@decrypt_2017

[Content by Gemini 2.5]

The ransomware variant identified by the file extension @decrypt_2017 is strongly associated with Sage 2.0 Ransomware, which was actively observed throughout 2017. This variant, while not as globally disruptive as WannaCry or NotPetya, was a significant threat that year, primarily spreading through sophisticated phishing campaigns.

Here is a detailed breakdown of Sage 2.0 Ransomware, using the @decrypt_2017 file extension as its identifier:

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: Encrypted files by Sage 2.0 Ransomware are appended with the extension .decrypt_2017. However, the full pattern often includes an initial @ symbol, making the specific extension .@decrypt_2017.
  • Renaming Convention: The ransomware renames files by simply appending this extension to the original filename. For example, a file named document.docx would be renamed to document.docx.@decrypt_2017.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: Sage 2.0 Ransomware was first widely detected in early 2017, specifically around January-February, and remained active throughout the year. It was a notable threat during the peak of 2017’s major ransomware campaigns.

3. Primary Attack Vectors

  • Propagation Mechanisms: Sage 2.0 primarily relied on social engineering and malicious attachments for its propagation.
    • Phishing Campaigns: The most common vector was well-crafted phishing emails. These emails typically contained:
      • Malicious JavaScript (JS) files: Disguised as invoices, shipping confirmations, or other legitimate documents, these .js files would execute upon opening, downloading and launching the ransomware payload.
      • WSF (Windows Script File) attachments: Similar to JS files, these scripts were used to fetch the ransomware executable.
      • Macro-enabled Microsoft Office Documents: Users were tricked into enabling macros, which then initiated the download and execution of the ransomware.
    • Exploitation of Remote Desktop Protocol (RDP): While less prominent for Sage 2.0 compared to its email campaigns, compromised or weakly secured RDP connections were a common entry point for many ransomware families in 2017, and it’s plausible Sage could exploit such vulnerabilities.
    • Sage 2.0 was generally not wormable, meaning it lacked the self-propagating capabilities seen in strains like WannaCry (which exploited SMB vulnerabilities like EternalBlue). Its spread was largely dependent on user interaction with malicious content.

Remediation & Recovery Strategies:

1. Prevention

  • Proactive Measures:
    • Robust Email Security: Implement advanced spam filters, attachment scanning, and sandboxing solutions to detect and block malicious emails before they reach end-users.
    • User Awareness Training: Conduct regular training for employees on identifying and reporting phishing attempts, suspicious attachments, and unusual email requests. Emphasize caution with unexpected attachments, especially those requiring macros.
    • Disable Macros by Default: Configure Microsoft Office and other productivity suites to disable macros by default, and only enable them from trusted sources.
    • Patch Management: Ensure operating systems (Windows, macOS, Linux) and all software applications (browsers, plugins, Office suites, PDF readers, etc.) are kept up-to-date with the latest security patches.
    • Antivirus and Endpoint Detection and Response (EDR): Deploy and maintain robust antivirus and EDR solutions on all endpoints and servers. Ensure they are configured for real-time scanning and regularly updated.
    • Regular, Offline Backups: Implement a comprehensive backup strategy, ensuring critical data is backed up regularly to offsite or offline storage. This is the most reliable method for data recovery from ransomware attacks.
    • Network Segmentation: Segment networks to limit lateral movement of ransomware in case of an infection.
    • Principle of Least Privilege: Restrict user permissions to only what is necessary for their roles, limiting the potential damage if an account is compromised.

2. Removal

  • Infection Cleanup:
    1. Isolate Infected Systems: Immediately disconnect any infected computers or servers from the network (physically or by disabling network adapters/Wi-Fi). This prevents further encryption and lateral movement.
    2. Identify and Terminate Processes: Use Task Manager (Windows) or process monitoring tools to identify and terminate the ransomware’s active processes.
    3. Boot into Safe Mode: For more thorough cleaning, boot the infected system into Safe Mode (with Networking, if necessary for updates/downloads) to prevent the ransomware from fully executing.
    4. Full System Scan: Perform a comprehensive scan using reputable antivirus/anti-malware software (ensure definitions are updated). This should detect and remove the ransomware executable and any associated files.
    5. Remove Persistence Mechanisms: Check common ransomware persistence locations, such as:
      • Registry Run keys (HKCU\Software\Microsoft\Windows\CurrentVersion\Run, HKLM\Software\Microsoft\Windows\CurrentVersion\Run)
      • Startup folders (shell:startup)
      • Scheduled Tasks (schtasks)
      • WMI (Windows Management Instrumentation) entries
    6. Review System Logs: Check event logs for unusual activity, failed logins, or suspicious process creations.

3. File Decryption & Recovery

  • Recovery Feasibility: As of current knowledge, there is no publicly available universal decryptor for Sage 2.0 Ransomware. The ransomware uses strong encryption algorithms (AES-256 for files, with the AES key encrypted by RSA-2048), making decryption without the attacker’s private key computationally infeasible.
  • Methods for Recovery:
    • Restore from Backups (Primary Method): This is the most reliable and recommended method. Restore encrypted files from clean, verified backups taken before the infection occurred.
    • Shadow Volume Copies: Sage 2.0 (like many ransomware strains) attempts to delete Shadow Volume Copies to prevent recovery. However, in some cases, if the ransomware failed to delete them, you might be able to recover previous versions of files using vssadmin commands or tools like ShadowExplorer. This method has a low success rate for this specific ransomware.
    • Data Recovery Services: In extreme cases, specialized data recovery firms might be able to help, but success rates for encrypted data are typically very low, and services are expensive.
  • Essential Tools/Patches:
    • Microsoft Security Updates: Ensure all Windows updates are applied, especially those related to system stability and security vulnerabilities.
    • Antivirus/Anti-malware Software: Keep your chosen security software (e.g., Windows Defender, Sophos, CrowdStrike, Carbon Black, etc.) fully updated.
    • Email Security Gateways: Tools like Proofpoint, Mimecast, or Microsoft Defender for Office 365.
    • Backup and Recovery Solutions: Reliable backup software (e.g., Veeam, Acronis, Rubrik, Cohesity) and cloud/offsite storage.

4. Other Critical Information

  • Additional Precautions:
    • Robust Encryption: Sage 2.0 stands out for its effective use of strong, dual-layer encryption (AES-256 and RSA-2048), which made direct decryption without the key practically impossible.
    • Ransom Note: Sage 2.0 typically leaves a ransom note named !_DECRYPT_INFO_!.txt in encrypted folders, providing instructions on how to pay the ransom (usually in Bitcoin) and contact the attackers.
    • Targeted Campaigns: While not as indiscriminate as WannaCry, Sage 2.0’s phishing campaigns were often sophisticated and could be highly effective in breaching organizations and individuals who were not prepared.
    • No Kill-Switch: Unlike WannaCry, Sage 2.0 did not have a known “kill-switch” domain that could halt its spread.
  • Broader Impact:
    • Sage 2.0 was part of the wave of highly impactful ransomware variants that emerged in 2017, collectively causing significant financial losses and operational disruptions globally.
    • It reinforced the persistent threat posed by phishing campaigns as a primary initial access vector, even as other ransomware families shifted to exploiting network vulnerabilities.
    • Its effectiveness underscored the critical importance of multi-layered security defenses, including technical controls, robust backup strategies, and comprehensive user training, to defend against evolving ransomware threats.