Windows: Execution of Pcalua.exe with -a Argument

Flags Pcalua.exe executions containing " -a" that may indicate indirect command execution on Windows.

FreeReviewedSigma · Medium · v2

Product: windows
Category: process_creation
Author: Nasreddine Bencherchali (Nextron Systems), E.M. Anhaus (originally from Atomic Blue Detections, Endgame), oscd.community (SigmaHQ), DRL 1.1
Published: 2022-06-14
Updated: 2026-07-31

ATT&CK techniques

Execution

Recon
Resource Dev
Initial Access
Execution
- T1059Command and Scripting Interpreter
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule flags process creation where Image ends with \pcalua.exe and the CommandLine contains the substring " -a". Attackers can use Pcalua.exe to invoke indirect command execution behavior, which may help bypass application allowlisting controls. Detection relies on Windows process creation telemetry including the executable path and full command line.

Reporting behind it

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Windows: Execution of Pcalua.exe with -a Argument

Pivot detection · T1059 · 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-pcalua-exe-flag-a-command-execution-0955e4e1

title: "Windows: Execution of Pcalua.exe with -a Argument"
id: a993f35d-7ea6-4af6-b7c4-4f4669e9ed0d
related:
  - id: fa47597e-90e9-41cd-ab72-c3b74cfb0d02
    type: obsolete
  - id: 0955e4e1-c281-4fb9-9ee1-5ee7b4b754d2
    type: derived
status: test
description: This rule flags process creation where Image ends with \pcalua.exe and the CommandLine contains the substring " -a". Attackers can use Pcalua.exe to invoke indirect command execution behavior, which may help bypass application allowlisting controls. Detection relies on Windows process creation telemetry including the executable path and full command line.
references:
  - https://lolbas-project.github.io/lolbas/Binaries/Pcalua/
  - https://pentestlab.blog/2020/07/06/indirect-command-execution/
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_lolbin_pcalua.yml
author: Nasreddine Bencherchali (Nextron Systems), E.M. Anhaus (originally from Atomic Blue Detections, Endgame), oscd.community, Huntrule Team
date: 2022-06-14
modified: 2023-01-04
tags:
  - attack.execution
  - attack.t1059
logsource:
  category: process_creation
  product: windows
detection:
  selection:
    Image|endswith: \pcalua.exe
    CommandLine|contains: " -a"
  condition: selection
falsepositives:
  - Legitimate use by a via a batch script or by an administrator.
level: medium
license: DRL-1.1

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