HackTool - HollowReaper Execution

Hunt Hypothesis

Detects usage of HollowReaper, a process hollowing shellcode launcher used for stealth payload execution through process hollowing. It replaces the memory of a legitimate process with custom shellcode

Detection Rule

Sigma (Original)

title: HackTool - HollowReaper Execution
id: 85d23b42-9a9d-4f8f-b3d7-d2733c1d58f5
status: experimental
description: |
    Detects usage of HollowReaper, a process hollowing shellcode launcher used for stealth payload execution through process hollowing.
    It replaces the memory of a legitimate process with custom shellcode, allowing the attacker to execute payloads under the guise of trusted binaries.
references:
    - https://github.com/vari-sh/RedTeamGrimoire/tree/b5e7635d34db6e1f0398d8847e8f293186e947c5/HollowReaper
author: Swachchhanda Shrawan Poudel (Nextron Systems)
date: 2025-07-01
tags:
    - attack.privilege-escalation
    - attack.stealth
    - attack.t1055.012
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: '\HollowReaper.exe'
    condition: selection
falsepositives:
    - Unknown
level: high

KQL (Azure Sentinel)

imProcessCreate
| where TargetProcessName endswith "\\HollowReaper.exe"

Required Data Sources

False Positive Guidance

• Unknown

MITRE ATT&CK Context

• Tactic: Privilege Escalation
• Technique: T1055.012 — T1055.012

References

• https://github.com/vari-sh/RedTeamGrimoire/tree/b5e7635d34db6e1f0398d8847e8f293186e947c5/HollowReaper
• SigmaHQ Rule