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:
- Files remain in their original folder/drive structure.
- Enumeration happens from the local drives → mapped shares → removable devices in that order.
- After encryption each file becomes:
<original_name.ext>.coinvault
. - 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
-
Patch Strictly:
• Flash, Java (v6–v8 < u40), Silverlight, Internet Explorer, Windows KB updates through June 2015. -
Harden RDP:
• Restrict to VPN, Network Level Authentication ON, account-lockout policy. -
Network Segmentation:
• Isolate file servers from end-user VLAN; block lateral SMB port 445 between segments. -
Email Hygiene:
• Sanitize ZIP archives with password protection. -
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)
-
Isolate & Identify:
a. Disconnect ethernet/Wi-Fi.
b. Runnetstat -aob
orGet-NetTCPConnection
to look forcoinvault.exe
,serv.exe
or random-name process in%AppData%\Roaming\
. - Create Forensic Image before modification in case decryption fails.
-
Kill Malicious Processes:
• Via Safe-Mode-with-Networking ‑> taskkill /PID<id>
/F -
Delete Persistence Items:
• Registry:HKCU\Software\Microsoft\Windows\CurrentVersion\Run
key namedCoinVault
→ value path to%AppData%\Roaming\coinvault.exe
.
• Scheduled Tasks:schtasks /delete /TN "CoinVault Update" /f
. -
Remove Leftovers:
• Delete%AppData%\Roaming\coinvault.exe
&coinvault_filemap.wvd
in every affected volume root. -
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:
-
Kaspersky RakhniDecryptor 3.11.0+ supports all known CoinVault keys.
• Obtain tool & keys from: https://noransom.kaspersky.com -
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. - 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.