*locked

[Content by Gemini 2.5]

The file extension *locked is not definitively tied to a single, unique ransomware family. Instead, it serves as a common extension adopted by several different ransomware variants, primarily GlobeImposter and certain versions of Phobos and Dharma. This polymorphic behavior means that while the extension might be the same, the underlying code, attack vectors, and decryption feasibility can vary.

This resource will provide a generalized breakdown applicable to ransomware variants utilizing the *locked file extension, focusing on the most common characteristics associated with it.

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: Files encrypted by this class of ransomware will typically have the .locked extension appended to their original filename.
  • Renaming Convention: The common renaming pattern is original_filename.original_extension.[ID_or_email].locked.
    • [ID_or_email]: This part is highly variable.
      • It can be a unique victim ID (a string of random characters, numbers, or a combination).
      • It might include an email address for contact (e.g., .[[email protected]].locked).
      • Some variants might append an additional, specific identifier for the ransomware family before .locked (e.g., .[random_string].dharma.locked or .[random_string].phobos.locked).
    • Examples:
      • document.docx.ID12345.locked
      • [email protected]
      • spreadsheet.xlsx.AB7CDEF8.locked
      • report.pdf.id[ABCDEF].locked (if a specific ID format is used)

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: Ransomware variants using the *locked extension (primarily GlobeImposter and Phobos) have been active since mid-to-late 2017/early 2018 and continue to evolve and remain active today. There isn’t a single “outbreak” event but rather continuous campaigns by different threat actors using these ransomware strains.
    • GlobeImposter: First emerged in late 2017, frequently updated and seen in various iterations.
    • Phobos: Appeared in late 2018 and has also maintained consistent activity, often distributed via RDP.
    • Dharma: Active since 2016, also known for using a variety of extensions, including some that might incorporate “locked” within a longer string.

3. Primary Attack Vectors

The propagation mechanisms for *locked variants are typical of many contemporary ransomware families, focusing on exploiting common vulnerabilities and human error:

  • Remote Desktop Protocol (RDP) Exploitation: This is one of the most prevalent attack vectors. Threat actors scan the internet for systems with exposed RDP ports (usually 3389) and attempt to brute-force weak credentials or exploit vulnerabilities in the RDP service. Once access is gained, the ransomware is manually deployed.
  • Phishing Campaigns: Malicious emails containing infected attachments (e.g., seemingly legitimate documents with embedded macros, password-protected archives) or links to compromised websites. If opened or clicked, these payloads can initiate the infection chain.
  • Software Vulnerabilities: Exploitation of unpatched vulnerabilities in operating systems (e.g., EternalBlue, BlueKeep, SMBv1 vulnerabilities) or commonly used software (e.g., web servers, databases, VPN services) to gain initial access and lateral movement.
  • Supply Chain Attacks: Compromising a vendor or service provider to distribute ransomware through legitimate software updates or services.
  • Malvertising/Drive-by Downloads: Users visiting compromised websites or clicking on malicious advertisements can be redirected to exploit kits that silently download and execute the ransomware without user interaction.
  • Weak Credentials: Compromised user accounts, especially those with administrative privileges, obtained through credential stuffing, password spraying, or direct dictionary attacks.

Remediation & Recovery Strategies:

1. Prevention

Proactive measures are the most effective defense against *locked and most other ransomware:

  • Robust Backup Strategy (3-2-1 Rule): Maintain at least three copies of your data, stored on two different types of media, with one copy offsite or offline (air-gapped). Regularly test backup integrity and recovery procedures.
  • Strong Passwords & Multi-Factor Authentication (MFA): Enforce strong, unique passwords for all accounts. Implement MFA for all critical services, especially RDP, VPNs, email, and cloud services.
  • Regular Patch Management: Keep operating systems, software, and firmware fully updated. Prioritize patches for known vulnerabilities, especially those related to RDP, SMB, and common web applications.
  • Network Segmentation: Isolate critical systems and sensitive data from the rest of the network. This limits lateral movement if an infection occurs.
  • Endpoint Protection: Deploy next-generation antivirus (NGAV) and Endpoint Detection and Response (EDR) solutions with behavioral analysis capabilities to detect and block suspicious activity.
  • User Awareness Training: Educate employees about phishing, suspicious links, and the importance of reporting unusual activity.
  • Secure RDP:
    • Disable RDP if not strictly necessary.
    • If RDP is required, place it behind a VPN or bastion host.
    • Limit RDP access to specific IP addresses.
    • Use complex passwords and MFA.
    • Monitor RDP logs for unusual login attempts.
  • Disable Unnecessary Services: Turn off unused ports, protocols, and services to reduce the attack surface.

2. Removal

If an infection by *locked is detected, follow these steps:

  1. Isolate Infected Systems: Immediately disconnect the infected computer(s) from the network (physically or by disabling network adapters) to prevent further spread.
  2. Identify the Source:
    • Examine system logs (Event Viewer, security logs) for unusual login attempts, process creations, or network connections prior to encryption.
    • Check for newly created files in temporary directories, %APPDATA%, %TEMP%, or startup folders.
    • Look for ransomware notes (HOW_TO_DECRYPT.txt, info.txt, etc.) which often contain details or contact information.
  3. Prevent Persistence: Check common persistence locations (Registry Run keys, Scheduled Tasks, Startup folders) for suspicious entries and remove them.
  4. Use Reputable Anti-Malware: Boot the infected system into Safe Mode (with networking, if necessary, to download tools) or from a clean bootable USB/CD. Perform a full system scan using an updated, reputable anti-malware solution.
  5. Remove Identified Threats: Allow the anti-malware software to quarantine or delete the ransomware executable and any related malicious files.
  6. Change Credentials: After ensuring the system is clean, change all passwords, especially those for administrative accounts, email accounts, and any accounts used on the infected system.

3. File Decryption & Recovery

  • Recovery Feasibility:
    • General Rule: Decrypting files encrypted by *locked variants is often very challenging or impossible without the private decryption key held by the attackers. The encryption used is typically strong (e.g., AES-256 combined with RSA-2048).
    • No More Ransom! Project: Always check the No More Ransom! website. This initiative frequently releases free decryption tools for various ransomware families. Some older or specific GlobeImposter or Dharma variants might have publicly available decryptors, but this is not guaranteed for all *locked infections, especially newer ones.
    • Paying the Ransom: Cybersecurity experts strongly advise against paying the ransom. There is no guarantee that decryptors will be provided, or that they will work. Paying also encourages further ransomware attacks.
    • Data Recovery Software (Limited Use): In some rare cases, if the ransomware only partially encrypts files or deletes shadow copies imperfectly, data recovery tools might retrieve some original files. However, this is not a reliable method for mass recovery.
  • Essential Tools/Patches:
    • No More Ransom! Decryption Tools: For checking potential free decryptors.
    • Reputable Anti-malware Software: E.g., Malwarebytes, Bitdefender, ESET, Sophos, Microsoft Defender (updated).
    • Operating System Patches: Ensure Windows/Linux/macOS are fully updated. Specifically, apply patches for SMB (MS17-010 for WannaCry-like exploits), RDP (CVE-2019-0708 for BlueKeep), and other high-severity vulnerabilities.
    • Backup & Recovery Software: Solutions like Veeam, Acronis, or cloud backup services for effective data restoration.
    • System Restore Points/Shadow Copies: While ransomware often deletes these, it’s worth checking if they exist and are unencrypted as a potential recovery option.

4. Other Critical Information

  • Additional Precautions:
    • Ransom Note Analysis: The ransom note (often HOW_TO_DECRYPT.txt, info.txt, README.txt, or similar) can sometimes provide clues to the specific variant, attacker contact methods (email, Tor addresses), and demanded ransom. This information can be useful for incident responders.
    • System Process Monitoring: *locked variants often run as executable files from temporary directories or user profiles. Monitoring unusual process activity can help in early detection.
    • File Activity Monitoring: Tools that monitor file system changes can detect rapid file renaming/encryption activity, potentially allowing for early termination of the process.
    • Volume Shadow Copy Deletion: Like most ransomware, *locked variants attempt to delete Volume Shadow Copies (vssadmin delete shadows /all /quiet) to prevent easy recovery from local backups.
  • Broader Impact:
    • Significant Data Loss: The primary impact is the loss of access to critical data, which can cripple businesses and individuals.
    • Operational Disruption: Ransomware attacks lead to downtime, interrupting business operations, productivity, and service delivery.
    • Financial Costs: Enormous costs associated with recovery, IT forensics, potential ransom payment (if chosen, which is not recommended), regulatory fines for data breaches, and reputation damage.
    • Reputational Damage: Loss of customer trust and negative publicity can have long-lasting effects.
    • Psychological Toll: The stress and pressure on IT teams and affected individuals can be immense.
    • Supply Chain Risk: If an organization in a supply chain is hit, it can disrupt downstream and upstream partners.

In summary, while the *locked extension points to a known family of threats, the best defense remains a multi-layered security approach, emphasizing proactive prevention, robust backups, and a well-practiced incident response plan.