# 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.

- Skill: `cyberstrikeus/t1055-003-thread-execution-hijacking` (Agent Skill)
- Install (CLI): `npx skillmds@latest add cyberstrikeus/t1055-003-thread-execution-hijacking`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cyberstrikeus/t1055-003-thread-execution-hijacking/raw
- Safety review: PASS (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: cyberstrikeus (https://skillmd.com/u/cyberstrikeus)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/cyberstrikeus/t1055-003-thread-execution-hijacking

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# T1055.003 Thread Execution Hijacking

> **Sub-technique of:** T1055

## High-Level Description

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 <code>OpenThread</code>. At this point the process can be suspended then written to, realigned to the injected code, and resumed via <code>SuspendThread </code>, <code>VirtualAllocEx</code>, <code>WriteProcessMemory</code>, <code>SetThreadContext</code>, then <code>ResumeThread</code> respectively.

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.

## Kill Chain Phase

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

**Platforms:** Windows

## What to Check

- [ ] Identify if Thread Execution Hijacking technique is applicable to target environment
- [ ] Check Windows systems for indicators of Thread Execution Hijacking
- [ ] 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](https://github.com/redcanaryco/atomic-red-team) and provide actionable ways to test this technique:

### Atomic Test 1: Thread Execution Hijacking

This test injects a MessageBox shellcode generated by msfvenom in Notepad.exe using Thread Execution Hijacking. When successful, a message box will appear with the "Atomic Red Team" caption after one or two seconds.

**Supported Platforms:** windows

```powershell
$notepad = Start-Process notepad -passthru
Start-Process "$PathToAtomicsFolder\T1055.003\bin\InjectContext.exe"
Start-Sleep -Seconds 5
Stop-Process $notepad.id
```

### Manual Testing

If Atomic Red Team tests are not applicable, manually verify the technique by:

1. **Identify Attack Surface**: Determine if the target environment is susceptible to Thread Execution Hijacking by examining the target platforms (Windows).

2. **Assess Existing Defenses**: Review whether mitigations for T1055.003 are in place. If defenses are absent or misconfigured, this technique may be exploitable.

3. **Execute Test**: Use tools and methods described in the MITRE ATT&CK page and external references below.

## Remediation Guide

### 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.

## Detection

### Behavioral Detection of Thread Execution Hijacking via Thread Suspension and Context Switching

## Risk Assessment

| Finding                                         | Severity | Impact          |
| ----------------------------------------------- | -------- | --------------- |
| Thread Execution Hijacking technique applicable | High     | Defense Evasion |

## CWE Categories

| CWE ID  | Title                        |
| ------- | ---------------------------- |
| CWE-693 | Protection Mechanism Failure |

## References

- [Elastic Process Injection July 2017](https://www.endgame.com/blog/technical-blog/ten-process-injection-techniques-technical-survey-common-and-trending-process)
- [Atomic Red Team - T1055.003](https://github.com/redcanaryco/atomic-red-team/tree/master/atomics/T1055.003)
- [MITRE ATT&CK - T1055.003](https://attack.mitre.org/techniques/T1055/003)