@locked

[Content by Gemini 2.5]

The file extension @locked is commonly associated with variants of the Phobos ransomware family. Phobos is a persistent and highly disruptive ransomware, known for its focus on encrypting critical data for ransom. This resource provides a comprehensive breakdown of its characteristics and strategies for prevention, remediation, and recovery.

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: The exact file extension used by this ransomware variant is generally appended as .locked (e.g., filename.docx.locked). However, it’s crucial to note that Phobos variants often use a more complex, structured extension pattern, where locked is the final part.
  • Renaming Convention: Files encrypted by Phobos (and thus those ending in .locked) typically follow a pattern that includes a unique victim ID and sometimes contact information or a specific identifier before the final extension. The common renaming convention is:
    [original_filename].id[victim_ID].[email_or_unique_identifier].locked
    • Example: A file named document.pdf might be renamed to document.pdf.id[A1B2C3D4].[[email protected]].locked or document.pdf.id[A1B2C3D4].data_manager.locked.
      The id string and the unique identifier are specific to each infection and often serve as a unique key for the attackers to identify the victim.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: The Phobos ransomware family, from which @locked variants derive, first emerged around late 2017 or early 2018. It quickly gained notoriety and has been consistently active ever since, with new variants and minor modifications appearing regularly. It has maintained a steady presence as a significant threat in the ransomware landscape for several years.

3. Primary Attack Vectors

Phobos ransomware, including the variants using the @locked extension, primarily relies on the following propagation mechanisms:

  • Remote Desktop Protocol (RDP) Exploitation: This is one of the most common and successful methods. Attackers often brute-force weak RDP credentials or exploit vulnerabilities in RDP services to gain initial access to systems. Once inside, they manually deploy the ransomware.
  • Phishing Campaigns: Malicious emails containing infected attachments (e.g., seemingly legitimate documents with embedded macros) or links to malicious websites are frequently used. If opened or clicked, these payloads can download and execute the ransomware.
  • Software Cracks and Pirated Software: Phobos is often bundled with unofficial software activators, key generators, or pirated applications downloaded from untrusted sources. Users who install these applications unknowingly execute the ransomware alongside the desired software.
  • Exploitation of Software Vulnerabilities: While less common than RDP, Phobos operators may leverage known vulnerabilities in public-facing services (e.g., unpatched servers, VPN services, or web applications) to gain initial access and deploy the ransomware.
  • Malicious Websites/Drive-by Downloads: Visiting compromised or malicious websites can sometimes trigger drive-by downloads, leading to the silent execution of the ransomware or other malware that then deploys Phobos.

Remediation & Recovery Strategies:

1. Prevention

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

  • Robust Backup Strategy: Implement a 3-2-1 backup rule (3 copies of data, on 2 different media, with 1 off-site/offline). Regularly test your backups to ensure data integrity and recoverability. Off-site or immutable backups are crucial to prevent ransomware from encrypting your backups.
  • Strong Password Policies & Multi-Factor Authentication (MFA): Enforce complex, unique passwords for all accounts, especially those with administrative privileges or RDP access. Implement MFA wherever possible, particularly for VPNs, RDP gateways, and critical internal systems.
  • Patch Management: Keep operating systems, software, and firmware up-to-date with the latest security patches. Prioritize patching known vulnerabilities, especially for public-facing services.
  • Network Segmentation: Isolate critical systems and sensitive data from the rest of the network. This limits the lateral movement of ransomware if an initial breach occurs.
  • Endpoint Detection and Response (EDR) / Antivirus Solutions: Deploy and regularly update reputable EDR or next-generation antivirus software across all endpoints and servers. Configure them to perform real-time scanning and behavioral analysis.
  • User Training & Awareness: Educate employees about phishing, social engineering tactics, and the dangers of opening suspicious attachments or clicking on dubious links.
  • Disable/Secure RDP: If RDP is not essential, disable it. If required, restrict access to specific IP addresses, use strong passwords, MFA, and place RDP behind a VPN. Monitor RDP logs for unusual activity.

2. Removal

Removing the @locked ransomware from an infected system is critical to prevent further damage. This typically involves:

  • Isolate the Infected System: Immediately disconnect the infected computer from the network (physically or by disabling network adapters). This prevents the ransomware from spreading to other systems or shared drives.
  • Identify & Kill Malicious Processes: Use Task Manager or Process Explorer to identify and terminate any suspicious processes. Phobos may masquerade as legitimate system processes.
  • Full System Scan with Anti-Malware: Boot the system into Safe Mode with Networking (if necessary) and run a full, deep scan using a reputable and updated anti-malware solution (e.g., Windows Defender, Malwarebytes, Sophos, CrowdStrike, etc.). Ensure the anti-malware tool is capable of detecting and removing ransomware remnants.
  • Check for Persistence Mechanisms: Phobos may establish persistence to re-launch after reboot. Manually check common persistence locations such as:
    • Registry Run keys (HKCU\Software\Microsoft\Windows\CurrentVersion\Run, HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run)
    • Startup folders (%APPDATA%\Microsoft\Windows\Start Menu\Programs\Startup)
    • Scheduled Tasks (schtasks /query)
    • WMI subscriptions
    • Remove any suspicious entries related to the ransomware.
  • Remove Dropped Files: Delete any suspicious executable files or ransom notes (e.g., info.hta, info.txt) left by the ransomware.
  • Change All Passwords: After confirming the system is clean, change all passwords, especially for administrative accounts and any accounts that might have been compromised or accessible from the infected machine.

3. File Decryption & Recovery

  • Recovery Feasibility: As of the current knowledge base, there is no public or universally effective decryption tool available for files encrypted by Phobos ransomware variants, including those using the @locked extension, without obtaining the private key from the attackers. This means that direct decryption of encrypted files is generally not possible.
  • Recommended Recovery Method: The primary and most reliable method for recovering data encrypted by @locked is to restore from clean, uninfected backups.
    • Ensure that the backup source is isolated from the network during the infection to prevent it from being encrypted as well.
    • If Shadow Volume Copies (VSS) were enabled, the ransomware often attempts to delete them (vssadmin delete shadows /all /quiet). However, it’s always worth attempting recovery from shadow copies if backups are unavailable, though success is often limited for Phobos.
  • Essential Tools/Patches:
    • Robust Backup Solutions: Cloud-based, off-site, or immutable storage solutions are crucial.
    • Up-to-date Operating System and Software: Regular patching of Windows and other applications closes vulnerabilities.
    • Security Software: A combination of antivirus/EDR, firewalls, and network intrusion detection/prevention systems.
    • Forensic Tools: For incident response, tools like Autoruns, Process Explorer, and network analysis tools can help identify the infection vector and extent of compromise.

4. Other Critical Information

  • Additional Precautions:
    • Ransom Notes: @locked ransomware typically drops ransom notes named info.hta (an HTML application that displays the ransom message in a graphical window) and info.txt (a plain text file). These notes contain instructions on how to contact the attackers (usually via email) to pay the ransom in cryptocurrency.
    • Shadow Copy Deletion: Like many modern ransomware variants, Phobos specifically targets and attempts to delete Shadow Volume Copies to hinder recovery efforts by victims.
    • “Do Not Pay” Stance: Cybersecurity experts and law enforcement generally advise against paying the ransom. Paying encourages further ransomware attacks, funds criminal activities, and does not guarantee decryption or the safe return of data. There’s a risk of being extorted further or receiving a non-functional decryptor.
  • Broader Impact:
    • Significant Business Disruption: Phobos infections can lead to prolonged operational downtime for organizations, impacting productivity, customer service, and supply chains.
    • Financial Loss: Beyond the potential ransom payment (if chosen, though not recommended), organizations face costs associated with incident response, system reconstruction, data recovery, potential fines (e.g., GDPR, HIPAA), and lost revenue during downtime.
    • Reputational Damage: An attack can severely damage an organization’s reputation, eroding customer trust and stakeholder confidence, especially if sensitive data is compromised or services are unavailable for extended periods.
    • Potential Data Exfiltration: While Phobos’s primary modus operandi is encryption, modern ransomware groups increasingly combine encryption with data exfiltration (stealing data before encrypting it). Although not a primary feature of older Phobos variants, newer strains or associated threat actors might engage in this “double extortion” tactic, adding the threat of data leakage to pressure victims into paying.
    • Resource Drain: Responding to and recovering from a @locked infection consumes significant IT resources, diverting staff from core business functions.