2122

[Content by Gemini 2.5]

The ransomware variant identified by the file extension .2122 is a variant of the STOP/Djvu ransomware family. This family is one of the most prolific and continuously evolving strains, primarily targeting individual users and small to medium-sized businesses globally. Its simplicity in distribution and highly effective encryption mechanism make it a persistent threat.

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: The exact file extension used by this specific variant is .2122.
  • Renaming Convention: Files encrypted by this variant will typically have their original name appended with the .2122 extension.
    • Example: document.docx becomes document.docx.2122
    • Example: photo.jpg becomes photo.jpg.2122
      In addition to file renaming, the ransomware drops a ransom note file, typically named _readme.txt, in every folder containing encrypted files, and sometimes on the desktop. This note contains instructions for the victim on how to pay the ransom.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: While the STOP/Djvu ransomware family has been active since late 2017/early 2018, specific numeric extensions like .2122 indicate a newer variant within its ongoing campaign. New extensions are released regularly, sometimes daily or weekly, to evade detection and mark new versions. The .2122 extension would have appeared sometime in late 2023 or early 2024, fitting the pattern of recent numeric extensions used by the family.

3. Primary Attack Vectors

STOP/Djvu ransomware, including the .2122 variant, primarily relies on social engineering and deceptive distribution methods rather than exploiting complex network vulnerabilities.

  • Bundled Software / Software Cracks: This is the most prevalent method. Users unknowingly download and execute infected files when attempting to install pirated software, cracked games, fake software activators (e.g., KMS activators), or key generators from torrent sites, warez forums, or untrustworthy download portals. The ransomware payload is often hidden within these seemingly legitimate executable files.
  • Malicious Email Attachments & Phishing Campaigns: Although less common for STOP/Djvu than for other ransomware, malicious documents (e.g., Word, Excel files with macros) or executable files disguised as invoices, shipping notifications, or urgent updates can be used in targeted phishing campaigns.
  • Fake Software Updates: Websites promoting fake updates for popular software (e.g., Adobe Flash Player, web browsers) can serve malicious installers that contain the ransomware.
  • Malvertising: Redirects from legitimate or compromised websites to malicious advertising domains that automatically download the ransomware or trick users into doing so.
  • Drive-by Downloads: Less common, but sometimes visiting a compromised website can initiate a download of the ransomware payload without user interaction, often leveraging outdated browser or plugin vulnerabilities.
  • Remote Desktop Protocol (RDP) Exploits: While not a primary vector for STOP/Djvu, poorly secured RDP endpoints can be exploited by attackers to gain initial access, after which they manually deploy the ransomware.

Remediation & Recovery Strategies:

1. Prevention

Proactive measures are crucial to avoid infection by the .2122 variant and other ransomware:

  • 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 offline). This is the most critical defense. Test your backups regularly.
  • Software Updates & Patch Management: Keep your operating system, applications (browsers, plugins, office suites), and antivirus software up to date with the latest security patches.
  • Strong Antivirus/Endpoint Detection and Response (EDR): Use reputable security software with real-time protection and behavioral analysis capabilities. Ensure signatures are updated frequently.
  • User Education: Train users to identify phishing attempts, suspicious emails, and the dangers of downloading pirated or untrusted software. Emphasize caution with email attachments and suspicious links.
  • Network Segmentation: Isolate critical systems and sensitive data from the rest of the network to limit lateral movement in case of an infection.
  • Disable Unnecessary Services: Turn off services like SMBv1, RDP (if not needed, or secure it with strong passwords, MFA, and VPN access if required externally).
  • Principle of Least Privilege: Grant users only the minimum necessary permissions to perform their tasks.

2. Removal

If your system is infected with the .2122 ransomware:

  1. 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.
  2. Identify and Terminate Malicious Processes: Boot into Safe Mode with Networking (if possible). Use Task Manager to look for suspicious processes. However, direct termination can be challenging as the ransomware might re-launch or be protected.
  3. Run a Full System Scan: Use a reputable antivirus or anti-malware tool (e.g., Malwarebytes, HitmanPro, your enterprise AV solution) to perform a deep scan. Ensure the definitions are updated. Allow the tool to quarantine or remove detected threats.
  4. Remove Persistent Elements: Check common persistence locations like startup folders, Run registry keys, and scheduled tasks for any entries related to the ransomware. Advanced users might use tools like Autoruns from Sysinternals.
  5. Change All Passwords: After the system is clean, change all passwords used on the infected system, especially for online accounts. The ransomware often drops information-stealing malware (like RedLine Stealer or Vidar Stealer) alongside itself, which can exfiltrate credentials.

3. File Decryption & Recovery

  • Recovery Feasibility: Decrypting files encrypted by STOP/Djvu variants like .2122 is highly challenging without the private key held by the attackers.
    • Online Keys: Most modern STOP/Djvu infections use “online keys,” meaning a unique encryption key is generated for each victim and transmitted to the attacker’s server. If your internet connection was active during encryption, an online key was likely used. There is no known way to decrypt files encrypted with online keys without the attacker’s private key.
    • Offline Keys: In rare cases, if the victim’s internet connection was unavailable or blocked at the time of encryption, the ransomware might use a “default” or “offline” key. Files encrypted with an offline key might be decryptable if security researchers have previously obtained and published that specific offline key.
  • Essential Tools/Patches:
    • Emsisoft Decryptor for STOP/Djvu: This is the only legitimate tool available for decrypting files encrypted by STOP/Djvu ransomware. It works by checking a database of known online and offline keys. You will need to provide it with an encrypted file and its original, unencrypted version (if possible) to help it identify the key pair. Important Note: If the decryptor indicates “No keys were found,” “Cannot decrypt with current keys,” or states that an online key was used, decryption is not possible with current public tools.
    • Data Recovery Software: For files that were deleted (not encrypted) by the ransomware as part of its cleanup process, data recovery software (e.g., Recuva, PhotoRec) might be able to recover some data, but this is less common for ransomware that primarily encrypts.
    • Cloud Backups/External Drives: The most reliable method to restore encrypted files is from clean, uninfected backups stored on cloud services or offline external drives.

4. Other Critical Information

  • Additional Precautions:
    • Information Stealer Risk: As mentioned, STOP/Djvu variants frequently drop additional malware, most commonly information stealers like RedLine Stealer or Vidar Stealer. These stealers can exfiltrate browser history, saved passwords, cryptocurrency wallet data, and other sensitive information. Therefore, a thorough system clean-up and changing all affected passwords are paramount.
    • Fake Decryption Tools: Be extremely wary of websites or services claiming to offer guaranteed decryption for a fee or with unknown tools. Many are scams or distribute additional malware. Always verify with trusted cybersecurity sources.
    • No Payment Recommendation: Law enforcement agencies and cybersecurity experts generally advise against paying the ransom. There’s no guarantee you’ll receive the decryption key, and it fuels the ransomware ecosystem.
  • Broader Impact:
    • Individual & SMB Impact: The .2122 variant, as part of the STOP/Djvu family, disproportionately impacts individual users and small to medium-sized businesses who may lack sophisticated cybersecurity defenses and are more likely to fall victim to social engineering tactics like pirated software.
    • Financial & Data Loss: Victims face significant financial losses (ransom demands, recovery costs) and potentially irreplaceable data loss if backups are not available or are also compromised.
    • Widespread Proliferation: Due to its effective distribution via popular channels (torrent sites), new variants like .2122 contribute to the widespread and persistent threat of ransomware, making it a major cybersecurity concern globally.
    • Resource Drain: Responding to and recovering from infections drains valuable IT resources and can disrupt operations for individuals and businesses alike.