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T1055.003 Thread Execution Hijacking

Adversaries may inject malicious code into hijacked processes in order to evade process-based defenses as well as possibly elevate privileges. Thread Execution Hijacking is a method of executing arbitrary code in the address space of a separate live process.

Thread Execution Hijacking is commonly performed by suspending an existing process then unmapping/hollowing its memory, which can then be replaced with malicious code or the path to a DLL. A handle to an existing victim process is first created with native Windows API calls such as OpenThread. At this point the process can be suspended then written to, realigned to the injected code, and resumed via SuspendThread , VirtualAllocEx, WriteProcessMemory, SetThreadContext, then ResumeThread respectively.1

This is very similar to Process Hollowing but targets an existing process rather than creating a process in a suspended state.

Running code in the context of another process may allow access to the process’s memory, system/network resources, and possibly elevated privileges. Execution via Thread Execution Hijacking may also evade detection from security products since the execution is masked under a legitimate process.

Item Value
ID T1055.003
Sub-techniques T1055.001, T1055.002, T1055.003, T1055.004, T1055.005, T1055.008, T1055.009, T1055.011, T1055.012, T1055.013, T1055.014, T1055.015
Tactics TA0005, TA0004
Platforms Windows
Permissions required User
Version 1.1
Created 14 January 2020
Last Modified 18 October 2021

Procedure Examples

ID Name Description
S0168 Gazer Gazer performs thread execution hijacking to inject its orchestrator into a running thread from a remote process.45
S0094 Trojan.Karagany Trojan.Karagany can inject a suspended thread of its own process into a new process and initiate via the ResumeThread API.3
S0579 Waterbear Waterbear can use thread injection to inject shellcode into the process of security software.2


ID Mitigation Description
M1040 Behavior Prevention on Endpoint Some endpoint security solutions can be configured to block some types of process injection based on common sequences of behavior that occur during the injection process.


ID Data Source Data Component
DS0009 Process OS API Execution