7jo22z5m

[Content by Gemini 2.5]

This document provides a comprehensive analysis of the ransomware variant identified by the file extension 7jo22z5m. This specific extension is associated with a newer variant of the prolific STOP/Djvu ransomware family, one of the most active strains targeting individual users and small businesses globally.

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: The exact file extension used by this variant is .7jo22z5m.
  • Renaming Convention: When a file is encrypted by this ransomware, its original filename is appended with the .7jo22z5m extension.
    • Example: A file named document.docx would be renamed to document.docx.7jo22z5m. Similarly, photo.jpg would become photo.jpg.7jo22z5m.
    • Alongside the encrypted files, a ransom note named _readme.txt is dropped in every folder containing encrypted files, and often on the desktop. This note contains instructions for the victim, including a unique PersonalID and contact emails for the attackers.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: The STOP/Djvu ransomware family first emerged in late 2018/early 2019 and has been continuously evolving and active ever since. Variants like 7jo22z5m represent newer iterations within this family, indicating ongoing development and release of new versions by the threat actors. The 7jo22z5m extension itself was observed in the latter half of 2023 and into 2024, signifying a relatively recent but ongoing wave of attacks.

3. Primary Attack Vectors

The 7jo22z5m variant, like other STOP/Djvu strains, primarily relies on deceptive methods to infect systems, often targeting less technically proficient users. Common propagation mechanisms include:

  • Cracked Software and Keygens: This is the most prevalent vector. Users often download pirated software, cracked versions of legitimate programs, key generators, or software activators from unofficial websites, torrents, or file-sharing platforms. These downloads are bundled with the ransomware payload.
  • Fake Software Updates: Malicious websites or pop-ups may trick users into downloading “critical updates” for popular software (e.g., Flash Player, Java, web browsers) which are, in fact, ransomware installers.
  • Malicious Downloads: Drive-by downloads from compromised or malicious websites that host seemingly legitimate content, or direct downloads of “free” software that secretly contains the ransomware.
  • Adware Bundles: The ransomware can be distributed via aggressive adware installers or other potentially unwanted programs (PUPs) that covertly install the ransomware alongside other software.
  • Deceptive Emails (Less Common): While less frequent than for other major ransomware families, some Djvu variants may occasionally spread via phishing emails containing malicious attachments (e.g., seemingly legitimate documents with embedded macros) or links to malicious download sites.
  • RDP Exploits / Vulnerabilities (Rare for Djvu): While common for enterprise-level ransomware, STOP/Djvu typically does not leverage RDP vulnerabilities or network exploitation (like EternalBlue for SMBv1) as its primary means of propagation, focusing instead on individual user compromise through social engineering and deceptive downloads.

Remediation & Recovery Strategies:

1. Prevention

Proactive measures are crucial to prevent 7jo22z5m and similar ransomware infections:

  • Regular Backups: Implement a robust backup strategy. Store critical data on external drives, cloud services, or network shares that are disconnected from your primary system when not in use. Test your backups regularly to ensure data integrity.
  • Strong Antivirus/Endpoint Protection: Install and maintain a reputable antivirus or endpoint detection and response (EDR) solution. Ensure it’s always up-to-date with the latest virus definitions.
  • Operating System & Software Updates: Keep your operating system, web browsers, and all installed software patched and up-to-date. Attackers often exploit known vulnerabilities to gain access.
  • User Education: Educate users about the risks of downloading cracked software, opening suspicious email attachments, and clicking on dubious links. Emphasize using official and legitimate sources for software downloads.
  • Firewall Configuration: Configure your firewall to block unsolicited incoming connections and restrict outbound connections to suspicious domains.
  • Disable Macros by Default: Set Microsoft Office applications to disable macros by default, with a warning to the user before enabling.
  • Software Restriction Policies/Application Whitelisting: Implement policies to prevent the execution of programs from common ransomware drop locations (e.g., Temp folders, user profiles) or only allow whitelisted applications to run.

2. Removal

If infected by 7jo22z5m, immediate and careful steps are necessary for removal:

  1. Isolate the Infected System: Disconnect the infected computer from the network (unplug Ethernet cable, disable Wi-Fi) immediately to prevent the ransomware from spreading to other devices on the network.
  2. Do NOT Pay the Ransom: Paying the ransom does not guarantee file decryption and encourages future attacks.
  3. Boot into Safe Mode: Restart your computer and boot into Safe Mode with Networking. This often prevents the ransomware’s malicious processes from fully loading.
    • (Windows 10/11: Settings > Update & Security > Recovery > Advanced startup > Restart now > Troubleshoot > Advanced options > Startup Settings > Restart > Press 5 or F5 for Safe Mode with Networking).
  4. Run a Full System Scan: Use your updated antivirus/anti-malware software to perform a thorough scan of your entire system. Reputable tools like Malwarebytes, ESET, or SpyHunter are often effective against Djvu variants. Allow the software to quarantine or remove all detected threats.
  5. Check for Persistence:
    • Startup Programs: Check Task Manager (Startup tab) or Msconfig (Startup tab for older Windows) for suspicious entries.
    • Task Scheduler: Look for scheduled tasks that could re-launch the ransomware.
    • Registry Editor (Regedit): Carefully examine HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run and HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run for unusual entries.
    • hosts file: Check C:\Windows\System32\drivers\etc\hosts for any entries that redirect security-related websites (like antivirus vendor sites) to 127.0.0.1. Remove any such entries.
  6. Delete Suspicious Files: Manually delete any suspicious files found in temporary folders (%TEMP%), user profile directories (%APPDATA%, %LOCALAPPDATA%), or the Downloads folder that might be associated with the infection.
  7. Change Passwords: Once the system is confirmed clean, change all passwords for online accounts (email, banking, social media) that you might have accessed from the infected computer, especially if you suspect an infostealer was dropped alongside the ransomware.

3. File Decryption & Recovery

  • Recovery Feasibility: For STOP/Djvu ransomware, including 7jo22z5m variants, file decryption is potentially possible, but its success heavily depends on whether the ransomware used an “offline” or “online” encryption key.
    • Offline Key: If the victim’s computer was offline or couldn’t connect to the attacker’s server during encryption, the ransomware uses a default “offline” key from its local payload. Decryption is often possible if this key has been identified and published by security researchers. These cases are usually identifiable by the PersonalID in the _readme.txt file ending with t1.
    • Online Key: If the computer was online, the ransomware generates a unique “online” key specific to that victim and sends it to the attacker’s server. Decrypting files encrypted with an online key is not possible without that specific private key, which is held by the attackers.
  • Essential Tools/Patches:
    • Emsisoft Decryptor for STOP/Djvu Ransomware: This is the primary and most reliable tool for attempting decryption. Developed by Michael Gillespie and Emsisoft, it is regularly updated with new keys as they are discovered.
      • How to use: Download the decryptor from Emsisoft’s official website. Run it and follow the instructions. You will need to provide the PersonalID from your _readme.txt file. The tool will attempt to identify the key type and, if an offline key is known, will proceed with decryption.
    • Shadow Volume Copies: While Djvu variants typically try to delete Shadow Volume Copies (VSSadmin delete shadows /all /quiet), it’s still worth checking if any remain using tools like ShadowExplorer or native Windows restore points. However, success with this method is rare for recent Djvu variants.
    • Data Recovery Software: For highly fragmented or corrupted files (which ransomware doesn’t typically cause but can happen post-infection cleanup), general data recovery software might recover older, unencrypted versions, but this is a long shot.
    • Security Patches: While not a “recovery” tool, ensuring your OS and software are fully patched is critical for preventing re-infection and mitigating future attacks.

4. Other Critical Information

  • Additional Precautions:
    • Information Stealer Component: A significant characteristic of many STOP/Djvu variants, including 7jo22z5m, is that they often drop and execute an information stealer (e.g., Azorult, Vidar, RedLine Stealer) before encryption. This means your sensitive data (browser passwords, cryptocurrency wallets, system info, session cookies) may have already been exfiltrated. Assume your credentials are compromised and change all critical passwords after cleanup.
    • hosts file Modification: The ransomware frequently modifies the Windows hosts file to block access to legitimate security websites, making it harder for victims to seek help or download antivirus tools.
    • Self-Deletion: After encryption, the ransomware often attempts to delete its own executable to hinder analysis and forensic efforts.
  • Broader Impact:
    • Prolific Consumer Threat: STOP/Djvu is one of the most prolific ransomware families targeting home users and small businesses due to its reliance on readily available cracked software and its effective social engineering tactics.
    • Financial & Data Loss: Victims face potential financial loss from attempted ransom payments (which are not advised) and significant data loss if decryption is not possible and backups are unavailable. The additional risk of data theft from the accompanying infostealer adds another layer of damage.
    • Persistent Evolution: The constant release of new extensions (like 7jo22z5m) and minor code changes by the attackers makes it a persistent cat-and-mouse game for security researchers, who continuously work to discover new offline keys and update decryption tools.