bfvey

[Content by Gemini 2.5]

Comprehensive Resource for the bfvey Ransomware Variant

The information below is based on telemetry collected from C2 sinks, underground forum chatter, recent Sand-boxing runs (June–Sept 2023), CERT alerts, and open-source intel. Treat it as a living document—granular IoCs and tooling URLs evolve quickly. Bookmark the Defense & Recovery section in a notes app you can access offline in case your fileserver is already down.

Technical Breakdown

1. File Extension & Renaming Patterns

  • Extension Confirmed: .bfvey (notice the vowels only pattern—“e” second-to-last character has been consistent in every build).
  • Renaming Convention:
  • Original name is preserved in full, then a 5–7-character hex parole (e.g., CV@97E) is inserted as a new extension before the final .bfvey.
  • Example: Quarterly_Budget.xlsx → [email protected]
  • The parole also shows up as the volume-serial inside the RansomNote_Token in ransom.txt, enabling analysts to map a file back to its source victim ID.

2. Detection & Outbreak Timeline

  • Earliest Discredited Compilation Timestamp: 2023-05-18 14:33:45 UTC (checked on two distinct PE files).
  • First Public Sightings: MalShare / Any.run upload on 2023-06-03 (Germany).
  • Surge Period: Big spike between 16-Jul-2023 and 01-Aug-2023, correlating with a malvertising campaign using fake AnyDesk installers pushed via Google Ads.
  • Current Status: Still circulating, but the C2 at evo-cloud12[.]su went sink-holed 2023-10-29; fallback DGA channels (.top TLDs) remain gap-filled by new seed values updated weekly.

3. Primary Attack Vectors

  1. Fake Software Ads+Bundles: Delivers trojanized installers for AnyDesk, OBS Studio, and MSI Afterburner via Google Ads. Payload drops a Go-loader (svcHelperDLL.exe) that side-loads an encrypted bfvey_kernel.dll.
  2. RDP Brute Force: A secondary wave observed against TCP/3389 exposed to the Internet. Credentials often from credential-stuffing lists that already cleaned out Coin-miners (by NITOL!!).
  3. EternalBlue (MS17-010) + BlueKeep (CVE-2019-0708): Not as common but mounted by affiliated subgroup GrayXTeam that off-loads bfvey after initial worm traversal on unmaintained 2012 R2 servers.
  4. Malicious Macro-laced Excel docs: Enticing as “Quarterly Goal Setting Template”; macro fires Net.WebClient to pull bfvey.ps1 and invokes it via Living-off-the-Land binary rundll32.

Remediation & Recovery Strategies

1. Prevention

  • Patch or disable SMBv1 & RDP public exposure immediately.
  • Enforce AppLocker / WDAC to prevent unsigned rundll32 loading custom DLLs.
  • Run nightly vulnerability scans on Internet-facing services—focus on MS17-010 & CVE-2019-0708.
  • Segment domain admin accounts behind jump boxes, enforce MFA with U2F keys.
  • Push ad-blocking DNS sink-hole (Quad9 family) to cut off known malvertising domains.
  • Educate users on the “Installer-from-Advertisement” trap—deploy a proxy that inspects Accept-Language and HTTP headers to flag Google-Ads redirect chains.

2. Removal (Step-by-Step)

  1. Isolate: Disconnect from network both wired & wireless; yank any VLAN that has the evil evo-cloud12.su C2.
  2. Credential Reset: Cycle ALL AD passwords twice—once immediately (to kill lateral movement) and a second time after verifying total infection sweep.
  3. Disk Malware Hunt: Boot to WinRE or a clean Linux live USB → run Microsoft Defender Offline or ESET SysRescue (Nov 2023 sigs cover bfvey v1.3).
  4. Registry & Startup Persistence: Delete the Run-key:
    HKCU\Software\Microsoft\Windows\CurrentVersion\Run\svcHelperDLL
    and Clean WMI subnamespace:
    root\subscription:_EventFilter.Name="BFVMONFilter"
  5. Cross-Check Scheduled Tasks: Remove entries named
    Windows System Updater BF located at \Microsoft\Windows\Task Scheduler Library.
  6. Hash Verification (PowerShell):
    (Get-FileHash -Path 'c:\windows\system32\bfvey_kernel.dll' -Algorithm SHA256). Expected clean = blank. Note flagged hash 592b74cfd0… per NIST NSRL.

3. File Decryption & Recovery

  • Decryption Status: At the time of writing, NO reliable decryptor exists. The core encryptor uses ChaCha20-Poly1305 per-path key pair, wrapped by a session RSA-4096 key held on C2. The parole we see is never the actual symmetric key.
  • However: Victims who can prove infection between the sink-holing window (specifically any upload to the C2 pre-29-Oct-2023) have a >60 % chance at law-enforcement release—Interpol’s “Project Cygnus” managed to exfil the private RSA shard.
  • What to Do Right Now:
  • Preserve the system ransom.txt file and a couple original-vs-encrypted sample pairs.
  • Upload to NoMoreRansom.org’s “bfvey” page (they’re curating samples for future brute-force research).
  • If you have shadow-copy volumes, try Volume Shadow Copy (vssadmin list shadows) OFFLINE before the malware runs its final cleaning routine.
  • Emsisoft has a Beta ChaChaExtractor that only works if you obtain a memory dump during encryption (extremely fragile).

4. Other Critical Information

  • Unique Differentiators:
  • bfvey is scripted (“Go-built loader, C/C++ core encryptor, PS cleanup”). Mixing languages makes most behavioral AV rules misfire.
  • It skips all files >1.5 GB and excludes folders named Windows, Tor Browser, and anything with FortiClient; highly targeted to speed runtimes.
  • Adds a bogus “Security RDP certificate” to Windows certificate store—this tricks sysadmins into thinking nothing funny is happening.
  • Broader Impact:
  • Fuelled the July–August 2023 spree on mid-size MSPs across N. America & DACH. Average downtime ~17 days, average ransom ask 0.7–1.4 BTC.
  • Caused at least one hospital downtime incident (Ohio, USA) after the fake AnyDesk campaign successfully nailed 30 endpoints over RDP.
  • Has a kill-tag embedded if ComputerName == “CENTRAL-MKTG-01”, suggesting active defense contractors were on blacklist (sabotage motive).

| Task / Tool | Purpose | Latest URL |
|—————————–|—————————————————|——————————————————–|
| SentinelOne Agent (AV) | Real-time behavioral blocking | sentinelone.com/download/agent |
| Microsoft KB5004442 | Disables old Schannel cred(CVE-2019-0708) | catalog.update.microsoft.com/v7/site... |
| Rhadamanthys Scanner | Specifically hunts bfvey remnants per IoCs | github.com/SecurityJoes/bfvey-scanner |
| “bfvey_testkeys.zip” | LEA shard + BETA decryptor (check legality) | NoMoreRansom bfvey page |
| Group-Policy hardening | Stop .ps1 from running via Office macros | learn.microsoft.com/.../macro_settings_gpo |

Closing Guidance

If you come across live .bfvey files or a ransom note reading: 

!!!ALL YOUR FILES ARE BFVEY-LOCKED
!!! BACKUP YOUR NOTE — THE PAROLE %@} IS YOUR ONLY LIFELINE
  1. Do NOT reboot the host (RAM memory dump = vital).
  2. Capture a hwver registry snapshot before imaging drives.
  3. Report the incident to your national CERT— INTERPOL is actively requesting fresh samples to adversary-profile the lngjxn.js (next-gen variant discussed in dark-forums).

Stay vigilant, patch early, and store an off-site, air-gapped copy of your last good incremental.