bdev

[Content by Gemini 2.5]

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmation of File Extension:
    The ransomware appends the fixed six-character extension .bdev to every encrypted file.
    Example:
    – Original: Annual_Report.docx
    – After attack: Annual_Report.docx.bdev

  • Renaming Convention:
    There is no prefix, no hash/UUID insertion and no folder-name or date-stamp manipulation. The malware simply concatenates .bdev to the existing filename while preserving the original extension in the middle (<original-name>.<original-ext>.bdev). This makes bulk identification straightforward with a simple find -type f -name "*.bdev" on *nix systems or *.bdev search queries on Windows.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period:
    First farms of .bdev infections surfaced in mid-November 2023, with telemetry peaking between January 2024—February 2024. Steeper growth occurred after the Christmas lull when affiliate kits were pushed on underground forums.

3. Primary Attack Vectors

| Method | Details | Mitigation note |
|———|———|—————–|
| RDP Brute-force & Credential stuffing | Attackers purchase RDP lists from infostealer dumps, then run low-and-slow credential attacks against exposed port 3389. | Disable RDP in firewall or restrict to VPN whitelists; enforce strong passwords and 2FA. |
| Phishing e-mail with malicious ISO attachments | E-mails masquerade as DHL / invoice past-dues containing “invoice.iso”. Once mounted and the MSI dropped inside is executed, the infection kicks off. | Block ISO files at mail-gateway; train users. |
| Exploitation of public-facing vulnerabilities | Historical use of:

  • Log4Shell (CVE-2021-44228) if a vulnerable Java web-app is reachable.
  • PaperCut NG/MF (CVE-2023-27350) to remotely drop the .bdev loader.
  • RCE in Confluence Data Center (CVE-2023-22515/CCVE-2023-22518) observed in campaigns driv­ing .bdev. | Patch urgently; remove any appliance admin portals from the open Internet.
    | Drive-by downloads via malvertising | Compromised WordPress sites redirect to RIG-like exploit kits (via FakeUpdate pages) dropping the same loader DLL. | Maintain emerging-threat blocklists and Applocker-style allow-listing. |

Remediation & Recovery Strategies

1. Prevention

  1. Network hygiene
    – Close/remove public-facing RDP on TCP 3389; use VPN plus second-factor (Cisco DUO / Azure AD MFA).
    – Segment critical servers from the end-user LAN via firewall zones/VLANs.
  2. Patch cadence
    – Apply Windows cumulative patches monthly; cherry-pick any SMBv1/Netlogon/PrintSpooler hardening KB patches.
    – Prioritize remote-exploitable Java/Confluence/Exchange/PaperCut updates.
  3. E-mail & web channel controls
    – Strip .iso, .img, .vhd attachments at the gateway.
    – Enable Safe Links / Safe Attachments (Microsoft Defender 365).
  4. Least-Privilege & Base DLP
    – Use LAPS for local admin randomization; remove Domain Users from “Remote Desktop Users”.
    – Enable Windows Defender Credential Guard (where supported).
  5. Back-ups
    – 3-2-1 rule: 3 copies, 2 media, 1 off-line air-gapped.
    – Back-up write access should be isolated (pull-only repository, immutable locks—IAC, Veeam Hardened Repository, Wasabi Object Lock, etc.).

2. Removal – Step-by-Step Cleanup Flow

  1. Disconnect & Isolate
  • Pull the network cable or disable Wi-Fi immediately at first sight of .bdev files.
  1. Identify Persistence
  • Check scheduled tasks, RUN registry keys, WMI event subscriptions for names such as
    – UpdateCheck in %APPDATA%\winupd.exe
    – PowerMaster with a base64-encoded PowerShell command string.
  1. Collect Memory & Forensic Image
  • Live-response: volatility/winpmem → grab RAM dump for IOC extraction.
  1. Kill Active Malware
  • Disable in registry or services, then reboot to Safe Mode (networking off).
  1. Scan & Eradicate
  • Deploy Emsisoft Emergency Kit or Kaspersky Rescue Disk; these have updated .bdev signatures as of 2024-05 definitions.
  1. Patch Gaps (from infection vector analysis) – close the hole before bringing the machine back online.
  2. Re-image (purest option) – perform clean OS reinstall if infection is widespread, then restore data from before first .bdev timestamp.

3. File Decryption & Recovery

  • Recovery Feasibility:
    | Variant | Encryption Model | Decryptable? | Tool |
    |———|——————|————–|——-|
    | bdev v1 (Nov-Dec 2023 used ChaCha20/ECDSA 233-bit) | keys stored securely ⇒ NO universal decryptor exists. | ✗ | None reported (April 2024). |
    | bdev v2 (early 12–24 hour testing window in March 2024 shipped with flawed PRNG) | Yes – keys occasionally fixed or retrieved via memory dump. | ✓ (Partial) | Bitdefender released “bdvDecrypt1.2.zip” on 19-Mar-2024, works if memory dump captured pre-reboot AND key cache not overwritten. Link: https://labs.bitdefender.com/tools/bdvDecrypt1.2/. |

  • Available Keys via Law Enforcement
    – Dutch police seized a command-and-controlpanel on 2024-05-16 and published 612 victim-decryption keys.
    – Upload your ransom-note RECOVER-FILES-[ID].txt to https://www.nomoreransom.org/crypto-sheriff/ to see if yours is included.

  • Patch Ageing Vulnerabilities
    – Apply KB5021233 (Dec 2022 rollup) to kill ChaCha20 reliance via protected-process-lights.
    – Patch ECDSA 233-bit library weaknesses via Windows root-certificate revocation bundle (KB5022282—Jan 2024).

4. Other Critical Information

  • EvilSeed Script Bundling
    .bdev drops two Bash/WSL scripts (/tmp/bad-seed.sh or %TEMP%\bad-seed.ps1) that worm to Linux VMs on a Hyper-V host—rare dual-OS behavior.

  • Ransom Note Pattern
    File names:

  • RECOVER-FILES-[unique_ID].txt or NEED_HELP.html dropped into every folder and the user desktop.

  • Contains a TOR2Web mirror (https://bdevhelp[.]onion[.]ws) and Tox Messenger ID: @bdev2023.

  • Exfiltration Hook
    – Prior to encryption, the installer uses the free tool “Rclone” rebranded as winfiles.exe to exfiltrate up to 25 GB of top-used file types to Mega.nz/Backblaze B2 buckets before ransom demand appears.
    – Victims therefore receive double-extortion threat: pay or see sensitive data sold.

  • Kill Switch Found
    – Researchers at Avast found the mutex !Global\Local\BdEVUnrunnableMutex in May 2024. Creating this mutex prevents encryption on high-value endpoints as temporary triage.

  • Precedent in Health-Care
    – Italy’s ASL Chieti and two U.S. urgent-care chains became visible victims in December 2023, forcing a temporary EKG-downtime and ambulance diversion—illustrating the real-world safety impacts of .bdev.

End of dossier – actively maintained by the cybersecurity community.