*[email protected]*.deniz_kizi

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This document provides a comprehensive overview of the ransomware variant identified by the file extension *[email protected]*.deniz_kizi, offering both a technical breakdown and practical recovery strategies for the community. This variant is a part of the prolific STOP/Djvu ransomware family, known for its widespread distribution and consistent evolution.

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: The exact file extension appended to encrypted files by this variant is [email protected]_kizi.
  • Renaming Convention: When a file is encrypted, the ransomware typically appends this full string to the original filename. For example, a file named document.docx would be renamed to [email protected]_kizi. The original file structure and directory paths are usually maintained, but all targeted files within accessible drives (local and sometimes network shares) will have this new extension. Alongside encryption, the ransomware also drops a ransom note, typically named _readme.txt, in every folder containing encrypted files.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: The deniz_kizi variant, as part of the STOP/Djvu family, likely emerged in late 2023 or early 2024. The broader STOP/Djvu ransomware family has been active since at least 2018 and is continually updated with new variants appearing almost weekly or monthly, making it one of the most persistent threats. Specific variants like deniz_kizi are often short-lived in their distinct naming but represent the ongoing evolution of the core ransomware. Its detection aligns with the ongoing high volume of STOP/Djvu attacks.

3. Primary Attack Vectors

*[email protected]*.deniz_kizi primarily leverages common attack vectors associated with commodity ransomware, focusing on broad distribution rather than highly targeted attacks:

  • Bundled Software/Cracked Software: This is one of the most prevalent methods. Users download pirated software, cracked applications, key generators, or fake software installers from dubious websites. The ransomware payload is often hidden within these malicious packages.
  • Fake Software Updates: Malicious websites or pop-up ads may trick users into downloading what appears to be legitimate software updates (e.g., for Adobe Flash Player, web browsers, or media players) that actually contain the ransomware.
  • Malvertising/Compromised Websites: Malicious advertisements served through legitimate ad networks or compromised legitimate websites can redirect users to landing pages that automatically download the ransomware or prompt them to download a malicious file.
  • Phishing Campaigns: While less common for initial infection compared to bundled software, basic phishing emails (e.g., fake invoices, shipping notifications, or urgent security alerts) may contain malicious attachments (scripts, executables, or documents with macros) or links leading to infected sites.
  • RDP Exploits (Less Common for this Family): While a general ransomware attack vector, STOP/Djvu variants typically don’t rely heavily on exploiting exposed Remote Desktop Protocol (RDP) ports, but it’s not impossible if a system is poorly secured and accessible.
  • Drive-by Downloads: Visiting a compromised website can sometimes initiate an automatic download of the ransomware payload without user interaction, often by exploiting vulnerabilities in web browsers or plugins.

Remediation & Recovery Strategies:

1. Prevention

Proactive measures are the most effective defense against ransomware like *[email protected]*.deniz_kizi:

  • Regular Data Backups: Implement a robust 3-2-1 backup strategy (3 copies of data, on 2 different media, with 1 copy off-site/offline). Ensure backups are immutable or regularly disconnected from the network to prevent encryption by ransomware.
  • Reputable Antivirus/Anti-Malware: Use a comprehensive, up-to-date antivirus or Endpoint Detection and Response (EDR) solution. Keep its definitions updated.
  • Operating System & Software Updates: Apply all security patches and updates for your operating system, web browsers, and all installed software promptly. This closes vulnerabilities that ransomware could exploit.
  • User Education: Train users to identify and avoid suspicious emails, malicious websites, and the risks associated with downloading pirated software or files from untrusted sources.
  • Disable Unnecessary Services: Turn off services like SMBv1, PowerShell remoting, or RDP if not explicitly needed, or secure them with strong passwords and multi-factor authentication.
  • Firewall Configuration: Implement a robust firewall to restrict inbound and outbound traffic, blocking connections to known malicious IP addresses and preventing unauthorized access.
  • Principle of Least Privilege: Limit user permissions to only what is necessary for their job functions, reducing the potential impact of an infection.

2. Removal

If an infection occurs, follow these steps to remove *[email protected]*.deniz_kizi:

  1. Isolate the Infected System: Immediately disconnect the infected computer from the network (unplug Ethernet cable, disable Wi-Fi). This prevents further spread to other devices on the network.
  2. Identify & Terminate Processes: Boot the system into Safe Mode with Networking. Use Task Manager to identify and terminate any suspicious processes. While tricky for ransomware, it can sometimes stop ongoing encryption.
  3. Run Full System Scans: Perform a full system scan using your updated antivirus/anti-malware software. It should detect and remove the ransomware executable and any associated malicious files. Consider using a reputable secondary scanner for a deeper check.
  4. Remove Persistence Mechanisms: Check common ransomware persistence locations:
    • Registry Run Keys (HKCU\Software\Microsoft\Windows\CurrentVersion\Run, HKLM\Software\Microsoft\Windows\CurrentVersion\Run)
    • Startup folders
    • Scheduled Tasks
    • Browser extensions
      Remove any entries related to the ransomware.
  5. Check for Other Malware: STOP/Djvu variants are often accompanied by information-stealing malware (e.g., Vidar, Azorult, RedLine Stealer). Run additional scans for these threats.
  6. Change All Passwords: After ensuring the system is clean, change all passwords used on the infected system, especially for online accounts, email, and banking, as information stealers may have compromised them.

3. File Decryption & Recovery

  • Recovery Feasibility: Decryption of files encrypted by *[email protected]*.deniz_kizi is challenging and often depends on the key used:
    • Online Key: If the ransomware used an “online” key (a unique key generated by the attacker’s server for each victim), decryption without the attacker’s master key is virtually impossible.
    • Offline Key: If the ransomware failed to connect to its command-and-control server and used a pre-generated “offline” key, there is a chance for recovery. Cybersecurity researchers, particularly Emsisoft, have developed a free decryptor tool for many STOP/Djvu variants. This tool attempts to decrypt files using a database of known offline keys. It’s crucial to understand that even with the Emsisoft decryptor, success is not guaranteed, especially if an online key was used.
  • Essential Tools/Patches:
    • Emsisoft Decryptor for STOP/Djvu: This is the primary tool to attempt decryption. Download it only from the official Emsisoft website or No More Ransom project.
    • System Restore Points/Shadow Copies: While many ransomware variants attempt to delete these, check if previous versions of files or system restore points exist. Use vssadmin delete shadows /all /quiet (to delete all existing shadow copies – this is not for recovery, but to prevent the ransomware from using them to revert changes) or try to restore from them if they weren’t deleted.
    • Data Recovery Software: Sometimes, data recovery software (e.g., PhotoRec, Recuva) can recover original, unencrypted files if they were simply deleted (e.g., shadow copies) rather than overwritten. Success rates vary wildly.
    • Windows Updates: Ensure the system is fully patched with the latest security updates, especially those addressing SMB vulnerabilities (like MS17-010 for EternalBlue) if the ransomware attempts network propagation.

4. Other Critical Information

  • Additional Precautions:
    • Ransom Note Consistency: Like other STOP/Djvu variants, *[email protected]*.deniz_kizi creates _readme.txt files containing the ransom demands, typically in plain text. These notes instruct the victim to contact the specified email address (e.g., [email protected]) for payment instructions, usually in Bitcoin.
    • Information Stealer Payload: A significant characteristic of many STOP/Djvu variants is the simultaneous deployment of an information-stealing Trojan (e.g., Vidar, Azorult, RedLine Stealer). This malware harvests sensitive data like browser history, saved passwords, cryptocurrency wallet information, and system details before the encryption process even begins. This means even if you recover your files, your personal information may already be compromised.
    • Shadow Copy Deletion: This ransomware aggressively attempts to delete Volume Shadow Copies to hinder recovery efforts using built-in Windows tools.
    • Do NOT Pay the Ransom: Experts strongly advise against paying the ransom. There is no guarantee that paying will result in file decryption, and it perpetuates the ransomware business model, encouraging further attacks. Instead, focus on removal, recovery from backups, and strengthening defenses.
  • Broader Impact:
    • High Volume and Accessibility: The STOP/Djvu family, including *[email protected]*.deniz_kizi, is pervasive due to its effective distribution via cracked software sites and malvertising. This makes it a common threat for individual users and smaller organizations that may lack robust cybersecurity defenses.
    • Financial and Data Loss: Victims face not only the potential loss of invaluable data but also significant financial strain if they resort to paying the ransom or incurring costs for professional data recovery. The added risk of information theft complicates matters, potentially leading to identity theft or further targeted attacks.
    • Operational Disruption: For businesses, even a single infected workstation can disrupt operations, leading to downtime, lost productivity, and reputational damage.

By understanding the technical aspects and implementing robust prevention and recovery strategies, individuals and organizations can significantly mitigate the risk posed by *[email protected]*.deniz_kizi and similar ransomware variants.