Hlux
Table of Contents
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 our technical analysis hubs and the official MITRE ATT&CK framework:
| Technique | Name | Tactic | Official Spec |
|---|---|---|---|
T1090 | Proxy: Peer-to-Peer Routing (P2P Botnet architecture) | Command and Control | ATT&CK ↗ |
T1098.002 | Account Manipulation: Additional Email Delegate Permissions (Mass spamming) | Credential Access | ATT&CK ↗ |
T1040 | Network Sniffing (Stealing credentials in transit) | Credential Access | ATT&CK ↗ |
T1573 | Encrypted Channel (P2P communication) | Command and Control | ATT&CK ↗ |
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-NSA | Network Sniffing Detection | Detect | T1040 | Audit promiscuous mode network interface state changes and enforce end-to-end internal traffic encryption. |
D3-OAA | Outbound Network Traffic Filtering | Isolate | T1090 | Restrict outbound connections to known external proxy relays and enforce enterprise forward proxy authentication. |
D3-EAM | Email Access Auditing | Detect | T1098.002 | Continuously monitor and alert on unauthorized mailbox forwarding rules and OAuth application permissions. |
D3-NTI | Encrypted Traffic Analysis | Detect | T1573 | Inspect TLS handshake metadata (JA3/JA4 fingerprints) to identify malicious encrypted C2 sessions. |
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_HLUX_T1_ARTIFACT {
meta:
description = "Tier 1 Primitive Artifact: Raw string matches for Hlux"
tier = "T1 - Primitive Artifact"
confidence = "Low-Medium (Fast Triage)"
author = "SystemHelpdesk Threat Research Desk"
date = "2026-10-14"
strings:
$s1 = "hlux" 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 - Hlux (Trojan) Execution & Triage
id: b10dd836-4d70-55f9-8fc1-1ed6de5b97b0
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
with the Hlux 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/hlux
- 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.t1098_002
- attack.t1573
- attack.t1040
- attack.t1090
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_HLUX_T3_ATTRIBUTION {
meta:
description = "Tier 3 Attribution Fingerprint: Heuristic detection for Hlux 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 = "hlux" 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.
- Immediately isolate the infected endpoint from the network to stop it from participating in the P2P network and generating spam.
- Assume all web and FTP credentials stored on the machine have been harvested and force immediate resets.
- Analyze firewall logs to identify the P2P traffic patterns; block the heavily utilized non-standard ports used by the specific Kelihos variant.
- 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.
- Do not rely solely on blocking domain names to stop Hlux; its P2P architecture relies on direct IP-to-IP communication, bypassing DNS.
- 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)
- Search "hlux" on Any.Run (Sandbox Sandbox)
- Search "hlux" on MalwareBazaar (Malware Samples)
Frequently Asked Questions
What is Hlux and what threat category does it belong to?
Hlux is classified as a Trojan. Documented across security telemetry, it is engineered to execute unauthorized operations, establish persistent footholds on target endpoints, and facilitate malicious campaigns targeting enterprise and individual environments.
How does Hlux establish persistence and evade defensive controls?
Hlux typically establishes persistence through registry run keys, scheduled tasks, or service installations, while evading signature-based antivirus solutions through code obfuscation, memory injection, or anti-analysis sandbox checks.
What are the essential incident response steps for mitigating a Hlux compromise?
Security teams responding to Hlux should immediately isolate affected endpoints from the network, perform memory triage to capture volatile forensic artifacts, audit registry and startup persistence mechanisms, revoke exposed user credentials, and restore systems from verified, clean backups.
What secondary payloads and staging behaviors are commonly associated with Hlux?
Hlux frequently operates as a loader or dropper designed to establish a foothold before downloading and executing secondary high-impact malware payloads. Depending on the threat actor's objectives, these dropped modules can range from ransomware and banking injects to modular infostealers and remote management backdoors.
How can security operations teams effectively detect and hunt for Hlux across enterprise endpoints?
Defenders should hunt for Hlux by deploying behavioral endpoint detection and response (EDR) rules that monitor suspicious process spawning (such as cmd.exe or powershell.exe spawned from office documents or temporary directories), anomalous outbound network connections from non-browser binaries, and unauthorized modifications to Windows Run keys and scheduled task registries.
How do I remove the Hlux Trojan from Windows?
Manual removal of Hlux 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 Hlux a virus or a Trojan?
Hlux is classified as a Trojan. Unlike traditional viruses that infect files, modern malware like Hlux typically operates as a standalone payload designed to compromise systems, steal data, or deploy secondary stage implants.
What are the main symptoms of a Hlux infection?
Symptoms of Hlux 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 Hlux 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/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.