Nymaim
Overview
Nymaim (also known as nymain) is a Windows trojan downloader. As documented by Malpedia (Fraunhofer FKIE), it downloads and runs other malware on affected systems and was one of the primary malware families hosted on the Avalanche infrastructure. A distinguishing feature is that Nymaim displays a localized lockscreen on the victim's machine while it downloads additional malware in the background. According to Malpedia, Nymaim is usually delivered through exploit kits and malvertising.
MITRE ATT&CK Techniques
This family has been observed using the following ATT&CK techniques: T1547.001 T1071.001
Tactical Mitigations
Based on the techniques used by this family, consider the following defensive strategies:
- T1071.001: Implement web filtering and SSL/TLS inspection to detect malicious command and control (C2) traffic hiding in HTTP/HTTPS.
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_NYMAIM {
meta:
description = "Detects Nymaim (downloader)"
author = "SystemHelpdesk Boilerplate Generator"
date = "2026-07-06"
strings:
$s1 = "nymaim" ascii wide nocase
condition:
uint16(0) == 0x5a4d and any of them
}Sigma Rule
title: Suspicious Nymaim Activity
id: 6e680be7a47bed29c2657b2bd819671a
status: experimental
description: Detects generic indicators of the nymaim malware family.
logsource:
category: process_creation
product: windows
detection:
selection:
Image|endswith:
- '\cmd.exe'
- '\powershell.exe'
CommandLine|contains:
- "*nymaim*"
condition: selection
level: mediumReferences & External Analysis
- Malpedia (Fraunhofer FKIE): Nymaim (win.nymaim)
- Search "nymaim" on VirusTotal (External Analysis)
Frequently Asked Questions
What is Nymaim?
Nymaim (also known as nymain) is a Windows trojan downloader. According to Malpedia, its main role is to download and run other malware on infected systems, acting as a delivery mechanism for additional threats.
How does Nymaim spread?
Per Malpedia, Nymaim is usually delivered through exploit kits and malvertising (malicious online advertising). It was also one of the primary malware families hosted on the Avalanche infrastructure, a large criminal hosting network.
What makes Nymaim distinctive?
Malpedia notes that Nymaim is distinctive in that it displays a localized lockscreen to the victim while it downloads additional malware in the background. The lockscreen behavior overlaps with ransomware-style tactics, even though its core function is as a downloader.
What was Nymaim's connection to Avalanche?
According to Malpedia, Nymaim was one of the primary malware families hosted on Avalanche, a large bulletproof-hosting and malware-distribution network. Avalanche was the subject of a major international law-enforcement takedown.
How do I remove the Nymaim Downloader from Windows?
Manual removal of Nymaim 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 Nymaim a virus or a Downloader?
Nymaim is classified as a Downloader. Unlike traditional viruses that infect files, modern malware like Nymaim typically operates as a standalone payload designed to compromise systems, steal data, or deploy secondary stage implants.
What are the main symptoms of a Nymaim infection?
Symptoms of Nymaim 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: downloader)
Explore other malware families in the same category:
Protect Your Network Against Downloaders
Want to prevent Nymaim and similar threats from compromising your organization? Read our comprehensive defensive guide: Downloader & Dropper Protection.
Machine-readable
Get this profile as JSON: https://jordan123234-malware-families-explorer.static.hf.space/api/nymaim.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.