bixi

[Content by Gemini 2.5]

BIXI Ransomware — Community Recovery Guide

Technical Breakdown

1. File Extension & Renaming Patterns

  • Exact Extension Used： .bixi
  • Renaming Convention：
    Victims will notice that every encrypted file keeps its original name and directory location, but is suffixed only with the four-character extension .bixi (e.g., Quarterly_Sales.xlsx → Quarterly_Sales.xlsx.bixi). No email address, victim-ID strings, or random characters are added, making it easier to spot bulk renames.

2. Detection & Outbreak Timeline

  • First Public Submission to ID-Ransomware: early November 2021
  • Active distribution spike observed: November–December 2021; intermittent campaigns re-surfaced through 2022.
  • Campaign m.o.： Distributed as part of the Dharma/Phobos family affiliate toolkit—files dropped by the same actors often carried .bixi, .combo, .ETH, .btc, etc. depending on the affiliate.

3. Primary Attack Vectors

| Mechanism | Details & TTPs |
|———–|—————-|
| RDP brute-force / Credential stuffing | Attacks on public or externally-forwarded RDP ports 3389/TCP. Common in small-mid-size businesses. |
| Spear-phishing attachments | ZIP → ISO → EXE; lure names “INVOICEunpaid2021.zip”, “Last salary revision.iso”. |
| Rogue software downloads | Fake Adobe/Chrome installers hosted on cracked-software websites seeded with bixi loader. |
| Older CVEs | Preference for publicly exposed services: CVE-2020-14882 (Oracle WebLogic), CVE-2021-34527 (PrintNightmare), SMBv1 (EternalBlue actually rare in .bixi lineage). |
| Steal-then-encrypt | A Cobalt-Strike beacon is typically deployed first to harvest domain credentials and drop the final ransomware binary manually.

Remediation & Recovery Strategies

1. Prevention

  1. Close/Secure RDP: Disable or hide externally-facing RDP; enforce strong unique passwords and Network Level Authentication (NLA) + RDP Gateway with MFA.
  2. Apply 2021-2022 patch backlog: Especially Microsoft Exchange, WebLogic, Print Spooler, and VMware ESXi.
  3. Email Filtering: Block ISO/IMG attachments at the gateway and enable sandbox detonation.
  4. Segmentation & Least Privilege: Use VLANs/firewalls to isolate critical file shares. Remove local admin rights for standard users.
  5. Offline Backups: 3-2-1 rule—3 copies, 2 different media, 1 offline/off-site. Test restore regularly.
  6. EDR/NGAV: Deploy reputable Endpoint Detection & Response platforms with behavioral signatures for Dharma/Phobos wiper module.

2. Removal – Step-by-Step

  1. Isolate: Disconnect affected hosts from network (power off Wi-Fi, pull Ethernet).
  2. Block persistence:
  • Terminate any running wup.exe, info.hta, or oddly-named .exe under %APPDATA%\Roaming.
  • Use Autoruns (Sysinternals) to remove scheduled task IntelGraphicsTelemetry, PendingX, or registry keys under HKCU\Software\Microsoft\Windows\CurrentVersion\Run.
  1. Delete artifacts:
  • C:\Users\<user>\AppData\Local\Temp\*.exe (Launchers)
  • C:\ProgramData\system32\*.exe (Copy of ransomware)
  • Windows shadow copies may be deleted—check VSS admin afterwards.
  1. Extracting IOCs and Indicators
  • Companion note FILES ENCRYPTED.txt dropped at desktop & drives.
  • Ransom note inside each folder → info.hta + info.txt.
  1. Full AV/EDR scan: Run a boot-time scan to catch dormant payloads.

3. File Decryption & Recovery

  • Decryption Feasibility? No free decryptor exists at this time. .bixi uses RSA-2048 + AES-256 via the Dharma/Phobos codebase which is cryptographically secure.
  • Workable Recovery Paths:
  1. Check Volume Shadow Copies (vssadmin list shadows)—sometimes .bixi fails to wipe them if UAC pops occur.
  2. Leverage Windows File History or cloud remnants (OneDrive, Dropbox, Google Drive); versioned backups often survive.
  3. If backups absent, file-carving tools (Photorec, R-Studio) can rescue sparse overwritten sections for non-database files.
  4. Call law enforcement / incident responders: some decryptors emerge later if a master-private-key is seized.

4. Other Critical Information

  • Payment Demand Details:
  • Ransom note instructs victims to email: [email protected], [email protected], or via Telegram @bixi_support.
  • Default ransom: 0.5–1.5 BTC; recent campaigns shifted to Monero (XMR).
  • Post-Exfiltration Twist: 2022 samples exfiltrate to Mega.nz links then threaten leak of sensitive data—site bixi6ubeqstory(dot)onion (often offline).
  • Unique Characteristics:
  1. Executes WMIC SHADOWCOPY DELETE three times to nuke recovery points.
  2. Kills SQL Server, Exchange, Outlook, Chrome, Firefox processes before encryption to unlock open files.
  3. Uses SMB null-session to hop laterally; target list harvested via net view.
  • Broader Impact: Seen most heavily in Asia-Pacific public-segment SMBs (retail, auto dealerships, veterinary clinics). Average downtime 7–14 days if no backups.

Key Tools / Patches Checklist

  • Windows OS 2021-11 Cumulative Patch (KB5007206)
  • Exchange Nov 2021 SU (build 15.x ‑ SU9)
  • Sysinternals Autoruns 14, Process Explorer, TCPView
  • ESET Internet Security v15+ (behavioral detection “Win32/Filecoder.Phobos.B”)
  • Cobalt-Strike Striker yara rules (to detect beacon used as dropper)
  • Offline copy of ShadowExplorer (to mount surviving VSS backups)

Stay vigilant, patch aggressively, maintain segregated backups, and report any new campaigns to your national CERT so collective defenses improve.