@d0glun@*

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The file extension @d0glun@* is a specific marker often associated with a variant of the STOP/Djvu ransomware family. This family is one of the most prolific consumer-grade ransomware types, constantly evolving and releasing new strains. The * in @d0glun@* typically signifies a variable component, such as a unique victim ID or a random string, making the full appended string unique per infection, but @d0glun@ serves as the core identifier.

Here’s a detailed breakdown of this ransomware variant:

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: When files are encrypted by this variant, the string @d0glun@ (often followed by a unique ID or random characters, as indicated by the asterisk in the prompt) is appended to the original file extension. For instance, a file named document.docx might become document.docx.@d0glun@ or document.docx.[unique_id].@d0glun@. The exact full appended string can vary slightly between sub-variants but will always contain the @d0glun@ identifier.
  • Renaming Convention: The typical renaming pattern follows: [original_filename].[original_extension].[unique_id].@d0glun@ (e.g., photo.jpg.123abcDEF.@d0glun@) or [original_filename].[unique_id].@d0glun@ (e.g., spreadsheet.xlsx.ghijKLM.@d0glun@). The [unique_id] component is usually an alphanumeric string unique to the victim, helping the attackers identify the victim if a ransom is paid.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: The STOP/Djvu ransomware family, to which @d0glun@* belongs, first emerged around late 2018. Since then, it has been continuously active, with new variants being released almost daily. @d0glun@ would be one of the many permutations that have appeared within this ongoing campaign. Its prevalence steadily increased throughout 2019, 2020, and continues to be a significant threat, primarily targeting individual users.

3. Primary Attack Vectors

The @d0glun@* variant, consistent with other STOP/Djvu strains, primarily relies on the following propagation mechanisms:

  • Cracked Software & Illicit Downloads: This is the most common vector. Users looking for free versions of paid software (e.g., Photoshop, Microsoft Office, video games, VPNs) often download cracked executables, key generators, or software activators from torrent sites, warez forums, or untrustworthy download portals. These executables are secretly bundled with the ransomware installer.
  • Malicious Advertisements (Malvertising): Attackers embed malicious code within online advertisements. When a user clicks on such an ad or even visits a compromised website displaying it, the ransomware payload can be delivered through drive-by downloads or social engineering tricks.
  • Fake Software Updates: Pop-ups or deceptive websites prompting users to update their browser, Flash Player, or other essential software can trick users into downloading and executing the ransomware payload.
  • Spam Campaigns (Less Common for Djvu): While less prevalent for Djvu variants compared to other ransomware families (like Locky or Emotet), some distribution can occur through phishing emails containing malicious attachments or links, though typically the initial infection vector for STOP/Djvu leans heavily towards direct downloads.
  • Compromised Websites: Legitimate websites that have been compromised can host the malicious payload, which is then downloaded by unsuspecting visitors.

Remediation & Recovery Strategies:

1. Prevention

Proactive measures are the most effective defense against @d0glun@* and similar ransomware variants:

  • Regular, Offline Backups: Implement a robust backup strategy where critical data is regularly backed up to external drives or cloud storage that are disconnected from the network after backup completes. This is the single most effective way to recover data without paying a ransom.
  • Software and Operating System Updates: Keep your operating system (Windows, macOS) and all software (browsers, antivirus, applications) up to date with the latest security patches. This closes vulnerabilities that ransomware could exploit.
  • Reputable Antivirus/Anti-Malware: Use a comprehensive, up-to-date antivirus or Endpoint Detection and Response (EDR) solution. Ensure real-time protection is enabled.
  • User Education & Awareness: Train users to be wary of suspicious emails, unsolicited attachments, and links. Crucially, educate against downloading cracked software, keygens, or activators from unofficial sources.
  • Disable Unnecessary Services: Disable services like Remote Desktop Protocol (RDP) if not absolutely needed. If RDP is required, secure it with strong, unique passwords, multi-factor authentication (MFA), and restrict access to specific IP addresses.
  • Firewall Configuration: Configure your firewall to block outbound connections to known malicious IP addresses or C2 servers.
  • Application Whitelisting: Implement application whitelisting to prevent unauthorized executables (like ransomware) from running on your system.

2. Removal

Removing @d0glun@* from an infected system is crucial to prevent further damage, but it does not decrypt files.

  • Isolate the Infected System: Immediately disconnect the infected computer from the network (unplug Ethernet cable, disable Wi-Fi). This prevents the ransomware from spreading to other devices on the network.
  • Identify and Terminate Ransomware Processes: Boot into Safe Mode (with Networking, if necessary for AV updates). Use Task Manager to identify and terminate suspicious processes. Ransomware often runs as a seemingly innocuous process.
  • Run a Full System Scan: Use a reputable, updated antivirus/anti-malware program (e.g., Malwarebytes, Windows Defender, ESET, Bitdefender) to perform a full system scan. Most modern AVs can detect and remove STOP/Djvu ransomware files and associated components.
  • Remove Persistence Mechanisms:
    • Registry Editor (regedit.exe): Check HKCU\Software\Microsoft\Windows\CurrentVersion\Run, HKLM\Software\Microsoft\Windows\CurrentVersion\Run, and similar RunOnce keys for suspicious entries pointing to the ransomware executable.
    • Task Scheduler (taskschd.msc): Look for newly created scheduled tasks designed to re-execute the ransomware.
    • Startup Folder: Check %APPDATA%\Microsoft\Windows\Start Menu\Programs\Startup and other common startup locations.
  • Delete Shadow Copies: STOP/Djvu variants typically delete Volume Shadow Copies to hinder recovery. It’s still good practice to attempt to delete them using vssadmin delete shadows /all /quiet from an elevated Command Prompt, just in case.
  • Check hosts file: The ransomware often modifies the C:\Windows\System32\drivers\etc\hosts file to block access to security-related websites (e.g., antivirus vendor sites). Inspect this file and remove any suspicious entries.

3. File Decryption & Recovery

  • Recovery Feasibility: The feasibility of decrypting files encrypted by @d0glun@* depends on the type of encryption key used:
    • Offline Keys: If the ransomware failed to connect to its Command & Control (C2) server during encryption, it might have used a hardcoded “offline key.” Files encrypted with offline keys can often be decrypted using the official Emsisoft Decryptor for STOP Djvu.
    • Online Keys: If the ransomware successfully connected to its C2 server, it generated a unique “online key” for the victim. Files encrypted with online keys cannot be decrypted by public tools. There is currently no known way to decrypt files encrypted with unique online keys without the private key from the attackers. Paying the ransom is strongly discouraged as there’s no guarantee of decryption, and it fuels future attacks.
  • Essential Tools/Patches:
    • Emsisoft Decryptor for STOP Djvu: This is the primary tool for potential decryption. Download it only from Emsisoft’s official website or No More Ransom project. The decryptor attempts to match encrypted files against known offline keys. It’s crucial to understand that even with the decryptor, it’s not guaranteed to work for all variants or all encrypted files.
    • Data Recovery Software: For unencrypted or partially encrypted files, data recovery software (e.g., Recuva, EaseUS Data Recovery) might help recover older, deleted versions of files if shadow copies or system restore points were not fully removed. This is often a long shot for encrypted files.
    • System Restore: If system restore points were enabled and not deleted by the ransomware, you might be able to revert your system to a state before infection, but this will not decrypt files already encrypted.

4. Other Critical Information

  • Additional Precautions:
    • Ransom Note: @d0glun@* will drop ransom notes, typically named _readme.txt, in every folder containing encrypted files and on the desktop. This note contains instructions for contacting the attackers, the ransom amount (usually in Bitcoin), and a deadline.
    • Info-Stealers: A critical characteristic of the STOP/Djvu family is its tendency to drop additional malware, particularly information-stealing Trojans (e.g., Vidar, Azorult, RedLine Stealer). These steal credentials, cryptocurrency wallet information, browser history, and other sensitive data. Therefore, even if you clean the ransomware, a full system wipe and reinstallation are highly recommended to ensure no other malicious components remain.
    • Hosts File Modification: As mentioned, the ransomware modifies the Windows hosts file to block access to security websites, preventing victims from easily seeking help or downloading antivirus tools.
  • Broader Impact:
    • Individual Focus: Unlike some enterprise-grade ransomware, @d0glun@* and other STOP/Djvu variants primarily target individual users and small businesses rather than large corporations. This is due to their distribution methods (cracked software) and simpler infrastructure.
    • High Volume: Despite being “consumer-grade,” the sheer volume of infections makes STOP/Djvu one of the most impactful ransomware families globally, causing significant data loss and financial distress for countless victims who lack robust backup solutions.
    • Constant Evolution: The rapid release of new variants with minor code changes makes it challenging for security researchers to develop universal decryptors, as each new key requires analysis. This constant evolution is a hallmark of the Djvu operation.

In summary, combating @d0glun@* and its kin requires a multi-layered approach focusing heavily on prevention through user education and robust backup strategies. While decryption might be possible in some cases, the likelihood of permanent data loss is high, and the presence of associated info-stealers mandates a thorough cleanup or system reinstallation.