*epta.mcold@gmail.com*,

This document provides a comprehensive analysis and recovery guide for the ransomware variant identified by the file extension *[email protected]*,. This variant belongs to the prolific STOP/Djvu ransomware family, known for its widespread distribution and continuous evolution.

Technical Breakdown:

1. File Extension & Renaming Patterns

Confirmation of File Extension: Files encrypted by this ransomware variant will have the string [email protected] appended to their original filenames. For example, a file originally named document.docx would become [email protected].
Renaming Convention: The typical renaming pattern for STOP/Djvu variants, including this one, is:
[Original Filename].[Original Extension].[Random 4-character ID][email protected]
Note: While some Djvu variants append a unique ID before the variant specific extension, the provided string [email protected] suggests that the entire string is appended directly after the original filename, possibly with a unique victim ID generated internally but not explicitly visible in the filename itself, or the ID is integrated uniquely. The [email protected] component typically serves as a contact email for the attackers, found within the ransom note.
Ransom Note: Upon encryption, the ransomware drops a ransom note file named _readme.txt in every folder containing encrypted files. This note contains instructions on how to contact the attackers (usually via the provided email [email protected]), the ransom amount (typically between $490 and $980 USD), and payment methods (usually cryptocurrency like Bitcoin).

2. Detection & Outbreak Timeline

Approximate Start Date/Period: The STOP/Djvu ransomware family has been active since late 2017/early 2018, with new variants continually emerging. The .epta variant, specifically associated with the [email protected] contact, is a more recent iteration within this long-running family, likely emerging in late 2023 or early 2024, following the trend of new Djvu variants appearing almost weekly or monthly. Its widespread propagation began shortly after its initial compile date.

3. Primary Attack Vectors

The *[email protected]* variant, like other STOP/Djvu ransomware, primarily relies on social engineering and deceptive distribution methods rather than exploiting network vulnerabilities:

Compromised Software Downloads: This is the most prevalent vector. Victims often get infected by downloading cracked software, pirated games, “free” software activators (e.g., KMS activators), keygens, or other illicit software from dubious websites, torrents, or unofficial download portals. The ransomware is often bundled within these executables.
Malvertising & Deceptive Websites: Malicious advertisements or redirecting users to compromised websites that push fake software updates, deceptive installers, or direct malicious downloads are also common.
Phishing Campaigns: While less common as a direct initial infection vector for STOP/Djvu (compared to email-borne macro malware), phishing emails can sometimes lead users to download malicious attachments or visit deceptive websites that then deliver the ransomware payload.
Remote Desktop Protocol (RDP) Exploits: While not a primary initial infection vector for Djvu, compromised RDP credentials can be used by attackers to gain access to a system and manually deploy the ransomware. This is more typical for targeted attacks than the broad distribution seen with Djvu.
Software Vulnerabilities: Generally not a primary vector for initial infection with Djvu/STOP ransomware. This family relies more on user execution of seemingly legitimate but malicious files rather than zero-day or N-day exploits for initial compromise (e.g., EternalBlue, SMBv1 are not typical for this family).

Remediation & Recovery Strategies:

1. Prevention

Proactive measures are crucial to prevent infection by *[email protected]*, and other ransomware variants:

Regular Backups: Implement a robust backup strategy following the 3-2-1 rule (3 copies of data, 2 different media, 1 offsite/cloud). Ensure backups are isolated from the network to prevent encryption.
Robust Antivirus/Anti-malware: Use a reputable, up-to-date antivirus suite with real-time protection and behavioral detection capabilities.
Software Updates & Patching: Keep your operating system (Windows, macOS, Linux) and all installed software (web browsers, productivity suites, media players, etc.) updated with the latest security patches.
Email Vigilance: Be cautious of unsolicited emails, especially those with attachments or links. Verify the sender and content before clicking or opening anything.
Avoid Pirated/Cracked Software: Never download or execute software from unofficial sources, torrents, or websites offering cracks, keygens, or pirated content. This is the single most common infection vector for STOP/Djvu.
Ad-Blockers: Use browser extensions to block malicious advertisements (malvertising).
Network Segmentation: For organizations, segment your network to limit the lateral movement of ransomware in case of an infection.
Strong Passwords & MFA: Use strong, unique passwords for all accounts and enable Multi-Factor Authentication (MFA) wherever possible.
User Education: Educate users about phishing, social engineering tactics, and the risks associated with downloading untrusted software.
Disable Macros by Default: Configure Microsoft Office to disable macros by default or only allow digitally signed macros from trusted publishers.
Disable VSS/Shadow Copies Access (for non-critical users): While ransomware often deletes them, limiting VSS access can sometimes prevent quick deletion.

2. Removal

If your system is infected, follow these steps for cleanup:

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 Stop Malicious Processes: Use Task Manager (Windows) to identify any suspicious processes consuming high CPU/memory or having unusual names. Terminate them if confident, but proceed with caution.
3. Scan and Remove with Antivirus/Anti-malware: Boot the system into Safe Mode with Networking (if possible) or use a bootable antivirus rescue disk. Run a full system scan with your updated antivirus and a reputable anti-malware tool (e.g., Malwarebytes, Emsisoft Anti-Malware). Allow them to quarantine or remove detected threats.
4. Check Startup Entries & Scheduled Tasks: The ransomware often establishes persistence. Check Windows startup folders, registry keys (e.g., HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run), and Task Scheduler for suspicious entries and disable/delete them.
5. Remove Ransom Note: Delete all _readme.txt files found on your system after the ransomware payload has been removed.
6. Professional Help: If you are unsure or uncomfortable with these steps, seek assistance from a cybersecurity professional. Avoid immediate system reinstallation if you hope to recover files, as this might destroy evidence or original encrypted files needed for decryption attempts.

3. File Decryption & Recovery

Recovery Feasibility: The feasibility of decrypting files encrypted by *[email protected]*, is variable and depends on whether an “offline” or “online” encryption key was used.
- Online Key: If the victim’s computer had an active internet connection during encryption, the ransomware generates a unique “online key” from a remote server for each victim. Decryption without the attacker’s key (or a discovered vulnerability/flaw) is currently impossible.
- Offline Key: If the victim’s computer was offline during encryption, the ransomware uses a pre-defined “offline key.” There’s a chance that this offline key has been recovered or released by cybersecurity researchers.
Decryption Tools:
- Emsisoft Decryptor for STOP/Djvu Ransomware: This is the primary tool for attempting decryption. You can download it from the Emsisoft website.
  - How it works: The decryptor attempts to match your encrypted files with known online or offline keys. You will need one original encrypted file and its unencrypted version (if available) to help the tool identify the specific key used.
  - Limitations: It can only decrypt files encrypted with a known online key or if an offline key was used and is already cracked/released. If a unique online key was used that isn’t publicly available, the tool will indicate it cannot decrypt your files.
- Paying the Ransom: This is strongly discouraged. There is no guarantee that paying the ransom will result in receiving a working decryption key. It also funds criminal activities and encourages further attacks.
Other Recovery Methods (Limited Success):
- System Restore & Shadow Volume Copies (VSS): STOP/Djvu ransomware typically deletes Shadow Volume Copies using vssadmin.exe Delete Shadows /All /Quiet. Therefore, relying on these for recovery is usually futile.
- File Recovery Software: Data recovery tools (e.g., PhotoRec, Recuva) might occasionally recover deleted original files if the ransomware copied, encrypted, and then deleted the originals, and if no new data has overwritten them. However, this is rarely effective for widespread recovery.
- Backups: The most reliable method of file recovery is restoring from clean, isolated backups.

4. Other Critical Information

Ransom Note Consistency: The _readme.txt ransom note is a hallmark of the STOP/Djvu family. Always check its content for the exact email address specified (e.g., [email protected]) and any unique IDs, as these details can sometimes help identify the precise variant.
Hosts File Modification: This ransomware often modifies the Windows hosts file (C:\Windows\System32\drivers\etc\hosts) to block access to security-related websites (antivirus vendors, cybersecurity blogs) to hinder recovery efforts. Always check and restore your hosts file to default.
Disabling Windows Defender: It might also attempt to disable Windows Defender or other security software.
Prevalence: The STOP/Djvu family, including the *[email protected]* variant, is one of the most widespread ransomware threats, primarily targeting home users and small businesses due to its reliance on deceptive software downloads. Its continuous evolution means new variants appear frequently, often with minor changes to the file extension or contact email.
Broader Impact: The broad distribution of STOP/Djvu ransomware leads to significant financial losses for individuals and small businesses who either pay the ransom or lose irreplaceable data. The psychological impact on victims is also substantial. Its simple, effective distribution method ensures it remains a persistent threat in the cybersecurity landscape.