ID	E1055
Objective(s)	Defense Evasion, Privilege Escalation
Related ATT&CK Techniques	Process Injection (T1055, T1631)
Version	2.0
Created	1 August 2019
Last Modified	13 September 2023

Process Injection

Malware may execute code in the address space of a separate process.

See ATT&CK: Process Injection (T1055, T1631).

The methods table includes existing ATT&CK sub-techniques, which have been enhanced with malware-specific details, as well as new methods. Note that IAT hooking and inline hooking (aka userland rootkits) are defined as methods under the Hijack Execution Flow behavior.

Methods

Name	ID	Description
Dynamic-link Library Injection	E1055.001	(Enhanced ATT&CK sub-technique) Malware creates a thread using CreateRemoteThread (or NtCreateThreadEx, RtlCreateUserThread) and LoadLibrary. The path to the malware's malicious dynamic-link library (DLL) is written in the virtual address space of another process; the malware ensures the remote process loads it by creating a remote thread in the target process. This is one of the most common process injection methods, called Classic DLL Injection via CreateRemoteThread and LoadLibrary in [1]. This method is related to Unprotect technique U1226.
Portable Executable Injection	E1055.002	(Enhanced ATT&CK sub-technique) Malware copies its malicious code into an existing open process and causes it to execute via shellcode or by calling CreateRemoteThread (instead of passing the address of the LoadLibrary), called Portable Executable Injection in [1]. This method is related to Unprotect technique U1216.
Thread Execution Hijacking	E1055.003	(Enhanced ATT&CK sub-technique) Malware targets an existing thread of a process, avoiding noisy process or thread creations operations, called Thread Execution Hijacking in [1]. This method is related to Unprotect technique U1223.
Asynchronous Procedure Call	E1055.004	(Enhanced ATT&CK sub-technique) Malware may leverage Asynchronous Procedure Calls (APC) to force another thread to execute its code by attaching it to the APC Queue of the target thread (using QueueUserAPC / NtQueueApcThread). AtomBombing [1][3], a variant of APC injection, occurs when the attacker stores malicious code in the global atom table. The APC gets the targeted process to retrieve the code that will be injected to the memory of the targeted process. This method is related to Unprotect technique U1221 and U1220.
Extra Window Memory Injection	E1055.011	(Enhanced ATT&CK sub-technique) Malware may inject into Explorer tray window’s extra window memory, called Extra Window Memory Injection in [1]. This method is related to Unprotect technique U1219.
Process Hollowing	E1055.012	(Enhanced ATT&CK sub-technique) Instead of injecting code into a program, malware can upmap (hollow out) legitimate code from memory of a target process, overwriting it with a malicious executable, called Process Hollowing in [1]. This method is related to Unprotect technique U1225.
Hook Injection via SetWindowsHooksEx	E1055.m01	Malware can leverage hooking functionality to have its malicious DLL loaded upon an event getting triggered in a specific thread, which is usually done by calling SetWindowsHookEx to install a hook routine into the hook chain. [1] This method is related to Unprotect technique 1227.
Injection and Persistence via Registry Modification	E1055.m02	Malware may insert the location of its malicious library under a registry key (e.g., Appinit_DLL, AppCertDlls, IFEO) to have another process load its library. [1]
Injection via Windows Fibers	E1055.m05	Malware executes shellcode via Windows fibers by converting a thread to a fiber. [5]
Injection using Shims	E1055.m03	Malware may use shims to target an executable (shims are a way of hooking into APIs and targeting specific executables and are provided by Microsoft for backward compatibility, allowing developers to apply program fixes without rewriting code). [1] This method is related to Unprotect technique U1218.
Patch Process Command Line	E1055.m04	Malware patches the PEB of a process to spoof the arguments.

Use in Malware

Name	Date	Method	Description
UP007	2016	E1055.001	The malware loads multiple DLLs into memory. [4]
TrickBot	2016	--	The malware injects itself into svchost.exe. [11]
Poison Ivy	2005	--	Poison Ivy code is injected into explorer.exe. [2]
WebCobra	2018	--	The malware injects miner code into a running process. [12]
CryptoWall	2014	--	The malware injects code into a new svchost process. [6]
Hupigon	2013	--	The malware injects itself into processes such as cmd.exe and notepad.exe [7]
Hupigon	2013	E1055.012	The malware uses process replacement. [13]
BlackEnergy	2007	E1055.m05	BlackEnergy bypasses UAC using a Shim Database instructing SndVol.exe to execute cmd.exe instead, allowing for elevated execution. [8]
BlackEnergy	2007	--	BlackEnergy injects its dll component into svchost.exe. [8]
Stuxnet	2010	E1055.001	Stuxnet injects the entire DLL into another process and then just calls the particular export. [9]
Stuxnet	2010	E1055.m02	Stuxnet uses Mrxcls.sys driver for persistence. It is registered as a boot start service by creating the registry key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MRxCIs"ImagePath" = "%System%\drivers\mrxcls.sys". [9]
Netwalker	2020	E1055.001	Netwalker uses reflective DLL loading to inject from memory. [10]
DNSChanger	2011	--	The malware can attach user process memory. [13]
Redhip	2011	E1055.003	The malware can inject threads. [13]
Conti	2019	E1055.012	Conti creates a process in a suspended state and unmaps or removes the PE image layout from a given process space.

Detection

Tool: capa	Mapping	APIs
patch process command line	Process Injection::Patch Process Command Line (E1055.m04)	VirtualProtect, GetProcAddress, ReadProcessMemory
attach user process memory	Process Injection (E1055)	ntoskrnl.KeStackAttachProcess, ntoskrnl.KeUnstackDetachProcess
inject shellcode using extra window memory	Process Injection (E1055)	SetWindowLong, SetWindowLongPtr, PostMessage, SendNotifyMessage
inject shellcode using a file mapping object	Process Injection (E1055)	CreateFileMapping, MapViewOfFile, MapViewOfFileNuma2
inject shellcode using window subclass procedure	Process Injection (E1055)	user32.SetProp, PostMessage, SendNotifyMessage
execute shellcode via Windows fibers	Process Injection::Injection via Windows Fibers (E1055.m05)	ConvertThreadToFiber, CreateFiber, SwitchToFiber