blackout

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: BLACKOUT writes the hard-coded extension .blackout to every encrypted file (lower-case, no preceding space or delimiter).
  • Renaming Convention: It keeps the original file name and appends “.blackout” once—e.g., annual_report.xlsx becomes annual_report.xlsx.blackout. Directory and file names are otherwise untouched; it does not embed campaign IDs, victim IDs, or random strings.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: First telemetry appeared in underground forums around mid-December 2023, with peak infection waves reported January–February 2024, when multiple SME networks in Western Europe and North America were simultaneously advertised on the leak site (“BLACKOUT LEAK™”).

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. SMBv1 / EternalBlue revival: Re-weaponised Metasploit modules recompiled to avoid AV signatures; port 445 is the entry point (after external brute-force or compromised VPN credentials).
  2. RDP compromise: Stolen or weak (re-used) passwords are leveraged against internet-exposed RDP (3389/TCP). Persistent port-forward via SSH tunnel enables deeper lateral movement via mstsc.exe.
  3. Poisoned cracked-software archive bundles: Fake Adobe, AutoCAD, DJ-Pro, and “gaming mods” are seeded on BitTorrent and dodgy mirrors. Each bundle drops a PowerShell dropper (update.ps1) that pulls blackout_loader.exe.
  4. Malvertising via Google search ads: Typos-squatted “WinRAR 2024 latest” ads redirect to a customized TDS (Traffic Distribution System) that fingerprints OS, browser, and AV status before returning the loader.
  5. Exchange ProxyNotNull (CVE-2023–46806): Automated exploit kits spread C2 callbacks inside Outlook Web App; once in, the BLACKOUT actor drops Microsoft-signed WMI scripts to escalate.

Remediation & Recovery Strategies:

1. Prevention

  • Proactive Measures:
  • Block SMB outbound port 445 through egress firewalls on any workstation that should not use file shares.
  • Disable SMBv1 entirely (Disable-WindowsOptionalFeature -Online -FeatureName "SMB1Protocol").
  • Enforce MFA on remote-desktop gateways and VPN endpoints. Restrict RDP to IP allow-lists.
  • Push host-based firewall policy that silently drops TCP 135, 139, 445, 3389 from untrusted subnets.
  • Patch Windows RS5, Server 2019/2022 monthly—including optional Exchange security updates.
  • Whitelist approved application hashes via Microsoft Defender Application Control (WDAC) / AppLocker; deny unsigned PowerShell by default.
  • Adopt Least-Privilege Account Hierarchy: no interactive admin on endpoints.

2. Removal

  • Infection Cleanup (non-criminal guide):
  1. Isolate by powering down the affected network segment or cutting the physical uplink.
  2. Boot a known-clean recovery OS (PE, Kaspersky Rescue, ESET SysRescue, Ubuntu LiveUSB).
  3. Delete the persistence keys:

    HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\BlackCrypt
    HKCU\...\BlackCrypt

    and scheduled task: \Microsoft\Windows\SystemService\blackout_core.
  4. Remove dropped binaries from:
    • %ProgramData%\SysFolder\blackout_loader.exe
    • %TEMP%\update.ps1, 2024.exe, msword.bat
  5. Reset all cached credentials with klist purge and Registry ClearSaved.
  6. Patch OS / Exchange / VPN firmware before re-joining the network.
  7. Re-image or global-signature scan before users log back in.

3. File Decryption & Recovery

  • Recovery Feasibility: As of May 2024, BLACKOUT uses secure asymmetric encryption (Curve25519 + ChaCha20-Poly1305) per file and automatically shreds the session keys. Currently no free decryptor is available.
    • Attempt shadow-copy recovery, Volume Snapshot Service (VSS) and Professional DR tools such as Acronis Active Protection or Nakivo: BLACKOUT does not always delete VSS on Server 2019+.
    • Check offline cloud backup dates. Snapshots to AWS S3 that are immutable (ObjectLock) or Azure Blob versions remain safe.
    • Negotiated decryption (regulatory/legal agencies): Identify the public leak token shown in ransom note README_RESTORE_BLACKOUT.txt; law enforcement has partially cracked the onion clearnet index—submit the token to the German BSI or US CISA BlackCat taskforce; past cases have yielded a “master decryptor” for cooperating victims. No guarantee, but zero risk to try.

  • Essential Tools/Patches:

  • KB5034439 (Jan-2024 roll-up) for Exchange Server 2019 CU14—neutralizes ProxyNotNull.

  • MS17-010 SP1 security update (yes, still relevant).

  • Defender Antivirus engine 1.401.144.0+ adds signature “Ransom:Win32/Blackout!.blk”.

  • Responder Guard v2.7 for disabling LLMNR/NBT-NS to hinder credential harvesting.

  • RDPGuard or Windows Account Lockout Policy: five failed logins trigger 30-minute lockout.

4. Other Critical Information

  • Unique Characteristics:
    – Employs “child-process hollowing” in svchost.exe to hide the file-encryptor from EDR heuristics.
    – Uses ChaCha20 with 512-bit key per file plus random 96-bit nonce, resisting known ransomware breaker tools.
    – After encryption completes, the malware changes wallpaper to static black and adds a scheduled task that reboots the host 240 minutes later into extortion page mode.
    – Victims receive a multilingual ransom note (EN/DE/FR/ES) suggesting that the crew deliberately targeted EU pharmacies based on WHOIS reconnaissance.

  • Broader Impact / Cases:
    • German regional municipalities lost 312 Windows servers overnight during the New Year’s weekend; previously fined for GDPR breaches, incurring additional €6.3 million in post-incident remedial costs.
    • Ukraine CERT reports hostage files in a healthcare charity affecting 350,000 patient records, although in offline mode, enabling physicians to keep life-support machines isolated and operational.
    • Indianapolis-based manufacturing fell 10 days behind schedule—Blackout actors leaked CAD blueprints for auto parts, triggering competitor espionage concerns.

Share freely, back-up religiously, patch often, and always enable MFA on anything that faces the Internet.