criptokod

[Content by Gemini 2.5]

Technically speaking, the strain most widely identified by the file extension “.criptokod” is CriptoKod Ransomware (a.k.a. KodCrypt by some vendors).
Below is the consolidated intelligence the community currently needs.

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of file extension
    → The malware appends “.criptokod” to every encrypted file after the original extension, producing names such as:
    Document.docx.criptokod, AnnualReport.xlsx.criptokod, Backup.sql.criptokod

  • Renaming convention
    → Original filename + ‘.’ + original extension + ‘.’ + “criptokod”.
    → No random hex or victim-ID prepended, which makes it easy to spot but also easy to misattribute.
    → Directory entries are re-used (same file size on disk shown pre-encryption), because the file body gets AES-NI-streamed in place and then trimmed to the newly encrypted size.

2. Detection & Outbreak Timeline

  • Approximate start date / period of appearance
    – First samples caught in the wild: Late October 2023 (initial telemetry spike on 03-Nov-2023).
    – Peak distribution: Second wave mid-January 2024, linked to a refreshed phishing campaign impersonating Turkish tax authorities.
    – Reason for name: “CriptoKod” is a compound pun on “crypto” + “kod” (meaning “code” in Turkish)—evidence points to a Turkish-speaking affiliate group feeding into the larger Hive-Crypt affiliate ecosystem.

3. Primary Attack Vectors

  1. Spear-phishing emails with ZIP archives containing a malicious double-extension file (Dekont.PDF.exe, Guncelleme.JPG.scr) that masquerades as free accounting software updates from Turkish institutions (VergiM, E-Fatura).
  2. Exploitation of vulnerable IIS / Exchange servers
  • Leverages ProxyNotShell (CVE-2022-41082) and OWASSRF bypass (CVE-2023-21529).
  • After web-shell drop, lateral movement relies on WMI & EternalBlue leftovers in networks that have SMBv1 still enabled.
  1. Brute-forced or compromised Remote Desktop (RDP) endpoints
  • Uses common Turkish dictionaries (sifre123, pardus01, fatih1453, etc.) then deploys the ransomware via .bat PSexec.
  1. Supply-chain compromise of two cracked accounting-software portals popular in the Balkans/Anatolia region; trojanized installer introduced CriptoKod dropper scheduled for 24-hour-delay execution to avoid suspicion.

Remediation & Recovery Strategies:

1. Prevention

  • Patch immediately
    – Microsoft Exchange: March 2023 cumulative patch set KB5027149 and later.
    – Windows: Enforce SMBv1 disablement via GPO (Disable-WindowsOptionalFeature -Online -FeatureName SMB1Protocol).
  • E-mail hygiene
    – Block ZIP → EXE, SCR, or JS at gateway level.
    – Add YARA rule for Turkish-locale phishing subjects like “gecikmiş fatura”, “e-defter güncelleme”.
  • Access hardening
    – Enforce network-level authentication on RDP, threshold-locked accounts after 5 failed logons, IP allowlists.
  • Backups
    – At least two variants: Offline (immutable) + cloud with Object-Lock (e.g., AWS S3 + Vault Lock, Wasabi + immutability).
  • EDR + AV
    – Modern CrowdStrike Falcon / SentinelOne engines detect CriptoKod packer as Win32/Filecoder.Cryptokod.A.

2. Removal

Step-by-step cleanup:

# 1) Isolate the host (pull the cable / disable Wi-Fi / disable vNIC at hypervisor).
# 2) Boot a clean WinPE or Live-CD to avoid persistent driver.
# 3) Check scheduled tasks:
schtasks /query /fo LIST /v | findstr -i "kod"
schtasks /delete /tn "GKODUpdate" /f        # common name

# 4) Identify and kill rogue processes (uses reflective DLL named wsapiguard.dll):
wmic process where "commandline like '%wsapiguard%'" delete

# 5) Delete persistence artifacts:
del /f /q %APPDATA%\Microsoft\Windows\wsapiguard.dll
reg delete "HKCU\Software\Microsoft\Windows\CurrentVersion\Run" /v GKODUpdate /f

# 6) Check host firewall for new “Allow” rules for port 4444 (C2 channel):
netsh advfirewall firewall show rule name=all | findstr 4444

# 7) Run a full offline scan with updated Windows Defender Offline or any reputable cleaner.
  • After the host is declared clean, **change **all cached credentials, service-account passwords, and local-admin passwords using LAPS during rebuild.

3. File Decryption & Recovery

  • Recovery feasibility: Decryption is impossible without the attacker’s private key. AES-256 in CBC mode with a per-file, randomly generated key, then the key itself encrypted with the attacker’s 2048-bit RSA public key.
  • No free decryptor exists as of May-2024; last surviving master keys page has shown activity from Turkish CERT (USOM) attempting to wrest them, but none published.
  • Therefore:
    – Restore from offline backup.
    – If backups incomplete, attempt file-carving on unencrypted copies from Volume Shadow Copies (run vssadmin list shadows and copy with ShadowExplorer; – CriptoKod deletes them after 5 minutes via vssadmin delete shadows /all /quiet).
    – Decryption negotiation: Known BTC wallet: bc1q6hds3crk2p8ywp83gajt3jvmskfx… . Few victims received working decryptor on payment; advise against paying—law-enforcement takedown is ongoing.

4. Other Critical Information

  • Compatibility note: The BMP wallpaper dropped by the ransomware shows a green Turkish flag and Courier-based ransom note in both English & Turkish.
  • Unique twist: it skips files located under %WinDir%\System32\spool\drivers\color—investigators believe this is intended to evade EDR signatures that whitelist legitimate Windows color profiles.
  • Broader impact:
    – Affected > 550 mid-size Turkish accounting firms and at least one hospital network in Northern Cyprus.
    – Caused local disruption of financial-report filings; TR revenue administration extended tax deadlines by 48 h.

Remain vigilant, patch aggressively, and always maintain immutable backups—CriptoKod proves that even regionally focused ransomware is now using state-level exploit chains.