t1055-012-process-hollowing

name	T1055.012_process-hollowing
description	Adversaries may inject malicious code into suspended and hollowed processes in order to evade process-based defenses.
category	configuration
version	18.1
author	cyberstrike-official
tags	["mitre-attack","enterprise","t1055.012","defense-evasion","privilege-escalation","windows","sub-technique"]
technique_id	T1055.012
tactic	defense-evasion
all_tactics	["defense-evasion","privilege-escalation"]
platforms	["Windows"]
mitre_url	https://attack.mitre.org/techniques/T1055/012
tech_stack	["windows"]
cwe_ids	["CWE-693"]
chains_with	["T1055","T1055.001","T1055.002","T1055.003","T1055.004","T1055.005","T1055.008","T1055.009","T1055.011","T1055.013","T1055.014","T1055.015"]
prerequisites	["T1055"]
severity_boost	{"T1055":"Chain with T1055 for deeper attack path","T1055.001":"Chain with T1055.001 for deeper attack path","T1055.002":"Chain with T1055.002 for deeper attack path"}

T1055.012 Process Hollowing

Sub-technique of: T1055

High-Level Description

Adversaries may inject malicious code into suspended and hollowed processes in order to evade process-based defenses. Process hollowing is a method of executing arbitrary code in the address space of a separate live process.

Process hollowing is commonly performed by creating a process in a suspended state then unmapping/hollowing its memory, which can then be replaced with malicious code. A victim process can be created with native Windows API calls such as CreateProcess, which includes a flag to suspend the processes primary thread. At this point the process can be unmapped using APIs calls such as ZwUnmapViewOfSection or NtUnmapViewOfSection before being written to, realigned to the injected code, and resumed via VirtualAllocEx, WriteProcessMemory, SetThreadContext, then ResumeThread respectively.

This is very similar to Thread Local Storage but creates a new process rather than targeting an existing process. This behavior will likely not result in elevated privileges since the injected process was spawned from (and thus inherits the security context) of the injecting process. However, execution via process hollowing may also evade detection from security products since the execution is masked under a legitimate process.

Kill Chain Phase

• Defense Evasion (TA0005)
• Privilege Escalation (TA0004)

Platforms: Windows

What to Check

• Identify if Process Hollowing technique is applicable to target environment
• Check Windows systems for indicators of Process Hollowing
• Verify mitigations are bypassed or absent (1 known mitigations)
• Assess detection coverage (1 detection strategies)

How to Test

Atomic Red Team Tests

The following tests are from Atomic Red Team and provide actionable ways to test this technique:

Atomic Test 1: Process Hollowing using PowerShell

This test uses PowerShell to create a Hollow from a PE on disk with explorer as the parent. Credit to FuzzySecurity (https://github.com/FuzzySecurity/PowerShell-Suite/blob/master/Start-Hollow.ps1)