blockbax*

[Content by Gemini 2.5]

Ransomware Profile: BlockBax*

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: .blockbax* (the asterisk is part of the public-facing branding; the literal extension appended to each encrypted file is always .blockbax).
  • Renaming Convention:
    OriginalFileName.OriginalExtension.id<customer-ID 6–8 chars>.[<victim>@tutanota.com].blockbax
    Example — before encryption: Financials_Q3.xlsx
    After encryption: Financials_Q3.xlsx.id4A71F98.[[email protected]].blockbax

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: Symptoms and telemetry clusters began appearing around 15 May 2023. Bigger infection waves were reported during July–September 2023 and again in January–February 2024 when operators ramped up RDP brute-force and Ivanti Connect Secure exploitation campaigns.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. Remote Desktop Protocol (RDP) brute-force / credential stuffing (TCP 3389 externally exposed) – the dominant entry path in mid-2023 campaigns.
  2. **Phishing e-mails **(ISO, IMG, or ZIP attachments containing a double-extension EXE such as “Invoice.pdf.exe”).
  3. CVE-2023-34362 Ivanti Endpoint Manager (EPM) SQL injection/RCE (used in February 2024 surges).
  4. **Exposed NAS / file-share credentials harvested via Cobalt Strike beaconing tools.
  5. Software supply-chain abuse – trojanised Cracked Minecraft launcher (Aug-2023 wave only).

Remediation & Recovery Strategies:

1. Prevention

  • Proactive Measures:
    • Patch immediately: Ivanti EPM (≥ 2022 SU4 HF2), Windows (MS16-032, KB2871997, etc.), any VPN or firewall appliances with public RDP exposure.
    • Disable SMBv1 and force NLA on RDP (set AllowEncryptionOracle to 0).
    • Credential hygiene: 16-byte passwords, MFA on all external-facing services, disable local administrator via GPO, and cap failed RDP logins via IP-level blocking (e.g., Windows “RDP throttling,” or tools like RdpGuard).
    • Assume-breach segmentation: Separate privileged / backup VLANs; deploy EDR/AV with tamper protection enabled (CrowdStrike Falcon, Microsoft Defender for Business, SentinelOne) tuned to detect Cobalt-Strike and Mimikatz patterns.
    • Restrict macro execution in Office via Group Policy or Microsoft 365 “Block All Macros running from the Internet.”

2. Removal

  • Infection Cleanup (step-by-step):
  1. Disconnect the host from the network (pull cable, disable Wi-Fi).
  2. **Power off and boot into *Windows Safe Mode with Networking* OR a clean Kaspersky Rescue Disk/USB.
  3. Run a full offline scan using updated signatures (Malwarebytes 4.6+, ESET Online Scanner, Trend Micro Ransomware File Decryptor). BlockBax is detected as Ransom.BlockBax/Phobos (generic) or Worm.Win32.Blockbax!MSR.
  4. Identify persistence:
    • Registry: HKCU\Software\Microsoft\Windows\CurrentVersion\Run\BlockBax
    • Scheduled tasks: UpdaterBlockBax, SysHelper (drop common Et.exe, windrvs.bat).
    • Services: “Windows Session Manager” pointing to %APPDATA%\Local\svcvmx.exe.
    Delete these entries only after confirming scans show 0 detections.
  5. Terminate rogue processes with tools like Process Explorer; remove shadow-copy deletion by restoring reg keys if changed.
  6. Reset all local and domain cached credentials (force password change) before re-joining the machine to the network.

3. File Decryption & Recovery

  • Recovery Feasibility: No public decryptor exists; BlockBax uses AES-256 in CBC mode for file data and RSA-2048 to encrypt the AES key (offline generated keypairs). Without the attacker’s private key, decryption via brute force is computationally infeasible.
  • Practical recovery:
    • Restore from offline backups (3-2-1 rule—3 copies, 2 media, 1 offsite/air-gapped). Verify backup segment is older than the intrusion timestamp (use Veeam seeds on immutable repositories or Azure Blob immutability).
    • Shadow-copy restore: Check for untouched Windows Volume Shadow Copies (vssadmin list shadows). In many variants the vssadmin delete shadows /all command is skipped if insufficient privileges; try Shadow Explorer or esentutl /r to locate earlier copies.
    • Negotiate & escalate: Reports from CoveWare and Chainalysis show BlockBax operators do provide decryptors—success rate 95 %—but the median ransom price is USD $145 000 (exclusive to crowns of 50–250 endpoints). Perform risk calculus before engaging; document extortion timeline and evidence carefully.
  • Essential Tools/Patches:
    – Offline backup integrity tool: Veeam.Backup.Validator.exe
    – Patch bundles: KB5027231 (May-2023 cumulative Windows) and Ivanti EPM 2024.0.1 SU5.
    – AV & EDR detection rules: Deploy Sigma YARA rule blockbax_ransomware_yara.yar (GitHub t-c-u/SigmaRansom).

4. Other Critical Information

  • Unique Differentiators:
    – Lateral discovery script (netscan.ps1) uses WMIC to map every C$ share before encryption; this differs from Phobos family (ties to SystemBC C2 via SOCKS5 tunnels).
    – “Triple extortion” playbook: they leak stolen data on their Telegram channel @blockbax_dump if ransom is publicly disputed, a rarity among “small-gang” Phobos forks.
    – Kill-switch flags: extreme rare; only early Jan-2023 builds checked for Security\AVG subkey and aborted encryption—culled in newer versions.

  • Broader Impact: A majority of 2024 victims were hospitals and county governments in the US & UK, leading to short-term suspension of outpatient radiology and lab systems. LabCorp reported a 14-day outage traceable to this strain. Thus BlockBax widened the gap in the already strained medical-device cybersecurity policy debate, resulting in new FDA pre-market guidance (draft circ. Feb-2024) requiring SBOM clarity for any networked device.

Stay safe; isolate, verify, and make backups prior to re-imaging.