Windows whoami.exe Renamed Execution via Mismatched OriginalFileName

ATT&CK techniques

Discovery

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
- T1033System Owner/User Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule flags Windows process creation events where the process metadata still indicates OriginalFileName as whoami.exe, but the executed image path ends with a different filename. Renaming built-in reconnaissance utilities like whoami can help attackers evade name-based detections and blend in with other tools. It relies on Windows process creation telemetry that includes both OriginalFileName and the Image path for the spawned process.

Reporting behind it

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Linux Process Creation: ESXi esxcli system discovery via system namespace

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Windows whoami.exe Renamed Execution via Mismatched OriginalFileName

Pivot detection · T1033 · 9 related

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

windows-whoami-exe-renamed-execution-via-mismatched-originalfilename-f1086bf7

title: Windows whoami.exe Renamed Execution via Mismatched OriginalFileName
id: 5f0ef87f-d7de-4ed9-b13b-e36179de9aab
status: test
description: This rule flags Windows process creation events where the process metadata still indicates OriginalFileName as whoami.exe, but the executed image path ends with a different filename. Renaming built-in reconnaissance utilities like whoami can help attackers evade name-based detections and blend in with other tools. It relies on Windows process creation telemetry that includes both OriginalFileName and the Image path for the spawned process.
references:
  - https://brica.de/alerts/alert/public/1247926/agent-tesla-keylogger-delivered-inside-a-power-iso-daa-archive/
  - https://app.any.run/tasks/7eaba74e-c1ea-400f-9c17-5e30eee89906/
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_renamed_whoami.yml
author: Florian Roth (Nextron Systems), Huntrule Team
date: 2021-08-12
modified: 2022-10-09
tags:
  - attack.discovery
  - attack.t1033
  - car.2016-03-001
logsource:
  category: process_creation
  product: windows
detection:
  selection:
    OriginalFileName: whoami.exe
  filter:
    Image|endswith: \whoami.exe
  condition: selection and not filter
falsepositives:
  - Unknown
level: critical
license: DRL-1.1
related:
  - id: f1086bf7-a0c4-4a37-9102-01e573caf4a0
    type: derived

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