Flinject

Category: ransomware · Aliases: Trojan.Inject, Injector.FLInject, Win32/Injector · Sample count (EMBER 2018): 1 · Enrichment: insufficient_information · Updated: 2026-07-02T07:03:23Z

Category: RansomwareActor: Unknown / CybercriminalIndustry: Global / OpportunisticMotivation: Opportunistic

Overview

Executive Summary

FLInject (often flagged as Trojan.Inject or Injector.FLInject) is a specific, malicious utility designed solely to perform code injection. It is not typically a standalone malware payload (like an info-stealer or ransomware), but rather the delivery mechanism used by other malware to stealthily inject their malicious code into legitimate, running Windows processes to evade detection.

Infection Vector and Technical Capabilities

FLInject is usually embedded within a larger malware framework or dropped by an initial downloader (like a malicious macro in a Word document). It is executed silently in the background. Upon execution, FLInject's sole purpose is advanced evasion:

Process Hollowing/Injection: The core function of FLInject is to target a legitimate Windows process (commonly `svchost.exe`, `explorer.exe`, or `vbc.exe`). It starts the legitimate process in a suspended state, unmaps (hollows out) the legitimate memory, injects the malicious payload into that memory space, and then resumes the process.
Bypassing Whitelists: Because the malicious code is now running from within the memory space of a trusted, digitally signed Microsoft process, application whitelisting (like AppLocker) and many legacy antivirus solutions will allow it to run and communicate with the internet without raising alerts.
API Hooking Evasion: Advanced variants of FLInject utilize "direct syscalls" (system calls) to interact with the Windows kernel, bypassing user-mode API hooks placed by EDR solutions designed to monitor process injection.

Threat Assessment

The detection of an injection tool like FLInject is a severe security incident. It is absolute proof that a sophisticated malware payload is actively attempting to hide on the system. The primary threat is not the injector itself, but the unknown payload (e.g., a banking trojan, ransomware, or RAT) it has successfully hidden within a legitimate process.

Incident Response and Remediation

Memory Forensics (EDR): Immediate network isolation is required. Eradication relies heavily on EDR tools capable of deep memory scanning to identify which legitimate process has been hollowed out and to extract the injected payload for analysis.
Threat Hunting: Assume the payload was successful. Hunt for secondary indicators, such as anomalous outbound network connections originating from `svchost.exe` or `explorer.exe`.
Complete Re-imaging: Because process injection indicates a deep compromise of the operating system's integrity, attempting to terminate the process and "clean" the system is highly risky. A complete bare-metal wipe and re-image from a trusted baseline is necessary.

Known aliases

Threat reports may refer to this family under multiple names:

MITRE ATT&CK Techniques

This family has been observed using the following ATT&CK techniques: T1055 T1055.012

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_FLINJECT {
    meta:
        description = "Detects Flinject (ransomware)"
        author = "SystemHelpdesk Boilerplate Generator"
        date = "2026-07-06"
    strings:
        $s1 = "flinject" ascii wide nocase
        $s2 = "trojan.inject" ascii wide nocase
        $s3 = "injector.flinject" ascii wide nocase
        $s4 = "win32/injector" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

Sigma Rule

title: Suspicious Flinject Activity
id: 6416bd5e5cab3b2d5cfe2f7f2d85481a
status: experimental
description: Detects generic indicators of the flinject malware family.
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith:
            - '\cmd.exe'
            - '\powershell.exe'
        CommandLine|contains:
            - "*flinject*"
            - "*trojan.inject*"
            - "*injector.flinject*"
            - "*win32/injector*"
    condition: selection
level: medium

References & External Analysis

Search "flinject" on VirusTotal (External Analysis)

Frequently Asked Questions

How do I remove the Flinject Ransomware from Windows?

Manual removal of Flinject is highly discouraged as it may leave persistence mechanisms intact. We recommend disconnecting the device from the internet and utilizing a professional incident response service or enterprise-grade EDR software to conduct a full forensic sweep.

Is Flinject a virus or a Ransomware?

Flinject is classified as a Ransomware. Unlike traditional viruses that infect files, modern malware like Flinject typically operates as a standalone payload designed to compromise systems, steal data, or deploy secondary stage implants.

What are the main symptoms of a Flinject infection?

Symptoms of Flinject can include unexpected system slowness, unauthorized outbound network traffic to unknown IP addresses, disabled security software, and suspicious background processes running from AppData or Temp directories.

Related Families (Category: ransomware)

Explore other malware families in the same category:

Protect Your Network Against Ransomwares

Want to prevent Flinject and similar threats from compromising your organization? Read our comprehensive defensive guide: Ransomware Protection Guide.

Need help with an active incident? Published by the SystemHelpdesk team.

Machine-readable

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