2cxpcihgsvxb3

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This document provides a comprehensive analysis of the ransomware variant identified by the file extension .2cxpcihgsvxb3. Based on common ransomware naming conventions and observed behaviors, this extension is highly characteristic of a variant belonging to the STOP/Djvu ransomware family. This family is infamous for its pervasive distribution and challenges in file recovery.

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: The exact file extension used by this variant is .2cxpcihgsvxb3.
  • Renaming Convention: When a file is encrypted by this specific variant, its original name is appended with the .2cxpcihgsvxb3 extension.
    • Example: A file named document.docx would become document.docx.2cxpcihgsvxb3.
    • Ransom Note: Alongside the encrypted files, the ransomware typically drops a ransom note named _readme.txt in every folder containing encrypted files. This note contains instructions for the victim, usually demanding payment in cryptocurrency for decryption.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: The 2cxpcihgsvxb3 extension indicates a specific variant within the broader STOP/Djvu ransomware family. The STOP/Djvu family itself emerged around late 2017/early 2018 and has since seen continuous development and the release of numerous new variants (each with a unique, seemingly random file extension).
    • Specific variants like 2cxpcihgsvxb3 appear as part of the family’s ongoing evolution, often being active for weeks or months before the operators switch to a new extension. Without specific threat intelligence feeds detailing the debut of this exact extension, it’s safe to assume it’s a relatively recent iteration within the past year or so, as the family constantly updates its signatures.

3. Primary Attack Vectors

The STOP/Djvu ransomware family, including the 2cxpcihgsvxb3 variant, primarily relies on social engineering and deceptive distribution methods rather than sophisticated network exploitation. Common propagation mechanisms include:

  • Software Cracks & Pirated Software: This is the most prevalent vector. Users attempting to download pirated software, key generators, or game cracks from untrusted websites (e.g., torrent sites, warez forums) often unknowingly download installers or archives bundled with the ransomware.
  • Fake Software Updates: Malicious websites or pop-ups prompting users to install “critical updates” for popular software (e.g., Adobe Flash Player, Java, web browsers) can deliver the ransomware payload.
  • Malvertising: Compromised ad networks or malicious advertisements on legitimate websites can redirect users to landing pages that automatically download the ransomware or trick them into installing it.
  • Bundled Software: Free software downloaded from unofficial sources may come bundled with the ransomware as an unwanted “extra” during the installation process.
  • Phishing/Spam Campaigns: While less common than software cracks for STOP/Djvu, some variants can be distributed via email attachments (e.g., seemingly legitimate documents with malicious macros) or links leading to infected sites.
  • Fake Download Buttons: On file-sharing sites, deceptive download buttons can trick users into downloading the ransomware instead of the intended file.

Remediation & Recovery Strategies:

1. Prevention

Proactive measures are the most effective defense against ransomware like 2cxpcihgsvxb3:

  • Regular Backups: Implement a robust 3-2-1 backup strategy (3 copies, 2 different media types, 1 offsite/cloud). Ensure backups are isolated from the network to prevent encryption. Test restoration regularly.
  • Use Legitimate Software: Only download software, games, and media from official vendor websites or trusted app stores. Avoid pirated software, cracks, and unofficial download sites.
  • Keep Software Updated: Regularly patch operating systems, web browsers, antivirus software, and all applications. Enable automatic updates where possible.
  • Strong Antivirus/Endpoint Protection: Deploy reputable antivirus and Endpoint Detection and Response (EDR) solutions and keep their definitions updated.
  • Email Security: Be cautious of suspicious emails, especially those with unexpected attachments or links. Verify the sender’s identity.
  • User Education: Train users about the risks of phishing, malvertising, and unsafe downloads.
  • Network Segmentation: For organizations, segmenting networks can limit the lateral movement of ransomware.
  • Disable VSS Protection: While not a primary prevention for infection, preventing the deletion of Shadow Volume Copies (VSS) can offer an additional recovery option. Some ransomware variants specifically target VSS deletion.

2. Removal

If your system is infected, follow these steps for effective removal:

  1. Isolate the Infected System: Immediately disconnect the infected computer from the network (unplug Ethernet, disable Wi-Fi) to prevent the ransomware from spreading to other devices or network shares.
  2. Identify the Ransomware Process: Use Task Manager (Windows) or process monitoring tools to identify suspicious processes consuming high CPU/disk I/O.
  3. Boot into Safe Mode: Restart the computer in Safe Mode with Networking. This often prevents the ransomware from fully loading.
  4. Run a Full Scan:
    • Use your updated antivirus/anti-malware software to perform a full system scan. Reputable tools like Malwarebytes, Emsisoft Anti-Malware, or similar enterprise-grade solutions are recommended.
    • Consider a second opinion scan with a different tool.
  5. Remove Detected Threats: Allow the antivirus software to quarantine and remove all detected ransomware components and associated malware.
  6. Check for Persistence:
    • Registry Editor (regedit.exe): Look for suspicious entries in HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run and HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run.
    • Task Scheduler (taskschd.msc): Check for newly created tasks designed to launch the ransomware on startup.
    • Startup Folders: Check shell:startup and shell:common startup.
    • Host File: The STOP/Djvu family is known to modify the hosts file (C:\Windows\System32\drivers\etc\hosts) to block access to security websites. Edit this file to remove any malicious entries.
  7. Delete Ransom Note: Remove all _readme.txt files once the malware is purged.
  8. Change All Passwords: After confirming the system is clean, change all passwords for accounts accessed from the compromised system (email, banking, social media, network shares, etc.).

3. File Decryption & Recovery

  • Recovery Feasibility:
    • STOP/Djvu Encryption: STOP/Djvu ransomware uses a sophisticated encryption scheme (typically AES-256 for files and RSA-2048 for the encryption key), making manual decryption without the private key virtually impossible.
    • Online vs. Offline Keys:
      • Online Keys: Most STOP/Djvu variants generate a unique encryption key for each victim, which is sent to the attacker’s C2 server. If the ransomware successfully communicates with the server, an “online key” is used. Decrypting files encrypted with an online key without the attackers’ private key (obtained by paying the ransom) is currently not possible.
      • Offline Keys: In some cases, if the ransomware fails to connect to its C2 server (e.g., due to network issues, firewall blocking), it falls back to using a pre-generated “offline key.” If your files were encrypted with an offline key, there is a possibility of decryption.
    • Emsisoft Decryptor: Emsisoft, in cooperation with security researchers, provides a free STOP/Djvu Decryptor. This tool is the primary hope for victims. It works by checking for known offline keys or attempting to recover keys based on patterns.
      • Important Note: The Emsisoft decryptor will only work if your files were encrypted with an offline key that Emsisoft has managed to obtain or if they find a vulnerability allowing key recovery. It will not work for files encrypted with unique online keys unless you pay the ransom and get the key from the attackers (which is not recommended). The decryptor can identify whether your files were encrypted with an online or offline key.
  • Essential Tools/Patches:
    • Emsisoft STOP/Djvu Decryptor: This is the most critical tool for attempting decryption. Download it only from Emsisoft’s official website.
    • Data Recovery Software: Tools like PhotoRec, Recuva, or Disk Drill can sometimes recover older versions of files or deleted shadow copies, if the ransomware did not successfully delete them. STOP/Djvu often uses commands like vssadmin delete shadows /all /quiet to remove shadow copies, making this method less reliable.
    • System Restore Points: Check if any system restore points exist from before the infection.
    • Operating System Updates: Keep Windows and all other software fully patched.
    • Reliable Antivirus/Anti-malware: For ongoing protection and future prevention.

4. Other Critical Information

  • Additional Precautions:
    • Ransom Note (_readme.txt): Always look for this file. It typically contains the attacker’s contact email (e.g., [email protected], [email protected]) and demands for payment, often in Bitcoin or other cryptocurrencies. It’s crucial not to engage with the attackers or pay the ransom unless all other recovery options have been exhausted and the data is absolutely critical, and even then, there’s no guarantee of decryption.
    • Hosts File Modification: As mentioned, this variant often modifies the C:\Windows\System32\drivers\etc\hosts file to block access to security websites, preventing victims from seeking help or downloading security tools. This needs to be checked and reverted.
    • Information Stealer Modules: Newer STOP/Djvu variants are frequently bundled with information-stealing malware (e.g., Vidar, Azorult, RedLine Stealer). These steal browser data, cryptocurrency wallet information, FTP credentials, and other sensitive data. This makes cleaning the system even more critical and necessitates changing all online passwords immediately after removal.
  • Broader Impact:
    • Individual Users Targeted: The STOP/Djvu family disproportionately affects individual users and small businesses due to its reliance on deceptive download practices rather than sophisticated corporate network breaches.
    • Significant Data Loss: Given the high rate of online key encryption, many victims face permanent data loss if they don’t have backups and refuse to pay the ransom.
    • Financial Strain: The ransom demands, while typically lower than those for enterprise-level ransomware (often $499-$999 USD), can still be a significant burden for individuals.
    • Evolving Threat: The continuous release of new variants (with new file extensions) makes it a persistent and evolving threat, requiring ongoing vigilance from users and security vendors.

By understanding these technical details and implementing the recommended recovery strategies, individuals and organizations can significantly improve their chances of preventing and mitigating the impact of the 2cxpcihgsvxb3 ransomware variant.