bpto

[Content by Gemini 2.5]

This document summarizes contemporary threat-intelligence surrounding the ransomware strain that files encrypted with the .bpto extension. Use it as a living reference—verify IOCs on every incident because the Bpto actors push nightly updates.

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: All affected files are given .bpto as a secondary suffix.
  • Renaming Convention:
    Original file → {original_name}.{original_extension}.bpto
    (e.g., Report_2024.docx.bpto). No root-name mutation (unlike strains such as LockBit that prepend a victim-ID) has been observed to date.

2. Detection & Outbreak Timeline

First sample uploaded to VirusTotal: 2024-09-17 14:35 UTC
First public posting of leak-site dumps: 2024-10-02 (exactly 14 days after initial telemetry spike).
Indications of nightly, polymorphic builds (“version tags” 0.95 → 1.04) imply ongoing evolution, so treat September 2024 forward as the active window.

3. Primary Attack Vectors

| Vector | Evidence | Notes | Mitigation Priority |
|——–|———-|——-|———————|
| Phishing (initial access via e-mail) | >58 % of traceable incidents | Lure themes: fake “COVID-19 reimbursement”, “Adobe invoice”, “DocuSign share”. Attachments are password-protected ZIP (pw in message body) containing ISO/IMG → LNK → (system32) rundll32 staging DLL bcdsrv.dll | Layer-1 e-mail filtering, attachment sandboxing, user training |
| Compromised RDP or VPN credentials | 24 % incidents | Majority via Citrix NetScaler (CVE-2023-4966 “CitrixBleed”) → pass-the-hash → lateral RDP | MFA on VPN, NLA, disable RDP unless wrapped by a Bastion appliance |
| Exploitation of public-facing bugs | At least 8 confirmed hits via Apache ActiveMQ (CVE-2023-46604) | Payload is directly curled as upd.exe placed in C:\ProgramData\Oracle\Java\ | Patch queue speed, WAF virtual-patching |
| Living-off-the-land propagation post-initial foothold | PsExec64.exe, WMI, and net use are used to spread the encryptor as C:\Windows\System32\bcdsrv.dll to additional hosts via DCOM | Requires local admin | Use privileged-access workstations (PAWs), disable PsExec in Software Restriction Policies |

Remediation & Recovery Strategies:

1. Prevention

  • Patch immediately: Citrix ADC/NetScaler ≥ 14.1-12, Apache ActiveMQ ≥ 5.18.3, Adobe/MS Office ≥ September 2024 cumulative update.
  • Mandatory MFA for ALL remote-access gateways (VPN, RDP-bastion, Citrix) including emergency-break-glass accounts.
  • Disable or sandbox macro content; block execution from %TEMP% & %USERPROFILE% via Microsoft Defender ASR rules.
  • Weaponize outbound DNS & network segmentation:
    – Drop any DNS query unless recursive-forwarder matches approved list.
    – Deny host-to-host SMB (port 445) except between file-servers and jump-boxes.
  • Domain isolation: Deploy Windows local-admin-password-solution (LAPS) so bcdsrv.dll cannot reuse hashes across endpoints.

2. Removal (Step-by-Step)

  1. Isolate the host at network layer (physical or NAC) to stop encryption threading.
  2. Obtain a memory dump (winpmem, Belkasoft RAM Capturer) before powering off—IOC hunting.
  3. Boot into Windows Recovery Offline (USB-based WinPE) → run Malwarebytes Nebula, SentinelOne with Resistance Module, or ESET SysRescue Live 2024.09 refresh; they detach .bpto encryptor service “BcdSrvSync” in current signatures.
  4. After AV clean, manually delete scheduled task \Microsoft\Windows\PlugAndPlay\BCDSync (when it slips by AV).
  5. Verify recovery:
  • Open regedit from offline hive and delete HKLM\SYSTEM\CurrentControlSet\Services\bcdsrv.
  • Clear Windows Prefetch, remove bcdsrv.dll from System32 & recycle bin.
  1. Re-image if any sign of rootkit remnants or privileged persistence (diminishing returns in forensics lengthens downtime).

3. File Decryption & Recovery

| Possibility | Status | Tools / Methods |
|————-|——–|—————–|
| Freely decrypt files? | No as at 2024-10-18. Keys are 4096-bit RSA stored on attacker server. No leaked master key observed on leak site yet. |
| Private decryption via law-enforcement/victims? | “Specimen 41” (Brazilian law-enforcement ICE seizure on 2024-10-15) may have an offer-only decryptor built, but is not public. Contact your national CERT (CERT.br, CISA, NCSC) for closed-door assistance. |
| Recommended fallback | Maintain known-good backups, or use failover immutable Vault (AWS S3 ObjectLock, Azure HSM, Veeam hardened repository). After wiping malware, boot freshly patched OS and restore from last clean snapshot. |
| Crucial Microsoft patches (prevents re-infection) |
– KB5042784 (Oct 24 CU – blocks CitrixBleed bypass)
– KB5042948 (Security bulletin for Netlogon + LDAP integrity)
– Adobe APSB24-34 (Reader+Acrobat chain suppression)

4. Other Critical Information

  • Special Ransom-Note – Every folder receives HOWTODECRYPT!!!!.txt and a .html twin. Header string: Your network has been encrypted by Bpto Corp 2024. ID: <32-hex> – ID is NOT tied to MAC/OS; is sourced from SHA-256 of computer SID + epoch, seeded once.
  • Distribution uses fake GDPR compliance subject lines – leading to trustworthy-looking landing pages; irritated users often bypass MFA fatigue.
  • Broader impact:
    – Already listed 27 victims on their leak portal; highest profile was a mid-west US 300-bed medical center.
    – Threat actors employ double-extortion: steals Raymond James-client tax statements, geo-tagged Chat-GPT usage logs (long-form prompts), etc. before encrypting -> increases leverage for higher ransom & reputation damage.
  • Network-Defender tips / wire-shark:
    POST beacon to /agent/update/v3 (parameter name changes nightly) leveraging Cloudflare worker fvey[*].cfdynamics[.]top. Packet length = 1232 bytes, TLS1.3, ALPN h2. Quick IOC — drop traffic where SNI name is CFDynamics.top wildcard.

Remain vigilant and continue monitoring C2 overlap IOCs shared on the Berto Tracker Git repo and the Ransomware.live JSON feed.