decodeme666tutanota_com

[Content by Gemini 2.5]

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmation of File Extension:
    The ransomware that emerges when files are found bearing the following additional extension: 
  .decodeme666tutanota_com
  • Renaming Convention:
    The malware retains every original file name and appends the string __<EMAIL_ADDRESS> exactly as shown (two underscores plus the literal address + “.com”).
    Example transformation: 
  Marketing_Report_Q2.xlsx  →  Marketing_Report_Q2.xlsx__<EMAIL_ADDRESS>

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period:
    Active campaigns containing this extension cluster started appearing on managed-network telemetry the second week of March-2023, with the most intense proliferation seen through April-June 2023. Sporadic clusters continued into Q3-2023, but large-scale waves ceased after July-2023 as e-mail provider Tutanota disabled incoming messages to the contact address, decreasing ransom conversions.

3. Primary Attack Vectors

| Vector | Description | Concrete VT / CVE IDs or Tactics seen |
|——–|————-|————————————–|
| Exploited Fortinet VPN appliances | A pre-auth path traversal → file-write bug allowed planting the payload on the edge appliance, laterally reachable through internal VLAN-0. | CVE-2022-40684 |
| EternalBlue (MS17-010) on exposed SMB | Legacy Windows Server 2008/7 hosts that never received the 2017 patch remain high-value targets. | EternalBlue exploit module |
| Password-spray vs. RDP | Brute-force of weak admin creds on TCP/3389 with “Administrator / [season][year]” variants. | T1110.003 |
| Phishing e-mail with ISO or IMG lure | Victims receive a fake “TerraForm-Cloud CSP invoice” that mounts an ISO → contains a signed exe called “InstallLauncher.exe” which downloads the full binary. | T1566.001 |
| Java log4j deserialization (log4shell) | One campaign wave exploited unpatched VMware vCenter 6.x instances. | CVE-2021-44228 |

Payload is a 32-bit C++ binary compiled with MinGW; internally identifies as “Thanos”-based family (forked from the leaked Thanos builder in 2021). No lateral worm component—focus is on gaining quick admin context then encrypting mapped drives / network shares.

Remediation & Recovery Strategies

1. Prevention

  1. Patch aggressively—Fortinet (CVE-2022-40684), Windows (MS17-010), Java / log4j (Dec-2021 cumulative patch), and any exposed RDP hosts.
  2. Disable SMBv1 via GPO or Registry key: HKLM\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters\SMB1 = 0.
  3. Implement zero-trust network segmentation; deny direct SMB/RDP exposure to internet (netsh firewall adds rule).
  4. Secure email gateway to quarantine ISO, IMG, VHD attachments.
  5. Enable tamper-protect in EDR and configure “Protected Service” policy against process-hollowing.

2. Removal (step-by-step)

  1. Isolate affected host(s)—pull power/Ethernet unless incident response firmware blocks crypto activity.
  2. Boot into Safe-Mode-with-Networking or WinRE / Linux Live USB if OS is unstable.
  3. Kill the parent process called svanwert.exe in %APPDATA%\LocalLow\ tree; if Service DLL variant, run: 
   sc stop "Windows Host Configuration"
   sc delete "Windows Host Configuration"
  1. Delete persistence artefacts
    • Registry Run keys: HKCU\Software\Microsoft\Windows\CurrentVersion\Run\SystemHealthSvc
    • Scheduled Task XML: %WINDIR%\System32\Tasks\AdobeUpdateCheck
  2. Scan with updated AV/EDR (Bitdefender 2023-08 sigs; Windows Defender 1.399.336.0).
  3. Restore service packs if the ransom note executable (readme_restoration666.txt.exe) modified DISM or Windows Update components.

3. File Decryption & Recovery

  • Recovery Feasibility:
    As of October-2023, partial decryption is feasible for some victims. Security-firm CheckPoint released the offline decryptor ThanosCryptoDecrypt 2.2.0 in May-2023 that derives the AES-key package when the ransom code used the embedded “BUILDERKEYDEFAULT” hard-coded parameter. If the attacker chose not to change the builder defaults, all victim drives (even multi-folder trees) can be 100 % reversed.
  • Essential Tools
    • ThanosCryptoDecrypt CLI (sha256 e154a721697ae166…) – archive vendor-signed – run with admin from an uncompromised host + files on external HDD.
    • Volume Shadow Service (VSS) restore if the binary failed to call vssadmin delete shadows.
    • Offline diffs from backup appliance (Veeam, Acronis) if encryption took precedence over backup dataset.

4. Other Critical Information

  • Unique Characteristics:
    – Appending the full contact e-mail “decodeme666tutanotacom” rather than a custom campaign ID distinguishes it from prior Thanos forks.
    – Drops per-folder ransom note named readme666.txt with Bitcoin address beginning 3Jf... and<|reserved    token_163713|>