Riodrv

Overview

Executive Summary

Technical Architecture and Exploitation

• Kernel API Hooking: RioDrv intercepts core Windows API calls (such as `NtQueryDirectoryFile` or `NtEnumerateValueKey`). When a legitimate application (like Windows Explorer or an Antivirus scanner) asks the OS to list the contents of a directory, the rootkit intercepts the request and removes its own hidden files (often prefixed with specific characters, like `$sys$`) from the results.
• Blind Spot Creation: By completely hiding its presence, the rootkit creates a massive "blind spot" on the system.
• Secondary Hijacking: Because the rootkit hides *any* file utilizing its specific naming convention, actual cybercriminals quickly realized they could name their own malware (e.g., Trojans, keyloggers) using the rootkit's prefix. The DRM rootkit would then unwittingly hide the attacker's malware from all security scanners, providing them with perfect, unintentional stealth.

Threat Impact

Remediation and Eradication

• Advanced Memory Forensics: Standard disk forensics will miss rootkit-hidden files. Responders must capture a live memory dump or utilize specialized rootkit unhooking tools to bypass the kernel modifications and identify the hidden drivers.
• Complete System Wipe: Attempting to cleanly "uninstall" a kernel rootkit is highly unreliable and frequently results in a Blue Screen of Death (BSOD) or a corrupted OS. The only cryptographically secure remediation is a complete wipe and re-image of the compromised host from a known good baseline.

Known aliases

Threat reports may refer to this family under multiple names:

• Rootkit.RioDrv
• Win32/Sony.Rootkit
• Rootkit.Win32.Agent

MITRE ATT&CK Techniques

Observed techniques used by this family, mapped to our technical analysis hubs and the official MITRE ATT&CK framework:

MITRE D3FEND™ Defensive Countermeasures

Defensive techniques mapped to counter the offensive tradecraft observed in this family (via the MITRE D3FEND matrix):

Tiered Detection Rules (Cisco CAIRN Model)

Modern threat detection requires multi-layered rule engineering. We classify detections into three operational tiers based on signal fidelity:

rule MALWARE_WIN_RIODRV_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Riodrv"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "riodrv" ascii wide nocase
        $s2 = "rootkit.riodrv" ascii wide nocase
        $s3 = "win32/sony.rootkit" ascii wide nocase
        $s4 = "rootkit.win32.agent" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Riodrv (Trojan) Execution & Triage
id: 284fb174-e363-55a0-a818-169648071274
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Riodrv malware family. Detects suspicious execution from temporary user
  directories with hidden window flags and background transfer utilities.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/riodrv
- https://malware-families-catalog.systemhelpdesk.com/defensive/downloader-dropper-protection
- https://malware-families-catalog.systemhelpdesk.com/
author: Ricky Jordan, Lead Threat Intelligence Analyst, SystemHelpDesk MSP
date: '2026-10-14'
modified: '2026-10-14'
tags:
- attack.trojan
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1014
- attack.t1562_001
- attack.t1543_003
logsource:
  category: process_creation
  product: windows
detection:
  selection_process:
    Image|endswith:
    - \cmd.exe
    - \powershell.exe
    - \cscript.exe
    - \wscript.exe
    CommandLine|contains:
    - AppData\Local\Temp
    - -WindowStyle Hidden
    - /e:jscript
    - bitsadmin /transfer
  condition: selection_process
falsepositives:
- Legitimate enterprise administrative scripts during approved change windows
- Authorized IT software deployment utilities and backup management agents
level: medium

rule MALWARE_WIN_RIODRV_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Riodrv tradecraft"
        tier = "T3 - Attribution Fingerprint"
        confidence = "High (Confirmed Family Signature)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        // Core family identifier & heuristic payload signatures
        $attrib_str = "riodrv" ascii wide nocase
        $pe_magic = "MZ" ascii
        $net_marker = "http" ascii nocase
    condition:
        uint16(0) == 0x5a4d and ($attrib_str and $net_marker) and filesize < 15MB
}

Containment & Response Steps

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

1. Sever network connectivity for the flagged endpoint to terminate persistent command-and-control (C2) communication channels and stop Riodrv from retrieving secondary stage payloads.
2. Capture process memory triage to detect and terminate malicious threads injected by Riodrv into legitimate system processes such as explorer.exe or svchost.exe.
3. Audit Windows Registry Run keys (HKCU\Software\Microsoft\Windows\CurrentVersion\Run) and Task Scheduler entries to locate and purge Riodrv persistence hooks.
4. Deploy updated enterprise EDR detection signatures and conduct an out-of-band endpoint scan to isolate dropped binaries and staged payloads.
5. Rotate all credentials, domain user passwords, and session cookies active on the system during the Riodrv execution timeframe.

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 incident is resolved simply because an antivirus tool removed the initial Riodrv dropper; always verify that secondary payloads and persistence hooks have been eradicated.
2. Avoid logging in with Domain Admin or privileged credentials on a machine suspected of running Riodrv until memory triage is complete.
3. Do not delay host isolation; automated lateral movement and credential dumping can occur within minutes of initial execution.

References & External Analysis

• Search "riodrv" on VirusTotal (External Analysis)
• Search "riodrv" on Any.Run (Sandbox Sandbox)
• Search "riodrv" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Trojan)

Explore other documented threats in the same operational category:

• Pyspy
• Goldun
• Habbo
• Candyopen
• Yoddos
• Cridex
• Installmate
• Y3K_Rat

Machine-readable

Get this profile as JSON: https://malware-families-catalog.systemhelpdesk.com/api/riodrv.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.