type: attack-pattern
spec_version: 2.1
id: attack-pattern--52f3d5a6-8a0f-4f82-977e-750abf90d0b0
created: 2018-01-16T16:13:52.465Z
created_by_ref: identity--c78cb6e5-0c4b-4611-8297-d1b8b55e40b5
revoked: yes
external_references: source_name: mitre-attack
url: https://attack.mitre.org/techniques/T1181
external_id: T1181
source_name: Microsoft Window Classes
description: Microsoft. (n.d.). About Window Classes. Retrieved December 16, 2017.
url: https://msdn.microsoft.com/library/windows/desktop/ms633574.aspx
source_name: Microsoft GetWindowLong function
description: Microsoft. (n.d.). GetWindowLong function. Retrieved December 16, 2017.
url: https://msdn.microsoft.com/library/windows/desktop/ms633584.aspx
source_name: Microsoft SetWindowLong function
description: Microsoft. (n.d.). SetWindowLong function. Retrieved December 16, 2017.
url: https://msdn.microsoft.com/library/windows/desktop/ms633591.aspx
source_name: Elastic Process Injection July 2017
description: Hosseini, A. (2017, July 18). Ten Process Injection Techniques: A Technical Survey Of Common And Trending Process Injection Techniques. Retrieved December 7, 2017.
url: https://www.endgame.com/blog/technical-blog/ten-process-injection-techniques-technical-survey-common-and-trending-process
source_name: MalwareTech Power Loader Aug 2013
description: MalwareTech. (2013, August 13). PowerLoader Injection – Something truly amazing. Retrieved December 16, 2017.
url: https://www.malwaretech.com/2013/08/powerloader-injection-something-truly.html
source_name: WeLiveSecurity Gapz and Redyms Mar 2013
description: Matrosov, A. (2013, March 19). Gapz and Redyms droppers based on Power Loader code. Retrieved December 16, 2017.
url: https://www.welivesecurity.com/2013/03/19/gapz-and-redyms-droppers-based-on-power-loader-code/
source_name: Microsoft SendNotifyMessage function
description: Microsoft. (n.d.). SendNotifyMessage function. Retrieved December 16, 2017.
url: https://msdn.microsoft.com/library/windows/desktop/ms644953.aspx
object_marking_refs: marking-definition--fa42a846-8d90-4e51-bc29-71d5b4802168
modified: 2025-10-24T17:48:47.575Z
name: Extra Window Memory Injection
description: Before creating a window, graphical Windows-based processes must prescribe to or register a windows class, which stipulate appearance and behavior (via windows procedures, which are functions that handle input/output of data). (Citation: Microsoft Window Classes) Registration of new windows classes can include a request for up to 40 bytes of extra window memory (EWM) to be appended to the allocated memory of each instance of that class. This EWM is intended to store data specific to that window and has specific application programming interface (API) functions to set and get its value. (Citation: Microsoft GetWindowLong function) (Citation: Microsoft SetWindowLong function)

Although small, the EWM is large enough to store a 32-bit pointer and is often used to point to a windows procedure. Malware may possibly utilize this memory location in part of an attack chain that includes writing code to shared sections of the process’s memory, placing a pointer to the code in EWM, then invoking execution by returning execution control to the address in the process’s EWM.

Execution granted through EWM injection may take place in the address space of a separate live process. Similar to [Process Injection](https://attack.mitre.org/techniques/T1055), this may allow access to both the target process's memory and possibly elevated privileges. Writing payloads to shared sections also avoids the use of highly monitored API calls such as WriteProcessMemory and CreateRemoteThread. (Citation: Elastic Process Injection July 2017) More sophisticated malware samples may also potentially bypass protection mechanisms such as data execution prevention (DEP) by triggering a combination of windows procedures and other system functions that will rewrite the malicious payload inside an executable portion of the target process. (Citation: MalwareTech Power Loader Aug 2013) (Citation: WeLiveSecurity Gapz and Redyms Mar 2013)
kill_chain_phases: kill_chain_name: mitre-attack
phase_name: defense-evasion
kill_chain_name: mitre-attack
phase_name: privilege-escalation
x_mitre_attack_spec_version: 3.2.0
x_mitre_deprecated: no
x_mitre_domains: enterprise-attack
x_mitre_is_subtechnique: no
x_mitre_modified_by_ref: identity--c78cb6e5-0c4b-4611-8297-d1b8b55e40b5
x_mitre_platforms: Windows
x_mitre_version: 1.1