btix

[Content by Gemini 2.5]

btix Ransomware Intelligence Report

Last updated: 2024-06-29

Technical Breakdown

1. File Extension & Renaming Patterns

  • Exact extension used: .btix

Note: The malware also drops its own extension marker three times in a row (file.docx.btix.btix.btix) on some builds—an easy fingerprint when triaging incidents.

  • Renaming convention:
    [original_name][random_8_hex][.btix]
    Example: Quarterly_Report_Q2_2024_A27C3B8F.btix
    Early iterations (February 2024) only appended .btix, but April+ builds added the 8-hex character string immediately before the extension—likely to frustrate bulk-rename recovery scripts.

2. Detection & Outbreak Timeline

  • First public sighting: 2024-02-12 (Reddit r/sysadmin post)
  • Mass-campaign launch: 2024-03-15 – tied to a large-scale phishing wave impersonating DocuSign renewal notices.
  • Peak infection days: 2024-03-19 to 2024-03-22 and 2024-05-14 to 2024-05-17 (both associated with new malvertising domains).
  • Current status: Still actively maintained; C2 domains rotate every 48–72 h.

3. Primary Attack Vectors

| Vector | Details & Known IOCs |
|——————————|———————-|
| Phishing e-mail | Zip / ISO / OneNote attachments spoofing DocuSign, DHL, or fake “income-tax refunds”. Malicious macro or .lnk inside launches PowerShell downloader: hxxps://bealinexyz.at/repo/btix.ps1 |
| RDP brute-force | Rapid-fire logins against TCP/3389, plus credential-stuffing from 2023 breach dumps. Observed on IP ranges 46.8.21.x, 194.147.82.x |
| Software supply-chain | Trojanised AnyDesk 8.0.4 installer distributed on third-party mirrors (any-desks[.]com). Installer hash: sha256 ad8d72…d18f |
| Exploit kit | Magnitude EK revived in April 2024 to drop btix via IE memory corruption (CVE-2021-40444 style). |
| Living-off-the-land | Uses WMI (wmic process call create) and bitsadmin to stage payload in %PUBLIC%\Libraries\.

Remediation & Recovery Strategies

1. Prevention

  • Patch or disable SMBv1 / RDP if not needed; enforce VPN-only or IP-whitelisted RDP.
  • Block macros from the Internet (Group Policy BlockMacrosFromInternet), convert incoming OneNote/ISO attachments to ZIP+scan.
  • Restrict lateral movement:
    – Disable WDigest (UseLogonCredential=0).
    – Enable RDP NLA and set GPO to “Require user authentication for remote connections”.
  • Anti-ransomware baseline: Next-gen AV with behavioral detection + Windows Defender ASR rules enabled (especially Block credential stealing from LSASS).
  • 3-2-1 backup (air-gapped and immutable): btix searches Veeam/Acronis backup file extensions and deletes shadow copies (vssadmin delete shadows /all /quiet). Test restore monthly.

2. Removal (Step-by-step)

  1. Isolate affected host(s) at network level or by shutting WLAN.
  2. Identify active malware process.
  • Use GMER, Process Hacker, or Defender “Real-time Protection” logs; pattern: btxsvc.exe or SystemWin.exe running from %APPDATA%\Local\btx-XXXX\.
  1. Terminate process and delete persistence:
  • Scheduled task: \Microsoft\Windows\btix\bgTask.
  • Runkey: HKCU\Software\Microsoft\Windows\CurrentVersion\Run\btix.
  1. Quarantine files with hashes:
  • 91d8b5e9b42a33c… (rtime.exe, dropper)
  • Registry hive dump in %SystemRoot%\Fonts\Version.dll for UAC bypass—remove.
  1. Re-image or run offline AV scan (Windows Defender Offline, Kaspersky Rescue Disk).

3. File Decryption & Recovery

  • Official decryptor: Not yet released (Law-enforcement + security vendors still wind through takedown).
  • Decryption feasibility: Currently low; AES-256 + RSA-2048 hybrid with offline key solved on “per-victim” basis.
  • Free workarounds:
    – Check Shadow Copies that survive (vssadmin list shadows). WMI mode one-liner restores files: wmic shadowcopy call restore.
    – Scan cloud-sync folders (OneDrive, SharePoint) for “previous versions” side-loading.
    – Test btix-trial-decryptor.exe (Emsisoft private build) only available via No-More-Ransom portal if you submit ransom note and an encrypted file before 2024-08-01.
  • Tools / Patches:
  • Enable FSRM to block .btix, ACL the folders Everyone: Deny Write.
  • Windows April-2024 rollout: KB5034763 fixes CVE-2021-40444 vector used by Magnitude EK.

4. Other Critical Information

  • Unique traits:
    – Deletes Windows Event Logs older than 7 days (wevtutil cl *) to hinder forensics.
    – Uses alternate NTFS streams (ADS) to hide ransom note (:readme.txt)—not visible in File Explorer.
  • Broader impact:
    – Hospitals and county governments reported 22 % of total infections; ICUs in Italy forced to divert ambulances.
    – ISO 27001 regressions: btix exfiltrates ~1 % of data to Mega.co.nz first; expect concurrent breach reporting under GDPR & HIPAA.

Action Checklist (tear-off for incident response rooms)
[ ] Confirm .btix extension & ransom note “ReadMe_Help.hta”.
[ ] Pull network cable / disable NIC.
[ ] Search for scheduled task \btix\bgTask.
[ ] Launch Windows Defender Offline scan on isolated host.
[ ] Check VSS/backup: is immutable set? If yes—begin restore.
[ ] Report to national CERT for potential decryptor.

Stay safe, stay patched.