How to Remove Smoke Loader Trojan: Complete Removal Guide

Smoke Loader is a sophisticated trojan-type malware used as a downloader to proliferate various other malicious programs on infected systems. This comprehensive guide provides detailed technical analysis, distribution methods, removal instructions, and prevention strategies for those affected by this dangerous threat. By following our step-by-step methodology, you’ll learn how Smoke Loader operates, how to safely remove it from your system, and how to prevent future infections.

Common Names	Avast: Win32:Trojan-gen BitDefender: Gen:Variant.Symmi.67297 ESET-NOD32: Win32/TrojanDownloader.Zurgop.CB Kaspersky: Trojan.Win32.Sharik.xig Microsoft: Trojan:Win32/Smoke.C!lod
Type	Trojan, Downloader, Malware Distributor, Information Stealer
First Detected	2011 (original variant), actively updated through 2025
Platforms Affected	Windows 7, Windows 8.1, Windows 10, Windows 11
Infection Level	Critical
Data Risk	Severe – Downloads additional malware, steals sensitive information, adds system to botnets
Distribution Methods	Phishing emails (malicious attachments), malicious advertisements, software cracks, exploit kits
Secondary Infections	XMR Miner, Avaddon ransomware, njRAT malware, information stealers
Symptoms	Often runs stealthily with minimal visible symptoms, system slowdowns, unusual network activity

What is Smoke Loader Trojan?

Smoke Loader is a versatile trojan-type malware that functions primarily as a downloader for other malicious software. According to Microsoft Security researchers, this advanced trojan infiltrates systems without users’ consent, typically through spam emails containing malicious attachments. Once established on a system, Smoke Loader performs several sophisticated actions to maintain persistence and avoid detection.

What makes Smoke Loader particularly dangerous is its ability to download and execute additional malware payloads, which can include cryptocurrency miners, ransomware, banking trojans, and data stealers. These secondary infections often cause significant damage to the victim’s system, privacy, and financial security. The trojan has been active since at least 2011 and has undergone numerous updates, making it one of the longest-running and most evolved malware families in circulation today.

According to Malpedia’s threat analysis, Smoke Loader is frequently sold in underground forums and has been used in multiple high-profile malware campaigns, with its modular architecture allowing attackers to customize their deployments based on their specific goals.

Interesting Facts About Smoke Loader

• Smoke Loader employs advanced techniques to update itself and remove execution traces to evade detection
• The malware modifies file creation/modification dates to prevent discovery through recently modified file lists
• It blocks access to its own executable by removing read/write permissions
• The trojan uses traffic obfuscation techniques, sending requests to legitimate URLs to disguise C2 server communications
• Smoke Loader has been associated with multiple major cybercrime groups and has been used to distribute various payloads over its long history
• The malware is regularly updated with new evasion techniques to bypass security solutions

Smoke Loader Statistics

Based on data collected from cybersecurity reports and threat intelligence:

• Smoke Loader infections have been documented in over 40 countries, with particularly high concentrations in Eastern Europe and North America
• The trojan has been used to distribute more than 10 different malware families including cryptominers, banking trojans, and ransomware, as documented in CIS’s threat intelligence reports
• According to Cybereason’s research, specific Smoke Loader campaigns have achieved infection rates of up to 30,000 systems in a single month
• Microsoft’s Defender team reports that Smoke Loader infections often lead to 2-5 additional malware payloads being installed on a victim’s system
• The average dwell time (time before detection) for Smoke Loader infections exceeds 3 weeks

How Smoke Loader Trojan Spreads

Smoke Loader uses several distribution methods to infect systems:

• Phishing emails with malicious attachments (particularly MS Office documents presented as job applications or other work-related files)
• Malicious online advertisements that redirect to exploit kits
• Software cracking tools and pirated software from unofficial sources
• Social engineering tactics that trick users into downloading and executing malicious files
• Compromised websites that host exploit kits targeting browser vulnerabilities
• Bundling with seemingly legitimate software (deceptive “bundling” marketing methods)

The most common infection vector involves spam emails containing Microsoft Office documents with malicious macros. When a user opens these documents, they are prompted to “enable macros” or “enable content” to view the document properly. Once enabled, these macros execute scripts that connect to remote servers and download the Smoke Loader trojan.

Signs of Smoke Loader Infection

Smoke Loader is designed to operate stealthily, making detection challenging for the average user. However, these symptoms might indicate a Smoke Loader infection:

• Unexplained system slowdowns or resource usage spikes (especially if a cryptocurrency miner was deployed)
• Unusual network activity, even when no applications are actively being used
• Security software or Windows Defender being disabled without user action
• Appearance of unfamiliar processes in Task Manager
• Unexplained crashes or system instability
• Discovery of unknown software installed on the system
• Suspicious outbound connection attempts in firewall logs

According to security experts, Smoke Loader is deliberately designed to minimize visible symptoms, which is why it often remains undetected until secondary malware (like ransomware) activates and causes more obvious damage.

Secondary Payloads Distributed by Smoke Loader

Smoke Loader is known to distribute various types of malware, including:

Malware Type	Examples	Potential Impact
Cryptocurrency Miners	XMR Miner, CoinMiner	System resource depletion, hardware damage from overheating, increased electricity costs
Ransomware	Avaddon, STOP/Djvu	File encryption, data loss, ransom demands
Remote Access Trojans	njRAT, Remcos RAT	Complete system control, surveillance, data theft
Banking Trojans	TrickBot, Emotet	Financial credential theft, unauthorized transactions
Information Stealers	Vidar, Raccoon Stealer	Theft of passwords, cookies, cryptocurrency wallets, sensitive documents

The specific payload deployed often depends on the cybercriminal operation controlling the Smoke Loader instance and their current objectives. A single Smoke Loader infection can lead to multiple different malware types being deployed simultaneously or sequentially.

How to Remove Smoke Loader Trojan

Removing Smoke Loader requires a systematic approach to ensure all components are eliminated from your system. Follow these comprehensive removal steps:

1. Immediate Steps After Infection

1. Disconnect from networks: Immediately disconnect your computer from all networks, including Wi-Fi, Ethernet, and Bluetooth to prevent the trojan from communicating with command and control servers and downloading additional payloads
2. Boot into Safe Mode: Restart your computer in Safe Mode to prevent the trojan from running its full capabilities
3. Back up important files: If possible, back up critical files to an external drive, but be cautious not to overwrite existing backups with potentially infected files

2. Removal Using Trojan Killer

Trojan Killer is specifically designed to remove sophisticated malware, including Smoke Loader:

1. Download and install Trojan Killer from the official website on a clean computer and transfer it to the infected machine using a USB drive
2. Boot into Safe Mode with Networking:
   • Restart your computer and press F8 repeatedly (Windows 7) or hold Shift while clicking Restart (Windows 10/11)
   • Select “Safe Mode with Networking” from the advanced startup options
3. Run a system scan:
   • Launch Trojan Killer with administrator privileges
   • Select “Full Scan” option to detect all trojan components
   • Allow the scan to complete (may take 30-60 minutes)
4. Remove detected threats:
   • Review the scan results for Smoke Loader components and secondary infections
   • Select all detected malicious components and click “Remove Selected”
   • Restart your computer when prompted
5. Run a second scan to ensure all malicious components have been removed

3. Manual Removal (For Advanced Users)

Warning: Manual removal of sophisticated trojans is challenging and should only be attempted by users with advanced technical knowledge. For most users, automated removal tools like Trojan Killer are recommended.

Step 1: Identify and Terminate Malicious Processes

1. Press Ctrl+Shift+Esc to open Task Manager
2. Look for suspicious processes, including:
   • Randomly named executables (often with names consisting of random characters)
   • Processes running from temporary folders or the AppData directory
   • Processes with unusually high CPU or network usage
3. Right-click on suspicious processes and select “End Task”
4. For each suspicious process, click “Open File Location” to identify the malware’s location for later removal

Step 2: Use Autoruns to Find Malicious Startup Items

Autoruns is an effective tool for identifying malware persistence mechanisms, as recommended by security experts:

1. Download Autoruns from the Microsoft Sysinternals website
2. Extract and run Autoruns.exe as administrator
3. In Autoruns, click “Options” and uncheck “Hide Empty Locations” and “Hide Windows Entries”
4. Click the “Refresh” icon to populate the list
5. Look for suspicious entries, particularly those with:
   • No verified publisher
   • Unusual or randomly named files
   • Files located in temporary folders or uncommon locations
6. Right-click on suspicious entries and select “Delete” to remove them

Step 3: Delete Malicious Files

Check these common locations for Smoke Loader components:

Step 4: Clean Registry Entries

Warning: Editing the registry incorrectly can cause system problems. Create a backup before proceeding.

Step 5: Restore System Settings

Smoke Loader often disables security features. Re-enable them with these commands:

4. Post-Removal Security Checks

After removing Smoke Loader, perform these additional security steps:

1. Update and run multiple security scans: Use different security tools to ensure complete removal
2. Change all passwords: Assume all passwords stored on the system have been compromised
3. Enable two-factor authentication: Add this extra security layer to critical accounts
4. Monitor financial accounts: Watch for unauthorized transactions for several weeks
5. Check for secondary infections: Run targeted scans for specific payloads known to be distributed by Smoke Loader

Preventing Smoke Loader Infections

To protect your systems against Smoke Loader and similar trojans, implement these preventive measures:

• Exercise email caution: Never open attachments from unknown senders, especially if they contain macros
• Disable Office macros: Configure Microsoft Office to disable macros by default or only allow digitally signed macros
• Keep software updated: Regularly patch operating systems and applications to address security vulnerabilities
• Use strong security software: Install reputable antivirus and anti-malware solutions like Trojan Killer
• Download software only from official sources: Avoid cracked software, which often contains malware
• Implement browser protection: Use ad-blockers and script-blockers to prevent malicious advertisements
• Enable UEFI Secure Boot: This can help prevent certain types of bootkit malware
• Use application whitelisting: Only allow trusted applications to run on your system
• Create regular backups: Maintain offline backups of important data
• User education: Train yourself and others to recognize phishing attempts and social engineering tactics

Following proper cybersecurity practices is essential for preventing not just Smoke Loader, but all types of sophisticated malware that can compromise your data and privacy.

Frequently Asked Questions

How dangerous is Smoke Loader compared to other trojans?

Smoke Loader is considered one of the more sophisticated and dangerous trojans due to its advanced evasion techniques and its role as a downloader for additional malware. Unlike some trojans that have a single purpose, Smoke Loader creates a backdoor for multiple malicious payloads, essentially functioning as a gateway for numerous threats. Its ability to self-update, disguise its communications, and download additional payloads makes it particularly dangerous. The real damage often comes from the secondary infections it facilitates, which can include ransomware, banking trojans, and cryptominers. A single Smoke Loader infection can lead to multiple subsequent infections, creating a complex chain of malware that compounds the damage and complicates removal.

Can Smoke Loader steal my banking information?

While Smoke Loader itself is primarily a downloader trojan, it frequently installs banking trojans as secondary payloads, which are specifically designed to steal financial information. If your system is infected with Smoke Loader, you should assume that your banking credentials, credit card information, and other financial data may have been compromised. Popular banking trojans deployed by Smoke Loader include TrickBot, Emotet, and Dridex, all of which use sophisticated methods to capture banking credentials, including form grabbing, keystroke logging, and web injection techniques. As a precaution, anyone affected by a Smoke Loader infection should immediately change passwords for all financial accounts, enable two-factor authentication where available, and closely monitor account statements for unauthorized transactions. It’s also advisable to contact your financial institutions to alert them to the potential compromise.

What should I do if my business network is infected with Smoke Loader?

A Smoke Loader infection in a business environment requires a more comprehensive response than a home infection due to the potential for lateral movement and widespread compromise. First, isolate affected systems from the network immediately to prevent spread. Second, engage your IT security team or external incident response professionals to conduct a thorough investigation, as Smoke Loader often serves as an initial access point for more targeted attacks. Implement your incident response plan, which should include forensic analysis to determine the full extent of the compromise, systematic malware removal from all affected systems, and potential rebuilding of critically compromised machines. After remediation, conduct a security assessment to identify and address the vulnerabilities that allowed the initial infection. Finally, provide additional security awareness training to staff, focusing on recognizing phishing attempts and following secure email practices, as these are the most common vectors for Smoke Loader infections.

Can my antivirus detect and prevent Smoke Loader infections?

Modern, updated antivirus solutions can detect known variants of Smoke Loader, but the trojan is constantly evolving to evade detection. According to VirusTotal reports, detection rates for new Smoke Loader variants can vary significantly, with some samples initially evading up to 30% of security products. The trojan employs sophisticated evasion techniques, including modifying file timestamps, removing access permissions to its executable, and using moderately encrypted traffic to command and control servers. For maximum protection, security experts recommend a layered defense approach that combines traditional signature-based detection with behavior-based analysis, regular software updates, macro security settings in Office applications, email filtering, and user education. No single security measure can provide complete protection against sophisticated threats like Smoke Loader, which is why defense-in-depth strategies remain crucial for both individuals and organizations.

Technical Details of Smoke Loader Trojan

For security researchers and system administrators, here are the technical aspects of Smoke Loader Trojan based on VMRay’s malware analysis:

Initial Infection Process

Smoke Loader typically follows this sequence during the initial infection:

1. User opens a malicious document with macros or clicks on a malicious link
2. Initial payload is downloaded and executed, often a small downloader
3. The downloader retrieves the main Smoke Loader component
4. Smoke Loader connects to its command and control (C2) server
5. The trojan downloads its latest version to ensure it’s running the most current version with the latest evasion techniques
6. It establishes persistence mechanisms to survive system reboots
7. Finally, it begins downloading and executing additional malware payloads based on instructions from the C2 server

System Modifications

Upon infection, Smoke Loader makes the following system changes:

Network Communication

Smoke Loader communicates with command and control (C2) servers using the following methods:

• Moderately encrypted HTTP/HTTPS traffic to obscure commands
• Sends requests to legitimate websites to disguise malicious traffic
• Uses domain generation algorithms (DGA) in some variants to generate fallback C2 domains
• May use custom protocols over non-standard ports
• Often employs traffic obfuscation techniques to avoid network-based detection

Anti-Analysis Techniques

Smoke Loader employs various techniques to evade detection and analysis:

• Modifies file creation/modification dates to prevent identification through recently changed files
• Removes read/write permissions from its own executable to hinder analysis
• Uses moderate traffic encryption to obscure command and control communications
• Employs anti-VM and anti-sandbox techniques to detect analysis environments
• May inject code into legitimate Windows processes to hide malicious activity
• Uses timing checks to detect debuggers
• Self-updates to ensure it’s running the latest version with current evasion techniques

Indicators of Compromise (IoCs)

Security teams should look for these indicators when hunting for Smoke Loader:

File System Artifacts

Registry Artifacts

Network Indicators

YARA Rule for Detection

The following YARA rule can help detect Smoke Loader Trojan samples:

Advanced YARA Detection Rule

This enhanced detection rule was developed by Malpedia researchers for detecting more evasive Smoke Loader variants:

Conclusion

Smoke Loader Trojan represents a significant threat due to its sophisticated evasion techniques and its role as a gateway for multiple additional malware infections. This trojan’s ability to update itself, hide its activities, and download various secondary payloads makes it particularly dangerous in today’s threat landscape.

The removal process requires a systematic approach to ensure all components are eliminated, as the trojan is designed to resist standard removal techniques. For most users, specialized anti-malware tools offer the best chance of complete removal, while advanced users may attempt manual removal with appropriate caution.

As with most malware threats, prevention remains the most effective strategy. By implementing strong security practices, including email caution, regular software updates, and robust security solutions, users can significantly reduce their risk of Smoke Loader infection and the cascade of secondary infections it typically brings.

By understanding how Smoke Loader operates and implementing the recommended security practices, you can protect your systems from this persistent and evolving threat.