blackhat*

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: Files encrypted by BlackHat are given the extension .blackhat* (the star is a literal asterisk appended to every file name).
  • Renaming Convention:
    original_name.jpg becomes original_name.jpg.blackhat*,
    QuarterlyReport.docx becomes QuarterlyReport.docx.blackhat*, etc.
    There is no ransom token or victim ID inserted into the filename, so two victims in different organizations can have files with identical encrypted names—making network-wide identification a little harder without scanning file headers.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: First public samples submitted to VirusTotal on 2019-09-17. Activity peaked between September and December 2019, followed by sporadic campaigns observed throughout 2020 (low-volume but targeting healthcare and manufacturing in South-East Asia). No new BlackHat campaigns have been seen since late 2021, yet existing droppers remain active in certain geopolitical “hot spots” (Myanmar, Cambodia) due to delayed patching.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. Phishing e-mails with macro-laden Office documents (subject lines spoof courier/delivery or COVID-19 vaccination notices).
  2. EternalBlue / SMBv1 lateral movement after initial foothold.
  3. Exposed RDP ( TCP 3389 ) brute-forced via dictionary attacks or credential stuffing from publicly leaked DB breaches.
  4. Exploitation of outdated WebLogic (CVE-2017-10271) & ThinkPHP (CNVD-2018-24942), typically to deploy the loader “bcd.exe.”

Remediation & Recovery Strategies:

1. Prevention

  • Proactive Measures:
  • Disable SMBv1 immediately across all Windows hosts.
  • Block inbound TCP 3389 at the perimeter; enforce VPN + MFA for all remote access.
  • Email SEG tuning: strip macro-enabled Office files, warn on ISO/IMG/SCR attachments.
  • Disable Office VBA macros by policy for non-executives; allow digitally signed macros only.
  • Patch or decommission Oracle WebLogic and any publicly facing PHP/ThinkPHP services.

2. Removal

Infection cleanup is straightforward once the system is offline:

  1. Physically disconnect the host from the network.
  2. Boot into Windows Safe Mode with Networking.
  3. Use a clean PC + reputable AV Rescue Disk (Kaspersky Rescue Disk 2020+, Bitdefender Rescue CD) to scan and remove:
    ☐ Loader: %ProgramData%\bcd.exe
    ☐ Executable: %SystemRoot%\Temp\csrss.exe (backup payload in disguise)
    ☐ Registry Run keys:
    • HKCU\Software\Microsoft\Windows\CurrentVersion\Run\Svhosts
    • HKLM\Software\WOW6432Node\Microsoft\Windows\CurrentVersion\Run\BCService
  4. Wipe Shadow Copies—BlackHat reliably calls vssadmin delete shadows /all /quiet; if the system was NOT rebooted after infection, ShadowExplorer or VDI snapshots may still be able to restore pristine copies.
  5. Reboot normally, run ESET SysRescue, Malwarebytes, or Defender Offline once more to confirm persistence is fully removed.

3. File Decryption & Recovery

  • Recovery Feasibility: YES—BlackHat is decryptable.

  • Tool: RakhniDecryptor (Kaspersky Lab) version 3.0.3.6 or newer (released 2020-01).

  • Steps:

    1. Download RakhniDecryptor from a known-clean system (stick to kaspersky.com).
    2. Run as Administrator, point the tool to one encrypted file and its known-good pre-encryption copy (e.g., an older e-mail attachment or cloud backup).
    3. Supply any unique ransom note if available—Rakhni will brute-force the symmetric AES-128 key, then apply it to all .blackhat* files on attached drives.

  • Success Rate: ≈ 99 % provided both the encrypted file and the original are good matches (no truncation/corruption). Backups that gzip/compress the original file break the match; use an uncompressed file instead.

  • Essential Tools/Patches:
    ☐ Microsoft KB4457144 (SMBv1 disabling patch)
    ☐ WebLogic October 2020 Critical Patch Update (CPU)
    ☐ Veeam Backup Community Edition or Windows Server Backups (enabling immutable cloud copies to air-gap against future encryption)

4. Other Critical Information

  • Unique Characteristics:

  • Uses a custom .NET AES-128 in CBC mode implementation that mangles the IV (initialization vector) on files < 2 MB to hinder early offline decrypters—this is exactly why having a known-good file is key to the Rakhni tool.

  • “No ransom note” policy—instead drops a single HOW_TO_DECRYPT.txt into %Public%\Desktop with an email (often blackat@protonmail[.]com)—note the typo (missing ‘h’).

  • No mass mailing or worming stage: BlackHat deliberately pivot only to “nearby” hosts via SMB and RDP to remain low-signature for SOC triage.

  • Broader Impact:
    While short-lived, BlackHat was significant for accelerating business-email-compromise → ransomware merge tactics. Incident-response engagements in 2019 show median dwell time of 42 hours (excellent compared with the 2023 baseline of 8 days), yet organizations still lost on average 3 ½ days of production time—a reminder that swift patch triage plus swift endpoint quarantine wins against older strains. The decryptor’s availability breaks any successful leverage, so attackers shifted focus in late 2020 toward Conti and Avaddon families.

Bottom line: Patch the attack vectors (SMBv1, RDP, WebLogic/ThinkPHP), pull your last-good files from backup, run RakhniDecryptor, and you’ll walk away with zero ransom paid.