Runner
Table of Contents
Overview
Runner (classified in antimalware telemetry under signatures including Trojan:Win32/Runner, TrojanDownloader:Win32/Runner, and Trojan.Runner) is an obfuscated multi-stage Windows execution stager and payload loader. Distributed through malicious email spam attachments, cracked software packages, and exploit kit landings, Runner is engineered to bootstrap more complex malware families (such as infostealers, banking trojans, and ransomware). Upon initial execution, Runner conducts anti-sandbox environment checks (evaluating CPU core counts, virtual machine MAC address ranges, and memory sizes). It dynamically decodes embedded shellcode or downloads encrypted secondary payloads from attacker-controlled C2 servers via HTTP/HTTPS GET requests. Runner achieves persistence by creating scheduled tasks (schtasks /create) or writing autostart registry keys, executing secondary payloads through process injection (such as process hollowing or asynchronous procedure call injection) into legitimate Windows binaries like svchost.exe or explorer.exe.
Known aliases
Threat reports may refer to this family under multiple names:
Family Pedigree & Lineage
Malware authors regularly fork and iterate upon existing codebases. Observed upstream lineage and downstream variants for this family include:
Known Derivatives & Downstream Variants: Trojan:Win32/Runner.A · Trojandownloader:Win32/Runner.B
MITRE ATT&CK Techniques
This family has been observed using the following ATT&CK techniques: T1059.003 · T1055.012 · T1053.005 · T1105 · T1497
Tactical Mitigations
Based on the techniques used by this family, consider the following defensive strategies:
- T1059.003: Restrict execution of Windows Command Shell (cmd.exe) and block unauthorized batch scripts.
- T1105: Implement network intrusion detection systems (NIDS) and host-based firewalls to block unauthorized inbound or outbound file transfers.
MITRE D3FEND™ Defensive Countermeasures
Defensive techniques mapped to counter the offensive tradecraft observed in this family (via the MITRE D3FEND matrix):
| D3FEND ID | Countermeasure Name | Tactic | Countered ATT&CK | Defensive Guidance |
|---|---|---|---|---|
D3-STM | Scheduled Task Creation Analysis | Detect | T1053.005 | Audit task creation targeting system and hidden service directories; verify task author credentials. |
D3-PHA | Process Hollowing Analysis | Detect | T1055.012 | Inspect unbacked executable memory regions (PAGE_EXECUTE_READWRITE) for replaced PE image headers inside legitimate host processes. |
D3-PBA | Process Spawn Analysis | Detect | T1059.003 | Inspect command-line arguments and anomalous parent-child relationships spawning from cmd.exe. |
D3-NTI | Network Traffic Inspection | Detect | T1105 | Inspect deep packet payloads for anomalous staging binaries and unauthorized egress protocols. |
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:
Tier 1 Primitive Artifact Rule (Fast Triage)
Matches raw strings and file markers. Vulnerable to binary repacking and simple obfuscation.
rule MALWARE_WIN_RUNNER_T1_ARTIFACT {
meta:
description = "Tier 1 Primitive Artifact: Raw string matches for Runner"
tier = "T1 - Primitive Artifact"
confidence = "Low-Medium (Fast Triage)"
author = "SystemHelpdesk Threat Research Desk"
date = "2026-10-14"
strings:
$s1 = "runner" ascii wide nocase
$s2 = "trojan:win32/runner" ascii wide nocase
$s3 = "trojandownloader:win32/runner" ascii wide nocase
$s4 = "win32/runner" ascii wide nocase
$s5 = "runner loader" ascii wide nocase
$s6 = "runner stager" ascii wide nocase
condition:
uint16(0) == 0x5a4d and any of them
}Tier 2 Behavioral Context Rule (Process Chains & Sigma)
Tracks parent-child process anomalies and suspicious scripting telemetry. Resilient against file renames.
title: SystemHelpDesk Detection - Runner (Trojan) Execution & Triage
id: 18afcf01-b076-5588-a5d6-461be17f3670
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
with the Runner 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/runner
- 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.t1059_003
- attack.t1055_012
- attack.t1053_005
- attack.t1105
- attack.t1497
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: mediumTier 3 Attribution Fingerprint Rule (High Fidelity)
Deep signature matching distinctive operational fingerprints and payload characteristics.
rule MALWARE_WIN_RUNNER_T3_ATTRIBUTION {
meta:
description = "Tier 3 Attribution Fingerprint: Heuristic detection for Runner 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 = "runner" 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
}References & External Analysis
- Microsoft Defender Threat Encyclopedia - Trojan:Win32/Runner
- Trend Micro Threat Encyclopedia - Trojan.Win32.Runner
- Search "runner" on VirusTotal (External Analysis)
- Search "runner" on Any.Run (Sandbox Sandbox)
- Search "runner" on MalwareBazaar (Malware Samples)
Frequently Asked Questions
What is Trojan:Win32/Runner?
Runner is a multi-stage Windows trojan loader that downloads and executes secondary malware via process injection.
How does Runner inject secondary malware into memory?
It uses process hollowing and QueueUserAPC injection to run decrypted shellcode inside legitimate processes like svchost.exe.
How is Runner delivered to victim systems?
It spreads through phishing emails with weaponized attachments, malicious torrents, and Trojanized cracks.
How does Runner evade automated malware analysis sandboxes?
It checks for virtual machine artifacts, examines screen resolution, and enforces sleep delays to defeat sandboxes.
What are the recommended containment steps for Runner?
Isolate the endpoint, capture memory dumps of injected processes, delete scheduled tasks, and block outbound C2 IPs.
How do I remove the Runner Trojan from Windows?
Manual removal of Runner 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 Runner a virus or a Trojan?
Runner is classified as a Trojan. Unlike traditional viruses that infect files, modern malware like Runner typically operates as a standalone payload designed to compromise systems, steal data, or deploy secondary stage implants.
What are the main symptoms of a Runner infection?
Symptoms of Runner 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.
Protect Your Network Against Trojans
Want to prevent Runner and similar threats from compromising your organization? Read our comprehensive defensive guide: Banking Trojan Protection for Businesses.
📣 Threat Intel Correction or Update?
Notice an outdated IOC, unlisted alias, or disputed attribution? Threat researchers are invited to propose an update on GitHub or contact the SystemHelpDesk research desk. All community revisions are credited in our public CHANGELOG.
Machine-readable
Get this profile as JSON: https://malware-families-catalog.systemhelpdesk.com/api/runner.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.