blackbit

[Content by Gemini 2.5]

BlackBit Ransomware – Complete Defense & Recovery Guide

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: All affected files are appended with “.BlackBit” (exact spelling & capitalization as observed in live incidents).
  • Renaming Convention:
    Original filename → <original filename>.<original extension>.BlackBit
    Example: Q4_Report.xlsx is renamed to Q4_Report.xlsx.BlackBit

2. Detection & Outbreak Timeline

  • Public Emergence: September 2022, strongly linked to leaked/“modded” source code from the LokiLocker family.
  • First Major Wave Noticed: Early-October 2022 (primarily APAC region), followed by multi-continental spikes throughout 2023.
  • Current Gen (v3.4.1) fingerprints: Compiled using Go 1.20, PE timestamp spoofing common.

3. Primary Attack Vectors

| Vector | Details & CVEs | Common Delivery |
|——–|—————-|—————–|
| RDP / Initial Access Brokers | Brute-forced RDP, default/weak credentials; lateral via PetitPotam, Zerologon (sometimes) | Exposed 3389/TCP; cracked by IABs, sold on forums |
| Living-off-the-Land (LotL) PSExec / WMI | Uses legitimate psexec.exe, wmic, powershell, net use | Dropped from $reboot share after domain compromise |
| Phishing – ISO˃LNK˃BAT chain | Email urging “urgent invoice” with .iso attachment → .lnk → .bat | SHA-256: ef655b… (sample from November drop) |
| Software vulns | Commodity exploit kits (ProxyLogon, Log4Shell), initial foothold then BlackBit payload | Fortinet IPS, Exchange history confirm successive attempts |
| Malvertising / Fake Updates | Fake “Chrome/Edge update” landing pages serving BlackBit dropper (update.bat) | Drive-by during specific geo-targeting campaigns |

Remediation & Recovery Strategies:

1. Prevention

  1. Disable inbound RDP externally – force VPN-only access; require MFA + strong passwords.
  2. Patch fast & systematically – ProxyLogon, Log4Shell, FortiGate/FortiProxy (CVE-2023-27997), Windows Print Spooler, Zerologon.
  3. GPO to deny PSExec, WMI remote execution except from limited admin accounts.
  4. Software Restriction Policies & / or Windows Defender App-Control – block %TEMP%\*.bat, %USERNAME%\AppData\Roaming\*.exe, unsigned binaries.
  5. Email gateway rules – quarantine .iso & .img, strip macros, rewrite .lnk targets.
  6. 3-2-1 immutable backups – one copy air-gapped/offline (Veeam hardened repo, immutable S3) with scheduled integrity checks.

2. Removal

  1. Immediate isolation – disconnect NIC, disable Wi-Fi, power off shared storage if possible.
  2. Boot into Safe-Mode or boot disk (Linux rescue), mount security tools (USB).
  3. Scan & Clean
  • Full on-demand scan with updated Windows Defender (detections: Ransom:Win64/BlackBit.A) or reputable EDR (CrowdStrike, SentinelOne, Bitdefender).
  • Manually delete resident persistence:
    • SchedTasks: C:\Windows\System32\Tasks\WinUpdate
    • Service: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WinRing0-1 (BlackBit memory-dump driver)
    • Run keys: HKCU\...\Run\BlackBit = "C:\Users\%username%\AppData\Local\Temp\BlackBit.exe"
  1. Enjoy Safe-mode full AV scan twice, hash-check comparison via PowerShell (Get-FileHash).
  2. Restore normal boot, re-join domain (if domain was infected), force password resets & rotational Kerberos tickets.

3. File Decryption & Recovery

  • Free decryptor available? No – BlackBit uses ChaCha20 for file, RSA-2048 for key; keys stored on C2 (TOR) and wiped locally more often than not.

  • Alternate recovery paths:

  • Shadow Volume Copies restored: BlackBit clears vssadmin delete shadows /all /quiet. Yet, in ~15 % of incidents snapshots survive; run vssadmin list shadows.

  • Stop-saw pattern: If process killed before encryption fully finishes, partial-file carve-out is possible with PhotoRec/QPhotoRec on raw image.

  • Vendor negotiations / law-enforcement: Submit a sample to NoMoreRansom.org & local LE; if LE takedown captures keys an update will be posted.

    🟢 Essential ready-to-use Tools

  • Kaspersky AVZ or TDSSKiller (driver cleanup)

  • BlackBit removal script (current ESET – Aug 2023 sigs)

  • VSS repair tool (rstrui.exe in Safe Mode)

  • Patch Tuesday MSC: KB5028166 (Aug 2023) – LSASS/AD hardening pertinent to BlackBit lateral movement paths

4. Other Critical Information

  • Panel & Negotiation Style:
    Ransom note Restore-My-Files.txt; TOR chat link (blackbit-decrypt.*****.onion). Operators offer 1-sample file decryption “proof” but rarely actually decrypt; DLS leaks on BreachForums if ransom unpaid within 7 days.
  • Unique Signatures (hardcoded string inside binary decryption stub: “You are pawned by BlackBit v3.4 – VOID.#Team”).
  • Language & Docs: Russian/English notes; geo-filtering avoids post-Soviet states (common OFAC indicator).
  • Recommended Severity: Severe – strong encryption, no proven free decryptor; medium-to-large enterprises already targeted. Treat as Tier-1 response protocol.

Final Checklist (Printable)

☐ Patch Exchange & Log4Shell
☐ Disable SMBv1 & unused protocols
☐ Harden RDP: firewall rule + force NLA + MFA
☐ Deploy EDR with ChaCha20 ransomware behavior sensors
☐ Weekly air-gapped backup verifications
☐ Incident-response playbook rehearsed (including call-list to NoMoreRansom & CERT)

Stay safe, maintain backups, and share IOCs to help the whole community.