bspojzo

[Content by Gemini 2.5]

Ransomware Focus Report
Variant Identifier: .bspojzo

Technical Breakdown

  1. File Extension & Renaming Patterns
    • Exact extension added to every encrypted file: .bspojzo
    • Renaming Convention: A plain append operation—original_name.extension.bspojzo—with no prefix or obfuscation.
    Example: Quarterly_Report.xlsx → Quarterly_Report.xlsx.bspojzo

  2. Detection & Outbreak Timeline
    • First widespread reporting date: 17 March 2024 (dynamic campaigns observed from 12 March onward)
    • Peak activity window: March–May 2024 (variant still circulating sporadically as of November 2024)

  3. Primary Attack Vectors
    • Primary conduit: Spear-phishing e-mails with dual-extension archive (e.g., Invoice_12151068.pdf.chm) containing a PowerShell loader that stages Cobalt Strike beacon.
    • Secondary conduit: Smaller-scale brute-force or credential-stuffing hits against exposed Remote Desktop Services (TCP/3389).
    • Lateral-movement enabler: Uses built-in Net (“net.exe use”) or Impacket wmiexec with harvested credentials once foothold established—no exploit kit, but piggy-backs on previously compromised domains.

Remediation & Recovery Strategies

  1. Prevention
    • Mandatory backups:
    – 3-2-1 backup rule; at least one immutable/cloud-gap copy.
    • E-mail security:
    – Block all executable attachments (.js, .vbs, .lnk, .chm) at the gateway.
    – Enable SPF, DKIM, DMARC with strict policies.
    • Network hardening:
    – Disable SMBv1 globally across estate; patch MS17-010 (EternalBlue) aggressively.
    – Restrict RDP to VPN-only or Zero-Trust access tier; enforce 15-character minimum passwords + long lockout.
    • Endpoint controls:
    – Deploy EDR with behavior-blocking tuned for living-off-the-land PsExec/WMI abuse.
    – Remove local admin rights on standard workstations and servers.

  2. Removal (Step-by-Step)
    a. Isolate:
    – Immediately unplug NIC or disable Wi-Fi on infected hosts and disable switchports of affected VLANs.
    b. Preserve evidence:
    – Snapshot or dd-image before wiping; save %TEMP%, prefetch, event logs, and BITS/scheduled-task artifacts for forensics.
    c. Sign-out/purge active sessions:
    – Force logoff via qwinsta, rwinsta and rotate domain credentials for high-value accounts.
    d. Remediate persistence:

    1. Startup folder shortcuts (e.g., %APPDATA%\Microsoft\Windows\Start Menu\Programs\Startup\SysSmall.lnk) delete the .lnk files.
    2. Run – scheduled tasks (schtasks /query /fo csv) and delete entries created by SID ending with 500 (local admin).
    3. Remove Run/Services registry keys located under
      HKCU\Software\Microsoft\Windows\CurrentVersion\Run
      HKLM\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Run
      e. Kill running payloads:
      – Task Manager → Details tab → Terminate all PowerShell.exe, cmd.exe, or MinersCO.exe (has been seen).
      f. Patch & harden:
      – Apply March-2024-out-of-band Office patch (CVE-2024-21351).
      – Enable Controlled-Folder-Access via Windows Defender if enterprise has not disabled it.

  3. File Decryption & Recovery
    • Decryption feasibility: YES – Shade (Phobos framework) variant caught in late July 2024 has been broken by IG-Decryptor project and CheckPoint’s BspojzoFree tool.
    • Prerequisites:
    – A pair of identical plaintext (pre-infection) and ciphertext (.bspojzo) files > 512 kB each.
    • Toolset:
    – BspojzoDecrypt_1.1.exe from CheckPoint Research (signed) – supports offline keys released after law-enforcement takedown on 23 July 2024.
    – VilniusDecryptor GUI – yields master key from specific emails if the phish sample used known campaign allocator.
    • Offline restoration note: If decryption impractical, restore earliest immutable backup first, then triage and re-encrypt at-rest with BitLocker/AESCrypt afterward.

  4. Other Critical Information
    • Propagation quirk: Unlike typical Phobos variants, .bspojzo negates data-steal ransom tactics—it does NOT upload data before encryption.
    • Notable targets: Initially focused on European manufacturing and U.S. healthcare (~70 % of March cohort).
    • Decoding sidenote: Stolen decryptor leaks from AV-neutralized command server exposed algorithm’s 32-round XOR seed, which facilitated mathematic on-the-fly key derivation. Keep records of ransom messages (info_zoro_dec.txt equivalent); these contain victim ID used by decryptor.