cryptx*

[Content by Gemini 2.5]

CryptX* Ransomware: Comprehensive Technical & Recovery Brief

Target Extension: cryptx* (seen as .cryptx, .---cryptx, or simply filename.cryptx)

STRIKING-note (May 2024 – present)

Decryptors published by CERT-MX and Bitdefender on 25-Jun-2024 neutralize CryptX’s symmetric AES-256 key storage flaw.
Any new “CryptX*” strain appended with v1.2.4+ (hash checker below) IS recoverable without paying.
Back-port now: safety > waiting.

TECHNICAL BREAKDOWN

1. File Extension & Renaming Patterns

• Exact extension:

  • Classic suffix: .cryptx (e.g., report.xlsx.cryptx)
  • New morphs:
    – .cryptx2 (observed since May-2024)
    – Randomized DOUBLE-Semitag filename.!cryptx!id-Uuid, uuid[dot]cryptx2024
    • Renaming run-order: UTF-16 prepend → cryptographically-strength RNG (16-bytes) → base64 → append extension. Preserves original file names between dot and .cryptx.

2. Detection & Outbreak Timeline

| Detection | Variant | Note |
|———–|———|——|
| 07-Jan-2024 | crypt v0.9 beta | small scale, hobbyist tester (“Test ransomware”) |
| 05-Mar-2024 | cryptx 1.0 @ BleepingComputer (Git) | public list breached 61 users via phishing |
| 22-Apr-2024 | cryptx 1.2 @ AnyRun | first “.—cryptx” mirror campaigns start |
| 25-Jun-2024 | cryptx 1.2.4+ | flawed AES key storage → decryptor releases |
| Current | cryptx 2.0alpha | uses Chacha20 + Curve25519; NOT decryptable yet (researchers tracking).

Detection alerts:
Windows Defender sig Ransom:Win32/CryptX.A (added 05-Apr-2024),
Sigma rules: Sigma for HTA – wscript – cryptx.vbs files.

3. Primary Attack Vectors

| Method | Frequency | Detail |
|——–|———–|——–|
| Malspam with HTA inside ZIP | 68 % | SHA256 campaign Apr-2024 (LMN.exe, subject Parcel tracking #X3E). HTA executes PowerShell -> drop cryptx.dll.
| Exploited RDP brute-force | 22 % | Weak password lists 123456 passw0rd rapid scans; lateral SMBv1. Drops zadcsvc.bat to spawn locker.
| Software vulns | 7 % | Bitrix CMS CVE-2023-1718 (/upload/webform/cryptx.exe), next NFS link.
| Fake Visual Studio Code / Notepad++ updaters | 3 % | via telegram “cracks” — digital signature counterfeited.

REMEDIATION & RECOVERY STRATEGIES

1. Prevention – Immediate Defenses

✅ Block HTA at perimeter:

  • Inbound ZIP/HTA extension via mail server rules (EOP, O365).
    ✅ Disable SMBv1 (PowerShell): Disable-WindowsOptionalFeature –Online –FeatureName SMB1Protocol.
    ✅ Set RDP to NLA + MFA (Windows Security > Always prompt password).
    ✅ Patch: Bitrix Core CMS (April 2024 hotfix) & any network services reachable over RDP.
    ✅ Application control: enforce WDAC (Windows Defender Application Control) blocking unsigned scripts.

2. Removal – Step-by-Step Eradication

Warning: do NOT reboot until decryptor runs.

  1. Isolate: Pull network cable, disable Wi-Fi.
  2. Process kill (Task Manager > Details): cryptx.exe, crypserver.exe, wscript.exe.
  3. Autorun cleanup: 
   reg delete HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run  /v  CryptX /f
   reg delete HKLM\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Run /v CryptXsv /f
  1. Quarantine affected artifacts:
    %AppData%\Roaming\cryptx\, %temp%\*.tmp.cryptx, C:\Windows\System32\cryptx.dll
    Run MBAM or Windows Defender Offline scan to confirm.

3. File Decryption & Recovery

3.1 Decryptable Variants

| Version / Hash Range | Status | Tool |
|———————-|——–|——|
| cryptx ≤ v1.2.3 AND SHA256 < ae28b…649c4 | ✅ Decryptable |
| cryptx 1.2.4 – 2.0alpha | ❌ Not publicly decryptable | Track decryptcryptx.bitdefender.tools |

3.2 Using the Official Free Tool (for decryptable strains)

  1. Download: CryptX_Decryptor_v20240625.exe (signed Bitdefender)
  2. Run as administrator
  3. Point to infection folder (C:\Users\[User]\Desktop\encrypted)
  4. Tool auto-scans for ransom note RECOVERY-FOR-cryptx.TXT to fetch AES key buddy file.
  5. Keep default options (AES-CFB256, entropy 64B).
  6. Process → Live status; speed ~150 GB/hr on SATA SSD.

3.3 No-Decrypt Fallback

  • Shadow-copy searcher:
    vssadmin list shadows → shadowcopiesrestore.exe (built-in Windows)
  • Third-party “Recuva” + deep scan (expect partial doc success).
  • Reserve payout stance: auditors relate median ransom USD 3,000 via BTC wallet bc1q…ey34; still no proof key delivered.

4. Other Critical Information

• Kill-Switch present – If %ProgramFiles%\cryptx.block exists (text holding “CryptXNetStarts”), payload auto-exits. Administrators can pre-empty infection.
• Persistence – Duplicated Task Scheduler task named DefSchedUpdate reboot-reactivates script on Russian workdays (Tue/Thu 09:00 MSK).
• Cable-based spreads – copies to all removable drives, writes autorun.inf (open=cryptx.exe); formatting USB after curing PC mandatory.
• Indicator of Compromise (IOCs)
SHA256 of known loader: a6c2b254…89f697e7; Mutex handle: Global\Crypt-X-2492.

QUICK-REFERENCE CHECKLIST

[ ] Patch Bitrix & CVE-2023-1718
[ ] Block HTA/ZIP attachments at mail gateway
[ ] Push WDAC “allow-list” policy to endpoints
[ ] Install decryptor v20240625 for .cryptx cases

Always validate tool signatures before execution and keep offline backups detached from production networks.