Trojan Floxif: Technical Analysis and Removal Guide

Trojan Floxif is a sophisticated information-stealing malware that targets Windows systems. This comprehensive guide examines Floxif’s technical characteristics, infection vectors, behavior patterns, and provides detailed removal instructions. Understanding this threat is essential for cybersecurity professionals tasked with detecting and mitigating Floxif infections within their networks.

Known Floxif Variants

Since its initial discovery, Floxif has evolved into multiple variants, each with subtle differences in functionality, infection techniques, and evasion capabilities. Security vendors use different detection names for these variants, which can sometimes cause confusion during identification and removal procedures.

Primary Variant Designations

Variant	First Observed	Notable Characteristics
Win32/Floxif.A	2016	Original variant, basic file infection capabilities
Win32/Floxif.B	2017	Added browser credential theft, improved evasion
Win32/Floxif.C	2018	Enhanced encryption for configuration data
Virus.Win32.FLOXIF.D	2019	Added lateral movement capabilities
Win32/Floxif.E	2019	Improved code cave infection techniques
Win32/Floxif.H	2020	Advanced anti-VM detection, expanded information theft

Additional Detection Signatures

Security vendors often use specialized naming conventions to indicate specific behaviors or detection methods. Common detection signatures for Floxif include:

• Win32/Floxif.E!bit – Behavior-based identification of variant E
• Win32/Floxif.gen!A – Generic detection for Floxif family
• Win32/Floxif!rfn – Detected via ransomware functionality
• Win32/Floxif!MTB – Microsoft Threat Intelligence detection
• Win32/Floxif!MSR – Microsoft Security Response detection
• Win32/Floxif.AV!MTB – Variant AV detected by Microsoft Threat Intelligence
• Floxif.AW!MTB – Variant AW detected by Microsoft Threat Intelligence
• Win32/Floxif.psyA!MTB – Polymorphic variant A detection
• Win32/Floxif.RPX!MTB – Variant with rootkit capabilities
• Win32/Floxif.RDA!MTB – Remote access variant detection

The detection of a specific variant can provide valuable information about the expected behavior, potential system impact, and appropriate removal strategies. However, it’s important to note that comprehensive scanning and removal procedures should be employed regardless of the specific variant identified, as the core infection mechanisms remain similar across the Floxif family.

Technical Analysis of Trojan Floxif

Trojan Floxif belongs to a sophisticated class of file infector malware that combines multiple attack vectors with advanced evasion techniques. Unlike many trojans that operate as standalone executables, Floxif is particularly dangerous due to its ability to inject itself into legitimate Windows executables.

File Infection Mechanism

Floxif’s core infection technique involves modifying legitimate PE (Portable Executable) files on the victim’s system:

• Code Cave Injection: Utilizes empty spaces within legitimate executables to insert malicious code without increasing file size
• Entry Point Modification: Alters the file’s entry point to execute the malicious payload before the legitimate code
• Section Injection: Adds a new section to the PE file structure to house malicious code
• Digital Signature Preservation: Advanced variants maintain the original file’s digital signature to avoid detection

This infection strategy shares similarities with older file infectors but employs more sophisticated techniques comparable to those used by Wacatac Trojan, though with a specialized focus on information theft.

Technical Characteristics

Attribute	Details
File Size	25KB to 45KB (dropper component)
File Types	Initial dropper: .exe, .scr Infected files: .exe, .dll, .ocx
Encryption	XOR-based encryption with dynamic keys for configuration data
Communication Protocol	HTTPS with custom headers, DNS tunneling (advanced variants)
Anti-Analysis Features	Anti-VM detection, sleep timers, execution process monitoring
Persistence Mechanisms	Registry modifications, infected system files, scheduled tasks
Common C2 Ports	443 (HTTPS), 53 (DNS), 8080, 8443

Behavioral Analysis

Floxif executes a multi-stage infection process that enables information theft while maintaining persistence:

1. Initial Execution: When the dropper executes, it performs system reconnaissance to identify target files and security products
2. Anti-Detection Measures: Checks for virtual machines, debugging environments, and security tools before proceeding
3. File Infection: Identifies and modifies executable files, prioritizing frequently used applications
4. System Modification: Creates persistence mechanisms through registry entries, often using run keys:

   HKCU\Software\Microsoft\Windows\CurrentVersion\Run\[random name]
   HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnce\[random name]
   HKLM\SYSTEM\CurrentControlSet\Services\[random service name]

5. Information Collection: Harvests credentials from browsers, email clients, and cryptocurrency applications
6. Data Exfiltration: Transmits collected data to command and control servers using encrypted channels

This behavioral pattern makes Floxif particularly difficult to detect using signature-based methods alone, as the malicious activity appears to originate from legitimate system processes.

Network Communication

Floxif employs sophisticated communication techniques to exfiltrate data and receive commands:

• Encrypted HTTPS Traffic: Utilizes encrypted communications to avoid network-based detection
• Domain Generation Algorithm (DGA): More advanced variants employ DGAs to dynamically create command and control domains
• DNS Tunneling: Uses DNS queries to exfiltrate data in environments with strict outbound firewall policies
• Traffic Obfuscation: Mimics legitimate web traffic patterns to blend with normal network activity

These communication patterns bear resemblance to those observed in Emotet trojan infections, though Floxif typically maintains a smaller network footprint.

Infection Vectors

Floxif spreads through multiple distribution channels, with significant evolution observed in its deployment strategies:

Primary Distribution Methods

1. Compromised Software Downloads:
   • Trojanized versions of legitimate software distributed through unofficial channels
   • Modified installers that deploy Floxif alongside legitimate applications
   • Software cracks and keygens serving as distribution vectors
2. Exploit Kits:
   • Leverages vulnerabilities in browsers and plugins (particularly Java, Flash, and outdated browser versions)
   • Uses drive-by download techniques to deliver the dropper component
   • Targets specific CVEs, including CVE-2018-8174 (Internet Explorer VBScript Engine)
3. Malicious Advertisements:
   • Malvertising campaigns that redirect to exploit landing pages
   • Fake software update prompts leading to malware downloads
   • Similar tactics to those used in fake CAPTCHA scams
4. Email-Based Distribution:
   • Malicious attachments disguised as invoices, shipping documents, or other business files
   • Embedded links to compromised websites
   • Social engineering tactics to encourage executing malicious content

Impact and Data Theft Capabilities

Floxif is primarily designed for information theft, with extensive capabilities to extract sensitive data from infected systems:

Targeted Information

• Credentials: Harvests usernames and passwords from browsers (Chrome, Firefox, Edge, Safari)
• Financial Information: Extracts banking credentials, credit card details, and cryptocurrency wallet information
• Personal Data: Collects personally identifiable information from forms and documents
• System Information: Gathers hardware configurations, installed software, and network details
• Corporate Data: Targets corporate VPN credentials and internal network access information

Secondary Payload Capabilities

In addition to information theft, some Floxif variants exhibit additional malicious capabilities:

• Secondary Payload Delivery: Can download and execute additional malware (ransomware, banking trojans)
• Lateral Movement: Advanced variants attempt to spread across network shares and removable drives
• Cryptocurrency Mining: Some versions deploy cryptominers as secondary payloads, similar to XMR64.exe cryptominer
• Remote Access: May establish backdoor functionality for remote system access

Technical Detection Methods

Detecting Floxif requires a multi-layered approach due to its file infection methodology and evasion techniques:

1. File System Indicators

Look for these suspicious file system artifacts:

# PowerShell script to scan for potentially infected files
# Note: This is a simplified example and should be expanded for production use
 
$suspiciousFiles = @()
$targetExtensions = @("*.exe", "*.dll", "*.ocx")
$targetDirectories = @("$env:SystemRoot\System32", "$env:ProgramFiles", "$env:ProgramFiles(x86)")
 
foreach ($directory in $targetDirectories) {
    foreach ($extension in $targetExtensions) {
        $files = Get-ChildItem -Path $directory -Filter $extension -Recurse -ErrorAction SilentlyContinue
         
        foreach ($file in $files) {
            try {
                # Check file properties for signs of Floxif infection
                $fileInfo = Get-Item $file.FullName
                $signature = Get-AuthenticodeSignature $file.FullName
                 
                # Look for recently modified system files or applications
                if (($signature.Status -ne "Valid") -and
                    ($fileInfo.LastWriteTime -gt (Get-Date).AddDays(-30))) {
                     
                    $suspiciousFiles += $fileInfo
                }
            }
            catch {
                # Handle exceptions
                Write-Error "Error processing $($file.FullName): $_"
            }
        }
    }
}
 
# Report suspicious files
$suspiciousFiles | Select-Object FullName, LastWriteTime

2. Memory Analysis

Floxif leaves distinctive memory patterns that can be identified through memory forensics:

// YARA rule for detecting Floxif memory patterns
rule Floxif_Memory_Pattern {
    meta:
        description = "Detects Floxif infection in memory"
        author = "Security Researcher"
        confidence = "high"
         
    strings:
        $code1 = { 56 33 F6 39 74 24 08 76 ?? 8B 44 24 04 57 8B F8 2B C6 }
        $code2 = { 83 C4 0C 84 C0 74 ?? 56 E8 ?? ?? ?? ?? 8B F0 }
        $config = { 68 ?? ?? ?? ?? E8 ?? ?? ?? ?? 83 C4 04 89 ?? ?? ?? 85 C0 }
        $str1 = "CryptCreateHash" fullword
        $str2 = "FILE_SET_ENCRYPT" fullword
        $str3 = "IsWow64Process" fullword
         
    condition:
        ($code1 or $code2) and $config and 2 of ($str*)
}

3. Network Traffic Analysis

Monitor for these network indicators:

• HTTPS connections with unusual certificate properties
• DNS queries to dynamically generated domain names
• Unexpected outbound connections from legitimate Windows processes
• Data exfiltration patterns, particularly large data transfers following user authentication activities

// Snort rule example for Floxif C2 communication
alert tcp any any -> any 443 (msg:"Possible Floxif C2 Communication"; 
    flow:established,to_server; 
    content:"|16 03 01|"; depth:3; 
    content:"|00 00 01 00|"; distance:0; within:40; 
    pcre:"/User-Agent\x3a\s+Mozilla\/5\.0\s+\(Windows\s+NT\s+\d+\.\d+\;\s+WOW64\)\s+AppleWebKit/"; 
    ssl_state:client_hello; 
    threshold:type threshold, track by_src, count 1, seconds 3600; 
    reference:url,trojan-killer.net/floxif-trojan-removal; 
    classtype:trojan-activity; sid:1000001; rev:1;)

4. Registry Indicators

Check for suspicious registry modifications:

# PowerShell script to detect suspicious registry entries
# Common Floxif registry locations
 
$registryPaths = @(
    "HKCU:\Software\Microsoft\Windows\CurrentVersion\Run",
    "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnce",
    "HKLM:\SYSTEM\CurrentControlSet\Services"
)
 
$suspiciousEntries = @()
 
foreach ($path in $registryPaths) {
    if (Test-Path $path) {
        $entries = Get-Item -Path $path | Get-ItemProperty
         
        foreach ($entry in $entries.PSObject.Properties) {
            # Skip default properties
            if ($entry.Name -match "^(PSPath|PSParentPath|PSChildName|PSDrive|PSProvider)$") {
                continue
            }
             
            if ($entry.Value -match "\.exe$" -or $entry.Value -match "%AppData%" -or $entry.Value -match "%Temp%") {
                $suspiciousEntries += [PSCustomObject]@{
                    Path = $path
                    Name = $entry.Name
                    Value = $entry.Value
                }
            }
        }
    }
}
 
# Report suspicious entries
$suspiciousEntries | Format-Table -AutoSize

Complete Floxif Removal Procedure

Removing Floxif requires a methodical approach that addresses both the dropper component and infected files. Follow these steps in sequence:

1. Preliminary Containment

1. Disconnect the infected system from networks to prevent further data exfiltration
2. Boot into Safe Mode with Networking to limit potential malware execution:

   # From Windows:
   1. Press Windows+R
   2. Type "msconfig" and press Enter
   3. Select "Boot" tab
   4. Check "Safe boot" and select "Network"
   5. Click "Apply" and "OK"
   6. Restart when prompted

2. Identify and Terminate Malicious Processes

# Use PowerShell to identify suspicious processes
Get-Process | Where-Object {
    $_.Path -and (
        $_.Path -match "\\AppData\\Local\\Temp\\" -or
        $_.Path -match "\\Temporary Internet Files\\" -or
        $_.MainWindowTitle -eq "" -and $_.Company -eq ""
    )
} | Format-Table Name, Id, Path -AutoSize
 
# Once identified, terminate processes
Stop-Process -Id [ProcessId] -Force

3. Clean Registry Persistence

Remove registry entries that enable Floxif to persist:

# Remove known Floxif registry entries
$maliciousKeys = @(
    "HKCU:\Software\Microsoft\Windows\CurrentVersion\Run\[SuspiciousKeyName]",
    "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnce\[SuspiciousKeyName]",
    "HKLM:\SYSTEM\CurrentControlSet\Services\[SuspiciousServiceName]"
)
 
foreach ($key in $maliciousKeys) {
    if (Test-Path $key) {
        Remove-Item -Path $key -Force
        Write-Host "Removed: $key"
    }
}

4. Remove Scheduled Tasks

# Identify and remove suspicious scheduled tasks
Get-ScheduledTask | Where-Object {
    $_.Actions.Execute -match "powershell|cmd|wscript" -and
    ($_.Description -eq "" -or $_.Author -eq "" -or
     $_.Actions.Arguments -match "hidden" -or
     $_.Actions.Arguments -match "encoded")
} | Unregister-ScheduledTask -Confirm:$false

5. Locate and Clean Infected Files

Addressing infected files requires specialized tools, as direct removal may damage system files. For comprehensive removal:

1. Download and install GridinSoft Anti-Malware
2. Update virus definitions to ensure detection of the latest Floxif variants
3. Run a full system scan to identify infected files
4. Allow the software to quarantine or clean infected files
5. Restart the system to complete the removal process

6. Post-Removal Verification

After cleaning, verify the system is completely free of Floxif:

1. Run a secondary scan with an alternative security tool to confirm removal
2. Check system file integrity:

   # Verify system file integrity
   sfc /scannow
   DISM /Online /Cleanup-Image /RestoreHealth

3. Monitor for suspicious network connections or unexpected system behavior
4. Verify that previously infected applications function correctly

Security Best Practices to Prevent Floxif Infections

Prevent future Floxif infections by implementing these security measures:

1. System Hardening

• Keep Windows and all applications updated with the latest security patches
• Implement application whitelisting through Windows Defender Application Control
• Enable Controlled Folder Access to prevent file tampering
• Configure User Account Control (UAC) at the highest appropriate level
• Disable unnecessary Windows services and features

2. Network Security

• Implement DNS filtering to block known malicious domains
• Enable Network Protection features in Windows Defender
• Use a hardware or software firewall with strict outbound connection controls
• Consider a network-level intrusion prevention system

3. User Education

• Avoid downloading software from unofficial sources
• Verify digital signatures of downloaded applications
• Be cautious with email attachments and embedded links
• Recognize common social engineering tactics used to distribute malware

4. Defensive Tooling

• Maintain real-time protection with a reputable security solution like GridinSoft Anti-Malware
• Implement regular system scanning and monitoring
• Consider application sandboxing for high-risk activities
• Use browser extensions that block malicious websites and scripts

Frequently Asked Questions

How does Floxif differ from other trojans?

Unlike many trojans that operate as standalone malware, Floxif’s primary distinction is its file infection capability. It modifies legitimate executables to inject its payload, making it particularly difficult to detect and remove. This approach allows it to leverage trusted applications to execute malicious code, bypass allowlist controls, and maintain persistence even after conventional malware removal. While information stealing is its primary function, similar to TrickBot, its file infection mechanism more closely resembles older virus techniques reimagined with modern evasion capabilities.

Can antivirus software detect and remove Floxif?

Most modern antivirus solutions can detect known Floxif variants, but complete removal presents challenges due to its file infection methodology. When Floxif infects legitimate system files, traditional antivirus tools may detect the infection but struggle to clean the files without damaging them. This often results in quarantine actions rather than complete remediation. Specialized anti-malware tools that understand PE file structures and can surgically remove the malicious code while preserving file functionality are typically more effective for complete Floxif removal.

What should I do if my system files are infected with Floxif?

If critical system files are infected, follow this procedure: First, create a backup of important data (avoiding executable files that might be infected). Use specialized anti-malware software like GridinSoft Anti-Malware that can clean infected files. If system files remain corrupted after cleaning, use Windows’ built-in repair tools (SFC /scannow and DISM). In severe cases where system integrity is compromised, you may need to perform a Windows repair installation or clean installation while preserving data. Always verify the integrity of any backed-up data before restoring it to the cleaned system.

How can I determine if my system is infected with Floxif?

Common indicators of Floxif infection include: unexpected system slowdowns, particularly when launching applications; modified file sizes or timestamps on executable files; unusual network connections from legitimate applications; browser redirects or search result manipulation; security tools being disabled or prevented from running; and unexpected authentication prompts or credential validation failures. For definitive detection, run a full system scan with an updated security solution and use the PowerShell detection scripts provided in this guide to identify suspicious files and registry modifications.

Does Floxif target specific industries or regions?

While Floxif can infect any Windows system, security researchers have observed targeted campaigns against financial services, healthcare organizations, and educational institutions. These targets typically have valuable data and potentially less robust security infrastructure. Geographically, significant Floxif activity has been documented in North America, Western Europe, and parts of Asia, particularly regions with high concentrations of financial services. However, unlike some advanced persistent threats with clear geopolitical motivations, Floxif campaigns appear primarily financially motivated rather than state-sponsored.

Conclusion

Trojan Floxif represents a sophisticated class of information-stealing malware that combines file infection techniques with modern evasion capabilities. Its ability to inject malicious code into legitimate executables makes it particularly challenging to detect and remove through conventional means. By understanding Floxif’s technical characteristics, infection vectors, and behavioral patterns, security professionals can better protect their systems and effectively respond to infections.

The multifaceted approach to Floxif detection and removal outlined in this guide addresses both the initial infection and its persistent components. For organizations and individuals dealing with Floxif infections, specialized tools like GridinSoft Anti-Malware provide the technical capabilities needed to effectively identify and clean infected files while preserving system integrity.

As with many evolving threats, maintaining system updates, implementing defense-in-depth security measures, and practicing safe computing habits remain the most effective ways to prevent Floxif infections and minimize their potential impact.