Multiinjector

Overview

HackTool:Win32/Multiinjector (or Trojan:Win32/Multiinjector) describes a specialized utility or a component of a larger malware framework whose primary, explicit purpose is to perform Process Injection (`T1055`). It is designed to take malicious shellcode or a DLL and forcefully insert it into the memory space of a legitimate, running Windows process (like `explorer.exe`, `svchost.exe`, or a browser) to evade detection and bypass firewall rules.

Understanding Multiinjector (Injection Frameworks)
To an end-user, the infection is completely invisible. For a security analyst, the presence of a 'Multiinjector' tool indicates a sophisticated adversary attempting to establish a stealthy foothold. Because the malicious code runs *inside* a trusted process, it inherits the permissions and network access rights of that process, blinding many legacy security tools.

Execution and Injection Mechanics
Multiinjector tools utilize various Windows API techniques to accomplish their goal (`T1055`). Common methods include DLL Injection (using `CreateRemoteThread` and `LoadLibrary`), Process Hollowing (creating a suspended legitimate process, carving out its memory, and replacing it with the payload), or AtomBombing. By injecting into a browser process (`chrome.exe`), the malware can make outbound C2 connections that appear perfectly legitimate to network firewalls (`T1562.004`).

Indicators of Compromise & Impact
The impact is stealthy execution of secondary payloads (like RATs or credential stealers). Host-based IoCs are difficult to detect without EDR. Look for anomalous API calls (e.g., a process unexpectedly calling `VirtualAllocEx` or `WriteProcessMemory` on another process). Network IoCs involve legitimate processes (like `notepad.exe` or `svchost.exe`) making unexpected, persistent outbound connections to unknown IP addresses on non-standard ports.

MITRE ATT&CK Techniques

Observed techniques used by this family, mapped to the MITRE ATT&CK framework:

Generated Detections (Boilerplate)

These YARA and Sigma rules are auto-generated based on the family name and aliases. They must be heavily tuned before deployment in a production environment.

YARA Rule

rule MALWARE_WIN_MULTIINJECTOR {
    meta:
        description = "Detects Multiinjector (trojan)"
        author = "SystemHelpdesk Boilerplate Generator"
        date = "2026-07-06"
    strings:
        $s1 = "multiinjector" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

Sigma Rule

title: Suspicious Multiinjector Activity
id: 138472ec212b114fba2c0eafba32c4e6
status: experimental
description: Detects generic indicators of the multiinjector malware family.
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith:
            - '\cmd.exe'
            - '\powershell.exe'
        CommandLine|contains:
            - "*multiinjector*"
    condition: selection
level: medium

Containment & Response Steps

Ordered checklist for responders. Adapt to your environment and engage professional support for active incidents.

1. Isolate the endpoint immediately; the presence of an injector means a hidden payload is actively running in memory.
2. Capture a full memory dump (RAM) of the system *before* rebooting or killing processes, as the payload only exists in memory.
3. Use memory analysis tools (like Volatility) to scan for injected threads or hollowed processes to extract the actual payload.
4. Ensure your EDR is configured with aggressive rules against cross-process memory manipulation.

What to Avoid

Common mistakes during response to this family that can destroy evidence, spread the infection, or worsen recovery.

1. Do not assume the threat is neutralized simply by deleting the injector executable on disk; the payload is already running inside another process.
2. Avoid relying solely on file-based scanning, as the injected payload is fileless.

References & External Analysis

• Search "multiinjector" on VirusTotal (External Analysis)

Frequently Asked Questions

Related Families (Category: trojan)

Explore other malware families in the same category:

• Apost
• Genericrxfy
• Vundo
• Mailspy
• Sphinx

Machine-readable

Get this profile as JSON: https://jordanricky1604-ship-it.github.io/malware-families-catalog/api/multiinjector.json

Ecosystem & Interactive Environments

This profile is part of the Malware Families Catalog, a public dataset of 2,899 malware families. The catalog is also published across our ecosystem: Hugging Face, Kaggle, Zenodo, Replit, StackBlitz, CodeSandbox, and CodePen.