FMLN Ransomware: Complete Guide to Decrypt .crypt Files

FMLN is a dangerous file-encrypting ransomware that targets Windows users. Once active on a system, it encrypts personal files and appends the “.crypt-[original_extension]” extension to each filename. This guide provides a comprehensive technical analysis of FMLN ransomware, including its behavioral patterns, infection vectors, and detailed removal instructions to help affected users recover from an attack.

What is FMLN Ransomware?

FMLN is a file-encrypting malware discovered by security researchers through submissions to the VirusTotal scanning service. It targets Windows systems and employs encryption techniques to render files inaccessible to users. The primary goal of this malware is to extort payment from victims in exchange for file decryption.

After encrypting files on the victim’s computer, FMLN renames them according to a specific pattern, adding “.crypt-” before the original file extension. For example, a file named “document.pdf” would be renamed to “document.crypt-pdf”, while an image “vacation.jpg” would become “vacation.crypt-jpg”. This pattern helps identify FMLN infections compared to other ransomware variants.

Threat Type:	Ransomware, Crypto Virus, Files locker
Detection Names:	Avast (Win32:Malware-gen), ESET-NOD32 (Win32/KillProc.NFI), Kaspersky (HEUR:Exploit.Multi.DrvDos.gen), Malwarebytes (Generic.Malware/Suspicious)
Encrypted File Extension:	.crypt-[original_extension]
Ransom Note:	README.txt and pop-up window
Contact Method:	Email (dharkonsk@gmail.com)
Distribution Methods:	Infected email attachments (macros), torrent websites, malicious advertisements
Potential Damage:	File encryption, data loss, privacy violations, installation of additional malware

How FMLN Ransomware Works

Understanding the infection and encryption process of FMLN ransomware provides insights into its operation and helps implement appropriate protective measures:

File Encryption Process

FMLN targets numerous file types that typically contain valuable user data. The ransomware does not discriminate between personal and business files, encrypting everything it identifies as potentially valuable. Here are the main file categories affected:

• Documents: .doc, .docx, .xls, .xlsx, .ppt, .pptx, .pdf, .rtf, .txt
• Images: .jpg, .jpeg, .png, .bmp, .gif, .tiff, .svg
• Audio/Video: .mp3, .mp4, .wav, .avi, .mov, .mkv
• Archives: .zip, .rar, .7z, .tar, .gz
• Database files: .sql, .accdb, .mdb, .dbf
• Project files: .psd, .ai, .indd, .dwg, .csv

After encryption, the files can no longer be opened with their associated applications. For example, encrypted images will appear corrupted, and documents will be unreadable.

Visual Indicators of FMLN Infection

There are several telltale signs that your system has been infected with FMLN ransomware:

• File Extensions: Files are renamed with the “.crypt-[original_extension]” pattern
• Desktop Wallpaper: Changed to display the ransom message
• Ransom Note: A README.txt file appears in affected directories
• Pop-up Window: A ransom demand appears as a pop-up message
• System Performance: May experience slowdowns during the encryption process

Ransom Note Details

The FMLN ransomware creates a ransom note in the form of a text file (README.txt) and displays a pop-up window. The message is typically written in Spanish, though some variants may include English translations. According to translations, the ransom note includes the following elements:

Technical Indicators of Compromise (IoCs)

IoC Type	Value	Notes
Encrypted File Extension	.crypt-[original_extension]	Example: document.pdf becomes document.crypt-pdf
Ransom Note	README.txt	Created in affected directories
Desktop Change	Modified wallpaper with ransom message	Used to ensure victim notices the infection
Contact Method	Email: dharkonsk@gmail.com	Communication channel with attackers
Detection Names	Avast (Win32:Malware-gen), Combo Cleaner (Gen:Variant.Zusy.535887), ESET-NOD32 (Win32/KillProc.NFI), Kaspersky (HEUR:Exploit.Multi.DrvDos.gen)	How different antivirus products identify this threat

Distribution Methods

FMLN ransomware is distributed through various infection vectors, primarily targeting average users who may not be vigilant about security practices:

• Phishing Emails: Malicious attachments disguised as invoices, shipping documents, or other business files
• Trojan Droppers: Malware that initially infects a system and then downloads the ransomware payload
• Software Cracks: Pirated software and activation tools often bundled with malware
• Malicious Advertisements: Online ads redirecting to exploit kits that deliver ransomware
• Peer-to-Peer Networks: Torrent sites and file-sharing platforms offering infected content

Steps to Remove FMLN Ransomware

If your computer has been infected with FMLN ransomware, follow these steps to remove the malware from your system:

1. Disconnect from Networks

First, disconnect your computer from all networks to prevent potential spread to other devices and stop any ongoing communication with attacker servers:

1. Physically unplug any Ethernet cables
2. Disable Wi-Fi by turning off your wireless adapter (use airplane mode in Windows)
3. If on a business network, notify your IT security team immediately

2. Boot into Safe Mode

Safe Mode restricts which files and drivers can run during startup, potentially preventing the ransomware from executing:

3. Remove FMLN Using Anti-Malware Software

To safely remove the FMLN ransomware from your system without causing further damage, we recommend using a professional anti-malware tool:

Step	Instructions
1. Download and Install	Download Trojan Killer from the official website Run the installer and follow the on-screen instructions Launch the program after installation completes
2. Perform a Full System Scan	From the main interface, click on “Full Scan” to begin a comprehensive system check The scan will examine your system for FMLN ransomware and other potential threats Wait for the scan to complete – this may take some time depending on your system
3. Review and Remove Threats	After the scan completes, review the list of detected threats Make sure all FMLN-related items are selected for removal Click “Remove Selected” to clean your system
4. Restart Your System	After the cleaning process is complete, restart your computer Some malware components can only be fully removed after a system restart

4. File Recovery Options

Unfortunately, files encrypted by FMLN ransomware cannot be decrypted without the unique decryption key held by the attackers. However, there are several approaches you can try to recover your files:

1. Restore from backups: If you have backups on an external drive, cloud storage, or other backup system, restore your files from these sources
2. Check for Shadow Copies: Windows may have created Volume Shadow Copies of your files before encryption:

   # Run as Administrator to check for shadow copies with PowerShell vssadmin list shadows   # To restore shadow copies, use the Previous Versions feature: # Right-click on a file or folder > Properties > Previous Versions

3. No More Ransom Project: Check NoMoreRansom.org to see if a decryption tool becomes available for FMLN
4. Data recovery software: Professional data recovery software might recover some deleted original files, but success rates vary

How to Protect Your Computer from Ransomware

Preventing ransomware infections is far easier than trying to recover after an attack. Implement these protective measures to minimize your risk:

Protection Method	Description
Regular Backups	Create regular backups using the 3-2-1 approach: 3 copies, on 2 different media types, with 1 copy stored offsite. Keep external backup drives disconnected when not in use.
Keep Software Updated	Regularly update your operating system, antivirus software, browsers, and all applications to patch security vulnerabilities that ransomware might exploit.
Use Strong Security Software	Install and maintain reputable antivirus/anti-malware software with real-time protection features. Consider using Trojan Killer for comprehensive protection.
Email Security Practices	Never open attachments or click links in emails from unknown senders. Be suspicious of unexpected emails, even if they appear to come from trusted sources.
Avoid Pirated Software	Never download pirated software, “cracks,” or key generators. These are frequently used to distribute malware, including ransomware.
Use Strong Passwords	Create unique, complex passwords for all accounts and consider using a password manager to keep track of them securely.
Enable Multi-Factor Authentication	Wherever possible, enable MFA to add an extra layer of security to your accounts.
Disable Macros	Disable macros in Microsoft Office applications or set them to only run from trusted sources.
Use Data Loss Prevention	Implement data loss prevention solutions that can detect and block unauthorized data encryption attempts.

Creating Data Backups

One of the most effective protections against ransomware is maintaining regular backups of your important files. Microsoft OneDrive offers Windows users an excellent option with built-in ransomware detection and file recovery features:

1. Set up folder backup: Configure OneDrive to automatically back up your Documents, Pictures, and Desktop folders
2. Enable version history: Take advantage of version history to restore files to their pre-encryption states
3. Configure ransomware protection: Use OneDrive’s built-in ransomware detection features

For optimal protection, consider a multi-layered backup approach:

• Local Backups: External drives or network attached storage (NAS)
• Cloud Storage: Services like Microsoft OneDrive, Google Drive, or specialized backup providers
• Offline Backups: Physically disconnected storage media that cannot be affected by online threats

Similar Ransomware Threats

FMLN is one of many active ransomware threats. Understanding similar threats can help you better protect your systems:

• Nanocrypt Ransomware – Similar ransomware that targets personal files with a different encryption extension
• Sarcoma Ransomware – Sophisticated file-encrypting malware with similar targeting patterns
• LockBit 4.0 Ransomware – Advanced ransomware family primarily targeting businesses and enterprise systems

Frequently Asked Questions

How did my computer get infected with FMLN ransomware?

FMLN ransomware typically infects computers through several common vectors: phishing emails with malicious attachments, compromised websites, malicious advertisements, software cracks/pirated software, and exploit kits targeting vulnerable applications. The most frequent infection method involves users unknowingly opening malicious email attachments or downloading infected files that appear legitimate. To minimize risk, avoid opening attachments from unknown sources, keep all software updated, and use reputable security software.

Can I decrypt my files without paying the ransom?

Currently, there is no free decryption tool available for FMLN ransomware. Files can only be recovered from backups that were created before the infection occurred or potentially through Windows Shadow Copies if they weren’t deleted by the ransomware. Security experts strongly advise against paying the ransom, as there’s no guarantee you’ll receive a working decryption tool, and payment encourages further criminal activity. Instead, focus on removing the malware and restoring from backups.

Will antivirus software remove FMLN ransomware?

Yes, modern antivirus and anti-malware solutions can detect and remove the FMLN ransomware executable and its components from your system. Tools like Trojan Killer are specifically designed to identify and eliminate such threats. However, it’s important to understand that removing the malware will not decrypt your files – it will only prevent further encryption and system damage. To completely recover from an attack, you’ll need both malware removal and data restoration from backups.

What should I do immediately after discovering I’m infected with FMLN?

If you discover an FMLN infection, take these immediate steps: (1) Disconnect your computer from the internet and all networks to prevent potential spread to other devices; (2) Do not pay the ransom; (3) Boot into Safe Mode if possible; (4) Use a reputable anti-malware tool like Trojan Killer to remove the ransomware; (5) Report the attack to law enforcement through your local FBI field office or the Internet Crime Complaint Center (IC3); (6) Attempt to restore your files from backups or shadow copies; (7) If working in an organization, notify your IT security team immediately.

How is FMLN different from other ransomware?

FMLN has several distinctive characteristics compared to other ransomware families. It specifically appends the “.crypt-[original_extension]” pattern to encrypted files (e.g., “document.pdf” becomes “document.crypt-pdf”), rather than changing the entire extension. It typically communicates in Spanish in its ransom notes, though some variants include English text. FMLN also creates both a README.txt ransom note and changes the desktop wallpaper, employing multiple notification methods. While its core functionality is similar to other ransomware, these specific traits can help identify an FMLN infection versus other ransomware variants.

Conclusion

FMLN ransomware represents a significant threat to both personal and business computer users. This malicious software encrypts valuable files and demands payment for their recovery, potentially causing substantial data loss and financial harm. Understanding how this ransomware operates is crucial for both prevention and recovery.

The key to successfully managing ransomware threats lies in a proactive security approach: maintain regular, secure backups; practice careful email and download habits; keep systems and software updated; and use reputable security solutions like Trojan Killer. These measures significantly reduce both the likelihood of infection and the potential impact of an attack.

If you’ve been affected by FMLN or other ransomware, remember that paying the ransom should be considered a last resort. Instead, focus on proper malware removal and data recovery from backups, which represents a more reliable and ethical response to these cyber threats.