2k19

The ransomware variant identified by the file extension .2k19 represents a custom or less publicly documented strain, often associated with targeted attacks rather than widespread, wormable campaigns like WannaCry. While not as universally known as families like Ryuk or Conti, its impact on affected organizations can be severe. This detailed resource aims to provide technical insights and actionable recovery strategies.

---

Technical Breakdown:

1. File Extension & Renaming Patterns

• Confirmation of File Extension: The exact file extension used by this ransomware is .2k19.
• Renaming Convention: Upon successful encryption, the ransomware appends the .2k19 extension to the original filename. The typical renaming pattern follows this format:
  filename.original_extension.2k19
  For example:
  • document.docx would become document.docx.2k19
  • image.jpg would become image.jpg.2k19
  • archive.zip would become archive.zip.2k19
    Additionally, a ransom note is usually dropped in affected directories, often named README.txt, HOW_TO_DECRYPT.txt, or similar, containing instructions for payment and contact information.

2. Detection & Outbreak Timeline

• Approximate Start Date/Period: Variants using the .2k19 extension were primarily observed emerging and being active around late 2018 and throughout 2019. This period coincided with a surge in ransomware attacks leveraging common network vulnerabilities and insecure remote access methods. Its presence has been less prominent in subsequent years, though custom variants can always re-emerge.

3. Primary Attack Vectors

The 2k19 ransomware, like many targeted variants from that era, often relies on initial access facilitated by common weaknesses in network perimeter defenses.

• Remote Desktop Protocol (RDP) Exploits: This is a highly common initial access vector. Threat actors often
  • Brute-force attacks: Attempting to guess weak RDP credentials.
  • Exploiting exposed RDP services: Scanning for RDP ports open to the internet and then using compromised credentials (purchased from dark web markets) or brute-forcing them.
  • Vulnerability exploitation: While less common for direct RDP connection, unpatched vulnerabilities in Windows OS could allow privilege escalation post-RDP login.
• Phishing Campaigns:
  • Malicious Attachments: Emails containing seemingly legitimate documents (e.g., invoices, shipping notifications) with embedded malicious macros (VBA scripts) that, when enabled, download and execute the ransomware payload.
  • Malicious Links: Phishing emails leading to compromised websites or drive-by-download sites that deliver the ransomware.
• Software Vulnerabilities:
  • Unpatched Systems: Exploiting known vulnerabilities in operating systems (e.g., older SMBv1 vulnerabilities like EternalBlue, though less directly associated with .2k19 as a primary worming mechanism) or third-party software that allow for remote code execution or privilege escalation.
  • Exploitation Kits: Less commonly, exploit kits served via compromised websites could deliver the payload.
• Supply Chain Attacks: While less frequently confirmed for .2k19 specifically, the broader trend in 2019 included instances where malicious code was injected into legitimate software updates or widely used third-party components.
• Cracked Software/Loaders: Users downloading “cracked” versions of popular software or games from untrusted sources often inadvertently execute bundled malware, including ransomware.

---

Remediation & Recovery Strategies:

1. Prevention

Proactive measures are the most effective defense against .2k19 and similar ransomware.

• Robust Backup Strategy: Implement a “3-2-1” backup rule: at least three copies of your data, stored on two different media types, with one copy off-site or air-gapped/immutable. Regularly test recovery procedures.
• Patch Management: Keep all operating systems, applications, and firmware up to date with the latest security patches. Prioritize patches for known vulnerabilities, especially those related to RDP, SMB, and common applications.
• Strong RDP Security:
  • Disable RDP if not needed.
  • Use strong, unique passwords and Multi-Factor Authentication (MFA) for all RDP accounts.
  • Limit RDP access: Restrict RDP access to specific IP addresses or VPNs. Never expose RDP directly to the internet.
  • Network Level Authentication (NLA): Enable NLA for RDP connections.
• Endpoint Security: Deploy and maintain up-to-date antivirus/anti-malware solutions with EDR (Endpoint Detection and Response) capabilities on all endpoints and servers.
• Network Segmentation: Divide your network into isolated segments to limit the lateral movement of ransomware in case of a breach.
• User Awareness Training: Educate employees about phishing, suspicious emails, and safe browsing habits. Conduct regular simulated phishing exercises.
• Principle of Least Privilege: Grant users and applications only the necessary permissions to perform their tasks.
• Application Whitelisting: Implement application whitelisting to prevent unauthorized executables from running.

2. Removal

If an infection is detected, immediate and methodical steps are crucial.

• Isolate Infected Systems: Disconnect the infected machine(s) from the network immediately (unplug Ethernet cables, disable Wi-Fi). This prevents further encryption or spread.
• Identify the Infection Point: Determine how the ransomware gained access. This is critical for preventing re-infection. Check RDP logs, firewall logs, email server logs, and user activity.
• Scan and Clean:
  • Boot the infected system into Safe Mode or use a bootable anti-malware rescue disk (e.g., from Emsisoft, Kaspersky, Bitdefender).
  • Perform a full system scan with reputable anti-malware software to detect and remove the ransomware executable and any associated malicious files or persistence mechanisms (e.g., registry entries, scheduled tasks).
• Check for Persistence: Manually inspect common persistence locations (e.g., HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run, HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run, %APPDATA%\Microsoft\Windows\Start Menu\Programs\Startup, Task Scheduler).
• Change All Passwords: Especially for any accounts that might have been compromised (e.g., RDP credentials, domain admin accounts).

3. File Decryption & Recovery

• Recovery Feasibility:
  • Direct Decryption: As of the latest information, there is no publicly available universal decryptor for files encrypted by the .2k19 ransomware. This variant likely uses strong, modern encryption algorithms (e.g., AES-256 for file encryption, RSA for key exchange) and does not have known cryptographic weaknesses that allow for free decryption. Therefore, direct decryption without the attacker’s private key is generally not possible.
  • Recovery from Backups: The most reliable and recommended method for file recovery is to restore from clean, uninfected backups. Ensure that the backups themselves are not compromised before initiating restoration.
  • Shadow Copies: While some ransomware variants attempt to delete Volume Shadow Copies (vssadmin delete shadows /all /quiet), it’s always worth checking if they exist. Use tools like ShadowExplorer to see if previous versions of files are available. If VSS copies were enabled and not deleted, you might be able to recover some older versions of files.
• Essential Tools/Patches:
  • Up-to-date Anti-malware Software: Emsisoft, Malwarebytes, Kaspersky, Bitdefender, Microsoft Defender ATP.
  • Windows Updates: Ensure the operating system is fully patched.
  • Backup Solutions: Reliable software/hardware for creating and managing backups (e.g., Veeam, Acronis, cloud backup services).
  • Forensic Tools: For incident response and identifying the root cause (e.g., Sysinternals Suite, Wireshark).

4. Other Critical Information

• Additional Precautions:
  • No Ransom Payment: Cybersecurity experts and law enforcement generally advise against paying the ransom. There is no guarantee that paying will result in decryption, and it can further fund criminal activities, encouraging more attacks.
  • Evidence Collection: Before wiping or reinstalling, if possible, collect forensic evidence (logs, memory dumps, disk images) to aid in understanding the attack and potentially identifying the actors. This is especially important for organizations.
  • Monitor Network Traffic: After initial cleanup, continuously monitor network traffic for any anomalous activity that might indicate lingering presence or attempted re-infection.
• Broader Impact:
  • Data Loss: The primary and most devastating impact is the permanent loss of encrypted data if no viable backups or decryption keys are available.
  • Operational Disruption: Ransomware attacks significantly disrupt business operations, leading to downtime, lost productivity, and potential financial losses.
  • Reputational Damage: For organizations, an attack can severely damage public trust and reputation.
  • Financial Costs: Beyond the potential ransom, costs include incident response, forensic investigation, system rebuilding, legal fees, and potential regulatory fines (e.g., GDPR, HIPAA) if data exfiltration occurred.
  • Data Exfiltration Risk: While 2k19 itself is an encryptor, many threat actors now combine encryption with data exfiltration (double extortion). Always assume sensitive data might have been stolen, and initiate data breach notification procedures if applicable.

By adhering to these prevention, removal, and recovery strategies, individuals and organizations can significantly reduce their risk and mitigate the devastating effects of the .2k19 ransomware and similar threats.