*[email protected]*

[Content by Gemini 2.5]

This detailed resource is designed to provide comprehensive information about the ransomware variant identified by the contact email *[email protected]*. While [email protected] itself is not the file extension, it is a prominent identifier found within the ransom notes of specific ransomware attacks, most notably those belonging to the Djvu/STOP ransomware family. This family is infamous for its continuous evolution and widespread impact.

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: The *[email protected]* string itself is not the file extension. Instead, it serves as a contact email address that the attackers provide in their ransom notes (typically named _readme.txt). The actual file extensions used by the Djvu/STOP variants (including those that use [email protected] in their notes) are typically 4-character random or specific strings. These extensions change frequently with each new variant released by the attackers.
    • Common Djvu/STOP Extensions (examples, not exhaustive): .djvu, .krop, .reco, .msop, .moka, .hros, .bbbw, .bopd, .lqqw, .qall, .coos, .data, and hundreds of others. When a new variant emerges, it often comes with a unique 4-character extension.
  • Renaming Convention: The ransomware encrypts files and appends its specific extension to the original filename.
    • Example: A file originally named document.docx might be renamed to document.docx.[4-char-extension], e.g., document.docx.bopd or document.docx.coos.
    • Ransom Note: A ransom note, usually named _readme.txt, is dropped in every folder containing encrypted files, as well as on the desktop. This note contains the attackers’ demands, instructions, and the [email protected] contact email (or another similar email like [email protected], [email protected], etc., depending on the specific variant and its latest contact details).

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: The Djvu/STOP ransomware family, of which variants using the [email protected] contact are a part, emerged around late 2018 / early 2019. It has been consistently active and evolving since then, with new variants being released almost daily or weekly. The specific [email protected] contact email gained prominence during various waves of these attacks, indicating a specific campaign or set of campaigns within the broader Djvu/STOP ecosystem.

3. Primary Attack Vectors

The Djvu/STOP ransomware family, including those identified by the [email protected] contact, primarily relies on social engineering and deceptive tactics rather than exploiting complex network vulnerabilities (though some variants may still attempt basic lateral movement).

  • Software Cracks/Keygens & Pirated Software: This is the most prevalent infection vector. Users download “cracked” versions of popular software (e.g., Photoshop, Microsoft Office, video games, VPNs), software activators (keygens, loaders), or pirated content from torrent sites, suspicious forums, or untrustworthy download portals. The ransomware is bundled within these seemingly legitimate but malicious files.
  • Malicious Advertisements (Malvertising): Compromised ad networks or deceptive pop-up ads can redirect users to malicious websites that trigger the download of the ransomware payload.
  • Phishing Campaigns: While less common than cracked software for Djvu/STOP, email phishing campaigns delivering malicious attachments (e.g., seemingly legitimate documents with embedded macros, or archives containing executables) can also serve as an entry point.
  • Fake Updates: Prompts for fake software updates (e.g., Flash Player, Java, browser updates) often lead to the download and execution of the ransomware.
  • Remote Desktop Protocol (RDP) Exploits (Less Common but Possible): While not the primary vector, weak RDP credentials or exposed RDP services can occasionally be exploited, allowing attackers to manually deploy the ransomware. However, this is more typical of enterprise-focused ransomware groups.
  • Bundling with Adware/PUPs: Sometimes, the ransomware payload is disguised as part of an installer for unwanted software (Potentially Unwanted Programs – PUPs) or adware, which users might inadvertently install.

Remediation & Recovery Strategies:

1. Prevention

  • Regular Data Backups: Implement a robust 3-2-1 backup strategy (3 copies of data, on 2 different media, with 1 copy off-site or air-gapped). This is the single most effective defense against ransomware.
  • Software Updates & Patching: Keep your operating system, web browsers, antivirus software, and all other applications fully updated. Patches often fix vulnerabilities that attackers could exploit.
  • Reputable Antivirus/Anti-Malware: Use a comprehensive and up-to-date antivirus/anti-malware solution with real-time protection.
  • Educate Users: Train users to identify phishing attempts, suspicious links, and untrustworthy download sources. Emphasize the dangers of pirated software and software cracks.
  • Firewall Configuration: Configure your firewall to block unauthorized inbound and outbound connections.
  • Disable RDP if Not Needed: If RDP is not essential, disable it. If required, secure it with strong, unique passwords, multi-factor authentication (MFA), and network-level authentication (NLA).
  • Application Whitelisting: Implement application whitelisting to prevent unauthorized executables (like ransomware) from running on your systems.
  • Ad Blocker/Script Blocker: Use reputable browser extensions to block malicious ads and scripts, reducing exposure to malvertising.
  • Use Standard User Accounts: Perform daily tasks from a standard user account rather than an administrator account to limit the potential damage of a ransomware infection.

2. Removal

  • Isolate 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.
  • Identify Ransomware: Note the new file extensions and the content of the _readme.txt ransom note (especially the contact email like [email protected]). This information helps in identifying the specific variant.
  • Scan and Remove:
    1. Boot into Safe Mode: This can prevent the ransomware from executing its full payload.
    2. Run Full System Scans: Use your updated antivirus/anti-malware software to perform a thorough scan and remove all detected threats, including the ransomware executable and any associated malicious files (often found in %AppData%, %Temp%, or %LocalAppdata%).
    3. Use Specialized Tools: Consider using reputable anti-malware tools that specifically target ransomware or PUPs, as Djvu/STOP often comes bundled with info-stealers like Vidar or Azorult.
  • Check for Persistent Mechanisms: The ransomware might create scheduled tasks, modify registry entries, or install unwanted software (e.g., browser hijackers, adware). Manually inspect and clean these areas if you have the expertise, or rely on comprehensive security software.
  • Change All Passwords: If an info-stealer was bundled, all credentials stored on the infected machine (browser passwords, email client passwords, etc.) might be compromised. Change passwords for all accounts accessed from the infected system, especially critical ones.

3. File Decryption & Recovery

  • Recovery Feasibility:
    • NO guaranteed decryption tool exists that works for all Djvu/STOP variants, especially for those that use online keys.
    • Emsisoft Decryptor for STOP/Djvu: Emsisoft, in collaboration with anti-malware researchers, provides a free decryptor tool for STOP/Djvu ransomware. This tool may be able to decrypt files if the ransomware used an offline key for encryption. Offline keys are used when the ransomware cannot connect to its command-and-control (C2) server. This happens less frequently with newer variants but is still a possibility.
      • How it works: The decryptor tries to match your encrypted files with a database of known decryption keys. If an offline key was used on your system, there’s a chance it’s in their database, or the decryptor can derive it if you have an original (unencrypted) version of a small file that was encrypted.
    • Important Note: If an online key was used (meaning the ransomware successfully communicated with its server to retrieve a unique encryption key for your system), then decryption without the attacker’s key is currently impossible. The Emsisoft decryptor will not work in this scenario.
  • Essential Tools/Patches:
    • Emsisoft Decryptor for STOP/Djvu: Download only from the official Emsisoft website or BleepingComputer.
    • Reputable Antivirus/Anti-Malware Software: Examples include Malwarebytes, Bitdefender, ESET, Kaspersky.
    • System Restore: If available and created before the infection, System Restore points might allow you to revert your system state, but this will not decrypt files. It can help in cleaning the system.
    • Shadow Volume Copies: Ransomware often attempts to delete Shadow Volume Copies. However, sometimes it fails, and tools like ShadowExplorer might allow you to recover previous versions of files. This is a long shot but worth checking.

4. Other Critical Information

  • Unique Characteristics ([email protected] as part of Djvu/STOP):
    • Constant Evolution: Djvu/STOP is one of the most prolific and constantly evolving ransomware families. New variants with slightly different extensions and sometimes updated code are released frequently.
    • Information Stealer Component: Many Djvu/STOP variants (especially newer ones) are bundled with info-stealers (like Vidar, Azorult, or Predator The Thief). This means that not only are your files encrypted, but your sensitive data (browser passwords, cryptocurrency wallet details, banking information, documents) might also be exfiltrated before encryption. This significantly increases the risk and impact.
    • Offline vs. Online Keys: The crucial distinction determining decryption possibility. Most newer variants try to use online keys, making decryption extremely difficult.
    • Deceptive Distribution: Its primary reliance on cracked software makes it particularly dangerous for users who engage in such activities, often leading to self-inflicted infections.
  • Broader Impact:
    • Massive Scale of Infections: Djvu/STOP has infected millions of users globally due to its effective distribution via popular pirated software channels.
    • Financial Loss: Victims face the potential loss of irreplaceable data or the difficult decision of paying the ransom (which is never guaranteed to result in decryption and funds a criminal enterprise).
    • Identity Theft/Further Compromise: The inclusion of info-stealers means victims are at higher risk of identity theft, financial fraud, and compromise of other online accounts.
    • Business Disruption: While often targeting individual users, infections can spread to small businesses or home networks, causing significant disruption and data loss.

In summary, combating *[email protected]* (or any Djvu/STOP variant) requires a multi-layered approach focusing on strong prevention, immediate isolation upon infection, and realistic expectations regarding file recovery. Paying the ransom is strongly discouraged due to the high risk and lack of guarantee.