: WinstonRedGuard -- sigma plugin canonical templates
date: '2026-05-21'
logsource:
  category: process_creation
  product: windows
detection:
  selection_pwsh_encoded:
    Image|endswith: \powershell.exe
    CommandLine|contains:
    - ' -enc '
    - ' -EncodedCommand '
    - ' -e '
  # Filter added to match observed_alphv_t1059_001.
  # Legit SCCM / installer / management-context
  # PowerShell uses the `-NoProfile -EncodedCommand <short payload>`
  # combination for system-context execution; the selection_*
  # block above previously fired on this benign pattern (prior
  # false-positive finding). Same tradeoff as the T1027 template: adversaries
  # appending `-NoProfile` to bare encoded PS would evade this filter;
  # an entropy / length qualifier on the payload would narrow that
  # gap (the T1027 template has the long_base64_blob selection; this
  # template does not, so the filter is the primary tradeoff knob).
  filter_legit_sccm_installer_encoded_ps:
    CommandLine|contains: ' -NoProfile -EncodedCommand '
  condition: selection_pwsh_encoded and not filter_legit_sccm_installer_encoded_ps
falsepositives:
- Configuration-management and deployment tooling (SCCM, Intune, GPO startup scripts), which routinely invokes PowerShell with -EncodedCommand
- Scheduled administrative jobs that encode their command line to survive quoting
level: medium
tags:
- attack.t1059.001
- wrg.template
- wrg.tactic.execution

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

804bfc63-dc6e-49f8-bdd7-867d870c3d4e

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Executable code, not a declarative rule

This submission is arbitrary [[ currentRule.format ? currentRule.format.toUpperCase() : '' ]] code, not a declarative detection rule — review it as you would any script before running it, and note that it cannot be safely aggregated or auto-executed alongside YARA/Sigma/Suricata/CRS rules.

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Format & documentation suggestions

Not a security issue — this rule is valid and was accepted as-is. These are optional fields/conventions its own format recommends, mainly affecting its quality score and how well it documents itself for other reviewers.

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