*****.***@***.sophos

[Content by Gemini 2.5]

This document provides a comprehensive analysis and actionable strategies for dealing with the ransomware variant identified by the file extension *****.***@***.sophos. This variant is a derivative of the well-known Dharma ransomware family (also known as CrySiS, Brrr, Dharma/Gop), characterized by its distinctive file renaming pattern and reliance on email communication for ransom demands.

Important Note: The use of “sophos” in the file extension and email pattern is a tactic by the threat actors to identify their variant or campaign. It is not affiliated with or related to the legitimate cybersecurity company Sophos.

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension:
    The exact file extension used by this specific Dharma variant is .sophos. This means encrypted files will have this string appended as the final part of their name.

  • Renaming Convention:
    The typical file renaming pattern employed by this ransomware is:
    [original_filename].[original_extension].id-[ID_string].[email_address].sophos

    • [original_filename]: The name of the original file.
    • [original_extension]: The original extension of the file (e.g., .docx, .jpg, .pdf).
    • id-[ID_string]: A unique alphanumeric identifier specific to the victim’s infection.
    • [email_address]: An email address provided by the attacker for contact. Based on the given pattern, this email address is expected to end with @***.sophos (e.g., [email protected], [email protected]).
    • .sophos: The final, unique extension appended by this specific Dharma variant.

    Example: A file named document.docx might be renamed to document.docx.id-A1B2C3D4.[[email protected]].sophos or document.id-A1B2C3D4.[[email protected]].sophos (sometimes the original extension is dropped if the ransomware appends its own before the email).

    Additionally, a ransom note will be dropped in encrypted directories, typically named info.txt or FILES ENCRYPTED.txt, and sometimes also as an .hta file (e.g., info.hta). These notes contain instructions on how to contact the attackers and demand payment.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period:
    The Dharma ransomware family has been continuously active and evolving since late 2016. New variants, often distinguished by their unique appended file extensions or contact emails, emerge frequently. This particular .sophos variant is part of these ongoing campaigns, indicating its emergence within the broader Dharma activity, likely in the past year or two as a distinct iteration. Dharma remains a persistent threat, with new “brands” appearing regularly.

3. Primary Attack Vectors

Dharma ransomware, including the .sophos variant, primarily leverages the following propagation mechanisms:

  • Remote Desktop Protocol (RDP) Exploits: This is the most common attack vector. Threat actors scan the internet for RDP ports that are exposed (often port 3389). They then attempt to gain access through:

    • Brute-force attacks: Systematically trying common or guessed username/password combinations.
    • Weak/Stolen Credentials: Exploiting instances where RDP is secured with weak passwords or where credentials have been compromised in previous data breaches and are being reused.
    • Unpatched RDP Vulnerabilities: Less common for Dharma specifically, but possible if severe vulnerabilities are known and exploitable.

  • Phishing Campaigns: Malicious emails are used to deliver the ransomware payload. This can involve:

    • Malicious Attachments: Email attachments (e.g., seemingly legitimate documents, invoices, or reports) containing embedded macros, scripts, or executable files that, when opened, download and execute the ransomware.
    • Malicious Links: Links within emails that redirect users to compromised websites hosting the ransomware or to phishing pages designed to steal credentials.

  • Software Vulnerabilities: While RDP and phishing are primary, initial access can sometimes be gained through:

    • Exploitation of Vulnerabilities in Public-Facing Applications: Weaknesses in web servers, VPNs, or other internet-exposed services could be exploited to establish a foothold on the network.
    • Compromised Software Downloads/Cracked Software: Users downloading pirated software, crack tools, or software from untrusted sources may inadvertently execute the ransomware.

Remediation & Recovery Strategies:

1. Prevention

Proactive measures are crucial to defend against .sophos ransomware and similar threats:

  • Strong RDP Security:

    • Limit RDP Exposure: Do not expose RDP directly to the internet. Use a Virtual Private Network (VPN) for remote access.
    • Multi-Factor Authentication (MFA): Implement MFA for all RDP access.
    • Strong, Unique Passwords: Enforce complex, unique passwords for all user accounts, especially those with RDP access.
    • Account Lockout Policies: Configure account lockout policies to thwart brute-force attempts.
    • Network Level Authentication (NLA): Enable NLA for RDP connections.
    • Dedicated Admin Accounts: Use separate, non-privileged accounts for daily work and only use administrator accounts when absolutely necessary.

  • Robust Email Security:

    • Email Filtering & Sandboxing: Implement advanced email filtering solutions that can detect and quarantine malicious attachments and links.
    • User Awareness Training: Regularly train employees to recognize and report phishing attempts.
    • Spam Filters & DNS Records: Utilize SPF, DKIM, and DMARC to prevent email spoofing.

  • Regular Backups (3-2-1 Rule):

    • Maintain at least three copies of your data, on two different media, with one copy offsite or offline (air-gapped). Test your backups regularly to ensure recoverability.

  • Endpoint Detection and Response (EDR) / Antivirus:

    • Deploy and maintain next-generation antivirus/EDR solutions on all endpoints and servers. Ensure they are updated frequently.

  • Patch Management:

    • Keep operating systems, applications, and network devices fully patched and up-to-date to mitigate known vulnerabilities.

  • Network Segmentation:

    • Isolate critical systems and sensitive data from the broader network to limit lateral movement in case of a breach.

  • Principle of Least Privilege:

    • Grant users and applications only the minimum necessary permissions to perform their functions.

2. Removal

If infected, follow these steps to effectively remove .sophos ransomware:

  1. Immediate Isolation: Disconnect the infected system(s) from the network (unplug network cables, disable Wi-Fi) to prevent further spread.
  2. Identify & Quarantining:
    • Use a reputable anti-malware solution (e.g., Sophos Intercept X, Kaspersky, ESET, Bitdefender, Malwarebytes) to scan the system thoroughly.
    • Ensure the anti-malware software is updated with the latest definitions.
    • Quarantine or delete all detected ransomware components and associated files.
  3. Check for Persistence: Ransomware often establishes persistence mechanisms (e.g., registry run keys, scheduled tasks, startup folders). Manually inspect these areas or use specialized tools to remove any lingering components.
  4. Change Credentials: Assume all credentials on the infected system or network segment are compromised. Change all passwords, especially for administrative accounts, email, and RDP.
  5. Forensic Analysis (Optional but Recommended): If possible, engage cybersecurity professionals to conduct a forensic analysis to understand the initial attack vector, extent of compromise, and any data exfiltration.
  6. Rebuild/Restore: The most secure method is often to wipe the infected system and restore it from clean backups.

3. File Decryption & Recovery

  • Recovery Feasibility:
    Unfortunately, for most recent Dharma ransomware variants, including the .sophos one, decryption without the private key from the attackers is generally not possible. There are no publicly available universal decryptors that work for all Dharma versions, especially newer ones. While some older Dharma variants had decryptors released by security researchers (often leveraging flaws in the ransomware’s implementation), these are usually ineffective against new versions.

    It is strongly advised against paying the ransom. There is no guarantee that attackers will provide the decryption key, and paying emboldens criminal activity.

  • Essential Tools/Patches:

    • Data Backups: This is the most critical tool for recovery. Restore from secure, recent, and offline/air-gapped backups.
    • Reputable Anti-Malware Software: Crucial for both prevention and removal. Keep it updated.
    • Patch Management System: To ensure all software and OS are up-to-date.
    • RDP Hardening Tools/Best Practices: To secure remote access points.
    • Network Monitoring Tools: To detect suspicious activity indicative of RDP brute-forcing or lateral movement.
    • File Recovery Software (Limited Use): In some rare cases, if only part of a file was encrypted or shadow copies were not fully deleted, tools like ShadowExplorer or Recuva might recover older versions, but this is unlikely for full Dharma encryption.

4. Other Critical Information

  • Additional Precautions/Characteristics:

    • Shadow Copy Deletion: Like many ransomware variants, .sophos Dharma will attempt to delete Volume Shadow Copies (VSS) to prevent easy recovery from local backups.
    • Security Software Disabling: It may try to disable or interfere with endpoint security solutions.
    • Ransom Notes: Typically, .txt and .hta files are dropped, containing the ransom demand, contact email, and unique ID. The .hta file often presents a GUI window with the ransom message.
    • Wide File Type Targeting: It targets a vast array of file types (documents, images, videos, databases, archives, etc.) across local drives and accessible network shares.

  • Broader Impact:

    • Significant Data Loss: The primary impact is the loss of access to critical data, which can halt business operations.
    • Operational Disruption: Recovery efforts can be lengthy, leading to prolonged downtime and lost productivity.
    • Financial Costs: Besides the potential ransom (which should be avoided), there are significant costs associated with incident response, forensic analysis, system rebuilding, and reputational damage.
    • Targeting SMBs: Dharma frequently targets small to medium-sized businesses due to their often weaker security postures and less mature incident response capabilities.
    • Ongoing Threat: The Dharma family’s continuous evolution and varied branding mean organizations must maintain vigilance and adapt their defenses.

By understanding the technical aspects and implementing robust prevention and recovery strategies, individuals and organizations can significantly mitigate the risk posed by the .sophos Dharma ransomware variant.