Hlux

Overview

Trojan:Win32/Hlux (more commonly known to the security industry as the **Kelihos botnet**) was a highly sophisticated, notoriously resilient peer-to-peer (P2P) botnet. Operating for nearly a decade before its infrastructure was dismantled, Hlux/Kelihos was responsible for massive spam campaigns (billions of emails daily), stealing cryptocurrency wallets, harvesting credentials, and acting as a dropper for other malware families. Its decentralized architecture made it exceptionally difficult to take down.

Understanding Hlux (Kelihos) and P2P Botnets
To an end-user, a Hlux infection might go unnoticed, or result in slower internet speeds due to the background network activity. For a network administrator and law enforcement, Hlux represents a massive distributed threat. Unlike traditional botnets that rely on centralized Command and Control (C2) servers (which can be seized), Hlux nodes communicate with each other. Each infected machine acts as a router, passing encrypted instructions and spam templates between peers.

Execution and Decentralized Networking
Hlux was heavily distributed via drive-by downloads, exploit kits, and its own malspam campaigns (`T1566.001`). Upon execution, the payload establishes persistence (`T1547.001`) and injects its core routines into legitimate system processes (`T1055`). The critical phase is the network bootstrap: the malware uses a hardcoded list of IP addresses to contact the P2P network (`T1090`). Once connected, it downloads the latest list of active peers and receives encrypted tasks (`T1573`). These tasks included sniffing network traffic to steal FTP/email credentials (`T1040`), searching the hard drive for Bitcoin wallet files (`T1005`), and acting as an SMTP relay to blast out spam promoting pump-and-dump stock scams or pharmaceutical fraud (`T1098.002`).

Indicators of Compromise & Impact
The impact includes severe bandwidth consumption, IP blacklisting, and credential theft. Host-based IoCs include EDR alerts for injected processes creating massive amounts of outbound network connections to seemingly random IP addresses (other infected peers). Network IoCs are characterized by constant, encrypted UDP and TCP traffic on non-standard ports communicating with a wide variety of global IPs, rather than a single C2 domain.

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

Sigma Rule

title: Suspicious Hlux Activity
id: c3967088977a5997d4808f438b737bd7
status: experimental
description: Detects generic indicators of the hlux malware family.
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith:
            - '\cmd.exe'
            - '\powershell.exe'
        CommandLine|contains:
            - "*hlux*"
    condition: selection
level: medium

Containment & Response Steps

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

1. Immediately isolate the infected endpoint from the network to stop it from participating in the P2P network and generating spam.
2. Assume all web and FTP credentials stored on the machine have been harvested and force immediate resets.
3. Analyze firewall logs to identify the P2P traffic patterns; block the heavily utilized non-standard ports used by the specific Kelihos variant.
4. If cryptocurrency wallets were present on the machine, consider them compromised.

What to Avoid

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

1. Do not rely solely on blocking domain names to stop Hlux; its P2P architecture relies on direct IP-to-IP communication, bypassing DNS.
2. Avoid leaving the machine online for observation unless properly sandboxed, as it will actively contribute to global spam and DDoS campaigns.

References & External Analysis

• Search "hlux" on VirusTotal (External Analysis)

Frequently Asked Questions

Related Families (Category: trojan)

Explore other malware families in the same category:

• Gamania
• Bancteian
• Deceptpcclean
• Polip
• Mailspy

Machine-readable

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