[email protected]

[Content by Gemini 2.5]

As a cybersecurity expert specializing in ransomware, I’ve compiled a detailed resource regarding the ransomware variant identified by the file extension [email protected]. This specific extension strongly indicates an infection by a variant of the Dharma ransomware family, also sometimes referred to as ‘Phobos’ in some analyses due to shared characteristics and evolution, though Dharma is the more prevalent name for these specific extensions.

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: The exact file extension used by this ransomware is [email protected]. This string is directly appended to the end of encrypted files.
  • Renaming Convention: The typical file renaming pattern it employs follows this structure:
    original_filename.extension.<unique_id>.[[email protected]][email protected]
    For example, a file named document.docx might become document.docx.ID-ABCD123.[[email protected]][email protected].
    The unique_id is a string of hexadecimal characters unique to the infected system, often corresponding to a part of the victim’s machine ID or a generated GUID. The [[email protected]] part within brackets is usually the contact email address provided by the attackers.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: The Dharma ransomware family has been active since late 2016/early 2017 and has continuously evolved. Variants using similar long, email-based extensions like [email protected] are characteristic of Dharma’s sustained campaigns throughout 2018, 2019, and into recent years. While this specific extension might have a more concentrated appearance window, the underlying family has been a persistent threat for several years. New variants appear regularly, often distinguished only by the appended email address.

3. Primary Attack Vectors

  • Propagation Mechanisms: Dharma variants, including the one using the [email protected] extension, primarily leverage the following methods to spread and infect systems:
    • Remote Desktop Protocol (RDP) Exploitation: This is the most common and significant attack vector. Attackers scan the internet for exposed RDP ports (typically 3389) that are either weakly secured with easy-to-guess passwords (brute-force attacks) or have known vulnerabilities. Once access is gained, they manually deploy the ransomware.
    • Phishing Campaigns: Malicious emails containing weaponized attachments (e.g., Word documents with macros, ZIP archives with executables) or links to malicious websites are used to trick users into executing the ransomware or a dropper.
    • Software Vulnerabilities: While less common than RDP, exploitation of unpatched vulnerabilities in public-facing applications (e.g., unpatched VPN solutions, web servers, content management systems) can provide initial access for attackers to then deploy Dharma.
    • Supply Chain Attacks: In some instances, compromised legitimate software updates or third-party tools could be leveraged, although this is less typical for the broad deployment patterns of Dharma.
    • Compromised Credentials: Stolen credentials, obtained through infostealers, breaches, or dark web markets, can be used to gain unauthorized access to networks, subsequently deploying the ransomware.

Remediation & Recovery Strategies:

1. Prevention

  • Proactive Measures:
    • Secure RDP:
      • Disable RDP if not strictly necessary.
      • If RDP is required, restrict access to specific IP addresses (IP whitelisting).
      • Use strong, complex, and unique passwords for RDP accounts.
      • Implement Multi-Factor Authentication (MFA) for all RDP access.
      • Change the default RDP port (3389) to a non-standard port.
      • Use a VPN for RDP access instead of direct exposure to the internet.
    • Patch Management: Regularly update operating systems, software, and firmware to patch known vulnerabilities that attackers could exploit. Prioritize critical security updates.
    • Strong Passwords & MFA: Enforce strong, unique passwords across all accounts and implement MFA wherever possible, especially for administrative accounts and critical services.
    • Network Segmentation: Segment networks to limit lateral movement of ransomware in case of an infection.
    • Endpoint Detection and Response (EDR)/Antivirus: Deploy reputable EDR solutions and keep antivirus software updated with the latest definitions.
    • User Training: Educate employees about phishing, suspicious attachments, and safe browsing habits.
    • Backup Strategy: Implement a robust 3-2-1 backup strategy: at least 3 copies of your data, stored on 2 different media types, with 1 copy off-site and/or air-gapped (offline). Test backups regularly.

2. Removal

  • Infection Cleanup:
    1. Isolate Infected Systems: Immediately disconnect infected computers from the network (unplug Ethernet cables, disable Wi-Fi). This prevents further spread to other systems.
    2. Identify & Quarantine: Use a reputable anti-malware scanner (e.g., Malwarebytes, ESET, Bitdefender, Windows Defender) to scan the isolated system thoroughly. It’s often best to perform this scan in Safe Mode with Networking to prevent the ransomware processes from interfering.
    3. Terminate Malicious Processes: Use Task Manager (Windows) or process explorers (Sysinternals Process Explorer) to identify and terminate any suspicious processes associated with the ransomware. Look for newly created processes or unusually high CPU/memory usage from unknown executables.
    4. Remove Persistence Mechanisms: Check common ransomware persistence locations:
      • Registry Run Keys: HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run and HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
      • Startup Folders: %APPDATA%\Microsoft\Windows\Start Menu\Programs\Startup
      • Scheduled Tasks: Use schtasks.exe or Task Scheduler to look for newly created tasks.
      • WMI Event Subscriptions: Less common for Dharma but worth checking in advanced scenarios.
    5. Delete Ransomware Files: Remove the ransomware executable and any related files (often dropped in %TEMP%, %APPDATA%, or random directories).
    6. Review System Logs: Check Event Viewer (Security, System, Application logs) for suspicious activity preceding the infection.
    7. Change Credentials: After ensuring the system is clean, change all passwords used on the infected system, especially administrator and service accounts, as they might have been compromised.
    8. Vulnerability Assessment: Conduct a thorough vulnerability scan of your network to identify and remediate the initial entry point.

3. File Decryption & Recovery

  • Recovery Feasibility: For Dharma variants, including [email protected], free decryption is generally NOT possible without the private key held by the attackers. Unlike some older ransomware families, current Dharma versions implement robust encryption algorithms (e.g., AES-256 for files, RSA-2048 for the AES key) that are computationally infeasible to break.
    • No Universal Decryptor: As of now, there is no public, free decryptor tool available for active Dharma variants. While some decryptors for very old Dharma versions might exist, they will not work for this variant.
    • DO NOT Pay the Ransom: Paying the ransom is strongly discouraged. There is no guarantee you will receive a decryptor, and it fuels the ransomware ecosystem.
  • Essential Tools/Patches:
    • Data Recovery from Backups: The primary and most reliable method for file recovery is to restore from clean, uninfected backups.
    • Shadow Volume Copies: While Dharma often attempts to delete Shadow Volume Copies (vssadmin delete shadows /all /quiet), sometimes it fails. You can try data recovery software (e.g., ShadowExplorer, GetDataBack) to see if any recoverable snapshots exist, but this is a long shot.
    • Data Recovery Software: Specialized data recovery software might retrieve remnants of original files from disk if they were simply marked as deleted rather than securely overwritten, but this is highly unlikely for encrypted files.
    • Microsoft RDP Patches: Ensure all systems have the latest Windows updates, including patches for RDP vulnerabilities.
    • Network Monitoring Tools: Tools for monitoring RDP brute-force attempts or unusual network traffic can help detect and prevent initial access.

4. Other Critical Information

  • Additional Precautions:
    • Ransom Note: Dharma variants typically drop a ransom note named FILES ENCRYPTED.txt (and sometimes an HTML version like info.hta or README.txt) in every encrypted folder and on the desktop. This note contains instructions for contacting the attackers via the specified email (e.g., [email protected]) to negotiate payment, often in cryptocurrency (Bitcoin).
    • Double Extortion: While Dharma historically focused purely on encryption, some modern ransomware groups engaging with Dharma may also exfiltrate data before encryption, threatening to leak it if the ransom isn’t paid. Assume data exfiltration is a possibility.
    • No Test Decryption: Attackers often offer a “free decryption” of a few small files to prove they have the key. If you are in a desperate situation and consider this, choose non-critical, small files that do not contain sensitive information.
  • Broader Impact:
    • Widespread Impact: Dharma has affected organizations of all sizes, from small businesses to large enterprises and government entities, across various sectors globally due to its reliance on common RDP vulnerabilities.
    • Economic Disruption: Infections lead to significant downtime, data loss, recovery costs, and potential reputational damage.
    • Evolutionary Threat: The consistent evolution of Dharma, with new contact emails and minor code changes, indicates an active and resilient threat actor group behind it. This makes it a persistent challenge for cybersecurity defenses.

In summary, the [email protected] ransomware is a Dharma variant. Prevention through robust RDP security and diligent patching is paramount. In the event of an infection, focus on containment, removal, and restoring from reliable backups, as free decryption is highly improbable.