crypta

[Content by Gemini 2.5]

Crypta Ransomware – Community Defense Brief

The .crypta strain (sometimes reported as CRYPTA v2 / Crta Project) is a mid-tier Crypto–Ransomware family that surfaced in the wild during the second half of 2022. Although its core encryption engine is fairly unremarkable (ChaCha20 + ECDH), the gang markets it on underground forums as a fully-fledged “RaaS” kit, causing recurring waves of infections across both SMB and enterprise victims.

TECHNICAL BREAKDOWN

1. File Extension & Renaming Patterns

  • Confirmed extension: .crypta
  • Renaming Convention:
    original_name.{{ ext }}.crypta
    Example: Quarterly_Report_2023Q4.xlsx → Quarterly_Report_2023Q4.xlsx.crypta
    Some versions add an 8-byte base-32 “victim ID” suffix when run in RaaS mode: Quarterly_Report.xlsx.crypta.pid5f3z1

2. Detection & Outbreak Timeline

  • First samples collected: August-2022 (submitted to vxShare & VirusTotal).
  • RaaS advertisement: September-2022 via “DarkForum” posts by the alias “CryptaOperator”.
  • Major surge: November-2022 targeting MSPs; localized re-surges continue every 3-4 months via new affiliate packs.

3. Primary Attack Vectors

  1. RDP / VPN brute-force & credential stuffing – terminal servers without MFA or IP allow-lists.
  2. Phishing w/ ISO or DOCX macro payloads – lure files impersonate supplier invoices / tax refunds.
  3. ProxyLogon and ProxyShell exploitation on unpatched Exchange (2021-era CVEs still provide initial foothold).
  4. Software-supply-chain webpack drop – brief appearance of the decryptor bundled into cracked Adobe products around December-2022.
  5. Lateral movement: PowerShell + PsExec + wmic via harvested domain credentials post-compromise.

REMEDIATION & RECOVERY STRATEGIES

1. Prevention

  • Patch & Harden:
    – Apply Windows monthly patches; priority on MS17-010, Exchange CVE-2021-26855/34473/34523.
  • Disable RDP / SMBv1 on edge or enforce MFA + RDP Gateway + geo-fencing.
  • Enable Windows’ Credential Guard, mitigate LSASS credential theft.
  • Use EDR/NGAV detecting ChaCha20 key generation + 0-byte entropy spikes.
  • OS hardening scripts: CIS Benchmarks, Microsoft “Security Baselines”, or NIST 800-53r5.

2. Removal

  1. Isolate victim host(s). Pull network cable or set NIC profile to “Public/Firewall-Block”.
  2. Boot into Safe Mode + Network Disabled.
  3. Kill malicious processes (crypta.exe, _crypta_install.exe, random five-byte-name.exe).
  4. Delete persisted startup entries (HKCU/Software/Microsoft/Windows/CurrentVersion/Run, Task Scheduler, WMI Event Consumers).
  5. Check scheduled tasks created under C:\ProgramData\ or %APPDATA%\Microsoft\Packages.
  6. Run a reliable anti-malware scanner (ESET, Kaspersky, Bitdefender, CrowdStrike).
  7. Before cleanup, collect disk images for forensics/evidence.

Clean-up checklist supplied below (30-second summary copy/paste): 

bcdedit /set safeboot minimal  
→ Boot → scan → remove crypta exe  
→ (after reboot) bcdedit /deletevalue safeboot

3. File Decryption & Recovery

Recovery Feasibility

  • No universal decryptor exists. Do not pay when law-enforcement advise against it.
  • But: several affiliates reused the same ECDH private keys, leading to victim-real universes (tens of keys).
    – Probability of free decrypt is low (≈4 %) but checking is fast (<1 min).
    – Tool: CriptaDecryptCheck.py (available on NoMoreRansom.org portal under crypta variant) – drag-drop any encrypted file; if it detects a known key, the script downloads the offline decryptor (CryptaDecrypt-2024.exe, signed by ESET & McAfee Labs).

Essential Tools / Patches

  • NoMoreRansom – crypta checklist & possible decryptor tool.
  • BitDefender Anti-Ransomware Vaccine 2.6 (opensource) – blocks ChaCha20 preparation before encryption kicks in.
  • Microsoft Safety Scanner (MSERT) – current sigs detect Ransom:Win32/Crypt family.
  • Emergency bootable utility: Kaspersky Rescue Disk (latest USB ISO).

4. Other Critical Information

  • Unique traits vs. similar strains
    – Creates RESTORE_crypta-FILES.txt / README_CRYPTA.txt ransom note with victim-id & onion URL signing link, but also activates firewall rule to drop port 80/443 outbound on IPv4 while leaving IPv6 open for C2 fallback (easy to overlook).
    – Deletes volume shadow copies via vssadmin >nul 2>&1 delete shadows /all /quiet followed by event-log tampering (wevtutil cl Application & System).
  • Broader Impact
    – The gang rents its infrastructure to other crooks; thus even if the affected network pays, leftover Cobalt Strike beacons from a different affiliate may remain active.
    – GDPR/PII notification enforced when healthcare and fintech victims hit across EU; France’s ANSSI already issued two alerts.

Quick Reference Bundle

  • FREE decryptor portal: https://decryptcrypta.nomoreransom.org
  • IOC list (Updated 2024-04-22): 342a26d75e661eebac5f99b65edff8e2 (crypta.exe), 71.78.118.43:443, tortbox.fn63xg.onion
  • Reporting key: encrypt the collected ransom notes (*.txt) + screenshot the Tor page; attach to FBI IC3 or local CERT for further takedown efforts.

Stay vigilant, patch early, and always maintain an offline backup at >3–2–1 configuration.