coinvault

[Content by Gemini 2.5]


Technical Breakdown – “CoinVault” ransomware

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: All encrypted files are given the literal suffix
    “.coinvault” (e.g., Report_Q4.xlsx.coinvault) – this string is appended; the original extension is preserved in front of it.
  • Renaming Convention:
  1. Files remain in their original folder/drive structure.
  2. Enumeration happens from the local drives → mapped shares → removable devices in that order.
  3. After encryption each file becomes: <original_name.ext>.coinvault.
  4. An accompanying coinvault_filemap.wvd (Windows Vista+/7 “Restore Point” format) is dropped in each directory to track encryption metadata.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period:
    • First sample uploaded to a public malware repository: 29 November 2014.
    • Rapid distribution spike seen in late-December 2014 followed by a second wave in Q2-2015.
    • Dutch law-enforcement announced two arrests of CoinVault authors on 14 September 2015 – incident counts fell sharply afterward.

3. Primary Attack Vectors

| Vector | How CoinVault uses it | Example | Mitigation note |
|—|—|—|—|
| Exploitation kits | Angler EK on compromised ad networks delivered the CoinVault dropper. | Drive-by downloads from exploit page via Flash CVE-2014-0515. | Disable or fully patch Flash. |
| Vulnerable RDP | Port 3389 brute-forced, then the ransomware binary setup.exe copied into Startup. | IP ranges scanned on TCP/3389 from 109.XX.XX.XX subnets. | Use VPN + 2FA, change 3389 → non-default, disable NLA fallback. |
| Malicious e-mail | ZIP with SCR prefix (double-file-extension trick). | Invoice2015.zip → Invoice2015.pdf.scr. | Block .scr/.hta/.js at the mail gateway. |
| SMBv1 (Minor) | Early versions attempted to propagate across shares internally – not worm-like like WannaCry but enough to crawl through flat networks. | Exploits CVE-2008-4250 patterns when shares allowed write-execute. | Disable SMBv1 across estate. |


Remediation & Recovery Strategies

1. Prevention

  1. Patch Strictly:
    • Flash, Java (v6–v8 < u40), Silverlight, Internet Explorer, Windows KB updates through June 2015.
  2. Harden RDP:
    • Restrict to VPN, Network Level Authentication ON, account-lockout policy.
  3. Network Segmentation:
    • Isolate file servers from end-user VLAN; block lateral SMB port 445 between segments.
  4. Email Hygiene:
    • Sanitize ZIP archives with password protection.
  5. Backups:
    • 3-2-1 rule with offline/offsite copy; turn on Windows Volume Shadow Copy (VSS) because CoinVault does attempt—and often fails—to delete VSS.

2. Removal (step-by-step)

  1. Isolate & Identify:
    a. Disconnect ethernet/Wi-Fi.
    b. Run netstat -aob or Get-NetTCPConnection to look for coinvault.exe, serv.exe or random-name process in %AppData%\Roaming\.
  2. Create Forensic Image before modification in case decryption fails.
  3. Kill Malicious Processes:
    • Via Safe-Mode-with-Networking ‑> taskkill /PID <id> /F
  4. Delete Persistence Items:
    • Registry: HKCU\Software\Microsoft\Windows\CurrentVersion\Run key named CoinVault → value path to %AppData%\Roaming\coinvault.exe.
    • Scheduled Tasks: schtasks /delete /TN "CoinVault Update" /f.
  5. Remove Leftovers:
    • Delete %AppData%\Roaming\coinvault.exe & coinvault_filemap.wvd in every affected volume root.
  6. Update AV Signatures: Current detections – Ransom:Win32/Coinvault.* (Microsoft), Trojan-Ransom.Win32.Coins (Kaspersky). Scan entire system.

3. File Decryption & Recovery

  • Recovery Feasibility: YES – DECRYPTOR EXISTS.
    Belgian Federal Police + Kaspersky Lab leveraged seized author servers to generate 4 000+ private keys.
  • Tools & Methods:
  1. Kaspersky RakhniDecryptor 3.11.0+ supports all known CoinVault keys.
    • Obtain tool & keys from: https://noransom.kaspersky.com
  2. Manual Key Pair: If you have a ransom note (HOW_TO_DECRYPT_FILES.txt) containing “IV” and “Key ID”, submit via the above URL; you may receive a custom extractor.
  3. Silent VSS Restore: Many enterprises recovered 90 %+ of files via right-click → “Previous Versions” (shadow copies) before decryption attempt.

4. Other Critical Information

  • Unique Feature:
    • CoinVault implemented the Dutch-language ransom UI (rare at the time) and displayed a timer-countdown GIF; the amount reduced by 1 BTC/day within 72 h, a psychological trick meant to hurry payment.
  • Law-Enforcement Aspect:
    • Arrest in the Netherlands led to the seizure of decryption keys – a landmark case where paying the ransom became unnecessary.
  • Wider Impact:
    • Although smaller in reach than CryptoLocker or TorrentLocker, CoinVault catalysed EU-wide ransomware task-force co-operation (Europol’s “No More Ransom” initiative, launched April 2016).

Bottom line: If you are facing .coinvault files today, do not pay. Use the free Kaspersky decryptor, triple-check backups/Shadow Copies, and implement hardened RDP controls and spam-filtering to ensure it does not return.