Napolar
Table of Contents
Overview
Trojan:Win32/Napolar (also widely tracked as Solarbot) is a highly sophisticated banking trojan and botnet client that gained prominence around 2013. It is designed to establish deep persistence, steal financial credentials via web-injects (`T1185`), launch Distributed Denial of Service (DDoS) attacks, and function as a modular platform for downloading additional payloads. Its sophisticated evasion techniques made it highly effective against traditional antivirus solutions.
Understanding Napolar (Advanced Botnets)
To an end-user, a Napolar infection is entirely invisible. For a security operations center (SOC), it is a critical threat indicating a complete loss of endpoint integrity. Napolar isn't just a credential stealer; it effectively turns the compromised host into a node in a global cybercriminal infrastructure, capable of launching attacks against third parties.
Execution and Evasion Mechanics
Napolar was distributed via exploit kits (like Blackhole) or malspam (`T1566.001`). Its defining characteristic is its aggressive defense evasion. Upon execution, it performs deep process injection (`T1055`), often utilizing advanced API unhooking techniques to bypass user-land EDR sensors. It injects into `explorer.exe` and web browser processes (Chrome, Firefox, IE). Once hooked into the browser, it performs form-grabbing and web-injects (`T1185`) to steal banking credentials as they are typed. It communicates with a Tor-hosted C2 server or uses DGA (Domain Generation Algorithms) (`T1568.002`) to receive commands, which may include downloading massive executable files to participate in HTTP/UDP flood DDoS attacks (`T1498`).
Indicators of Compromise & Impact
The primary impact is the catastrophic theft of financial data and the endpoint being co-opted for DDoS operations. Host-based IoCs are subtle due to advanced injection, but memory analysis will reveal unsigned DLLs loaded into core system processes. EDR may catch anomalous API unhooking attempts. Network IoCs include the browser processes making unexpected connections to Tor exit nodes (if not configured to do so) or massive, sudden spikes in outbound UDP traffic indicative of a DDoS attack.
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 |
|---|---|---|---|
T1185 | Browser Session Hijacking (Web-injects for credential theft) | Collection | ATT&CK ↗ |
T1055 | Process Injection (Advanced injection and API unhooking) | Defense Evasion | ATT&CK ↗ |
T1498 | Network Denial of Service (Participating in botnet DDoS attacks) | Impact | ATT&CK ↗ |
T1568.002 | Dynamic Resolution: Domain Generation Algorithms (DGA for C2 resilience) | Command and Control | ATT&CK ↗ |
Tactical Mitigations
Based on the techniques used by this family, consider the following defensive strategies:
- T1185: Enforce strong MFA and use browser isolation or hardened browsers for sensitive financial or administrative portals to defeat session hijacking.
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-PIAD | Process Injection Analysis & Detection | Detect | T1055 | Monitor cross-process thread creation (CreateRemoteThread) and asynchronous procedure calls (QueueUserAPC). |
D3-MitBA | Man-in-the-Browser Analysis | Detect | T1185 | Deploy browser extension whitelisting and hardware-backed session binding to prevent rogue DOM and socket injection. |
D3-TR | Traffic Rate Limiting | Isolate | T1498 | Deploy BGP Flowspec and edge scrubbing proxies to automatically throttle volumetric SYN and UDP reflection attacks. |
D3-DNSR | DNS Reputation Analysis | Detect | T1568.002 | Deploy recursive DNS security resolvers with algorithmic domain scoring (entropy and n-gram models) to automatically sinkhole DGA queries. |
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_NAPOLAR_T1_ARTIFACT {
meta:
description = "Tier 1 Primitive Artifact: Raw string matches for Napolar"
tier = "T1 - Primitive Artifact"
confidence = "Low-Medium (Fast Triage)"
author = "SystemHelpdesk Threat Research Desk"
date = "2026-10-14"
strings:
$s1 = "napolar" 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 - Napolar (Trojan) Execution & Triage
id: 8f736a2f-aff6-5ce5-bade-50e42cd8e1b2
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
with the Napolar 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/napolar
- 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.t1568_002
- attack.t1185
- attack.t1498
- attack.t1055
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_NAPOLAR_T3_ATTRIBUTION {
meta:
description = "Tier 3 Attribution Fingerprint: Heuristic detection for Napolar 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 = "napolar" 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 compromised endpoint; a Napolar infection means the host is actively controlled by an advanced threat actor.
- Do not attempt manual cleanup; the deep API hooks require a complete forensic wipe and operating system reinstallation.
- Contact affected financial institutions to freeze accounts and reverse transactions, assuming all banking credentials have been compromised.
- Analyze DNS logs for DGA-like requests to identify other potentially infected nodes on the enterprise network.
What to Avoid
Common mistakes during response to this family that can destroy evidence, spread the infection, or worsen recovery.
- Do not trust the integrity of a system after a Napolar infection; its API unhooking capabilities render local AV scans unreliable.
- Avoid relying solely on static IP blocking for the C2; the botnet utilizes DGA and Tor to maintain connectivity.
References & External Analysis
- Search "napolar" on VirusTotal (External Analysis)
- Search "napolar" on Any.Run (Sandbox Sandbox)
- Search "napolar" on MalwareBazaar (Malware Samples)
Frequently Asked Questions
What is Napolar and what threat category does it belong to?
Napolar 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 Napolar establish persistence and evade defensive controls?
Napolar 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 Napolar compromise?
Security teams responding to Napolar 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 Napolar?
Napolar 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 Napolar across enterprise endpoints?
Defenders should hunt for Napolar 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 Napolar Trojan from Windows?
Manual removal of Napolar 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 Napolar a virus or a Trojan?
Napolar is classified as a Trojan. Unlike traditional viruses that infect files, modern malware like Napolar typically operates as a standalone payload designed to compromise systems, steal data, or deploy secondary stage implants.
What are the main symptoms of a Napolar infection?
Symptoms of Napolar 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 Napolar 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/napolar.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.