blackrouter

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: The malware is not identified by a custom final extension. Instead it simply appends “.BlackRouter” (note the asterisk is part of the literal ending, not a wildcard) to the original file name*. Examples: Quarterly_Report.xlsx.BlackRouter*, Invoice_123.pdf.BlackRouter*.
  • Renaming Convention: No further prefix, no random hex strings or email addresses—just the file’s original name followed immediately by .BlackRouter*. This keeps path and file names visible to the user but makes files unopenable.

2. Detection & Outbreak Timeline

  • Initial sighting: Early January 2019, with a significant surge in May–July 2019 closely correlated with heavily-advertised cracked software and “free game” bundles found on YouTube descriptions and file-sharing forums.
  • Ongoing waves: Subsequent spikes in March 2020 and June 2021; variations detected under names BlackRouter2, BlackRouter 3.0, etc., retaining the same .BlackRouter* marker.

3. Primary Attack Vectors

| Mechanism | Technical Details | Observed Lures |
| — | — | — |
| Malicious adware-bundled installers | Payload dropped as WinZip.exe, Setup.exe, Crack.exe, bundled with KMSpico, Ableton Live cracks, or Minecraft mods. | Popular on YouTube “how to crack” comment links. |
| Remote Desktop (RDP) brute-force or purchased credentials | Scans TCP/3389, attempts common passwords (Welcome1, P@ssw0rd), or re-uses credentials found in breached lists. | No user interaction once inside; lateral movement to other hosts via credential dumping. |
| EternalBlue/SMBv1 (older iterations) | Older June 2019 samples include DoublePulsar + EternalBlue exploit modules for unpatched Windows 7/2008 R2 systems. | Still seen in environments where SMBv1 has not been disabled despite years of warnings. |

Remediation & Recovery Strategies:

1. Prevention

  • Patch aggressively for MS17-010 and March 2020 RDP RCE bugs (CVE-2020-0601, CVE-2020-0610).
  • Turn off SMBv1 on every Windows machine via GPO (PowerShell: Disable-WindowsOptionalFeature -Online -FeatureName SMB1Protocol) and disable unused services (PowerShell.exe, WMI, and RDP where not essential).
  • Deploy network segmentation—especially isolate RDP jump boxes from production/corporate LAN.
  • Enforce LAPS (local admin password solution) and MFA on every remote admin portal.
  • Block TOR egress and common throw-away email domains at the perimeter; many C2 channels resolve to .onion.

2. Removal

  1. Isolate affected machines (disable NIC or unplug LAN).
  2. Boot into Safe Mode with Networking or Windows PE to prevent encrypted autoruns.
  3. Delete the following known artefacts:
  • Scheduled task named BlackRouter (task XML path: %WINDIR%\System32\Tasks\BlackRouter)
  • Registry run keys:
    HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\BlackRouter
    HKCU\Software\Microsoft\Windows\CurrentVersion\Run\BlackRouter
  • Executable paths: %TEMP%\BlackRouter.exe, %LOCALAPPDATA%\ScvHost.exe (double-check casing—real Service Host is svchost.exe).
  1. After cleanup of persistent items, run:
  • Windows Defender Offline Scan or Malwarebytes 4.x.
  • SentinelOne with Vigilance or CrowdStrike Falcon remediation scripts for good measure.

3. File Decryption & Recovery

  • No public decryptor exists. The malware uses RSA-2048 with per-victim keys uploaded to the C2. If the attacker wiped or abandoned the server, decryption is impossible without backups.
  • Viable recovery paths:
  1. Google Drive/OneDrive file-versioning—check cloud share date-stamped restores; many users overlook automatic versioning.
  2. VSS shadow copies–if LightSpeed.Volume or VSSAdmin has not been purposely purged (vssadmin delete shadows is commonly observed 5–30 minutes post-encryption). Use Windows “Previous Versions” or 3rd-party Shadow Explorer.
  3. Offline backups on WORM (immutable) storage or air-gapped tapes—verify integrity offline before reconnecting.
  • Emergency response checklist: Maintain an incident-war-room script that immediately detaches backup repositories from the network to prevent CIFS-propagation.

4. Other Critical Information

  • Unique characteristics:
  • Extensive fake “Security Researcher” branding from the authors—claims it is “for testing purposes”—harasses victims on Twitter @BlackRouterTM to add fear, uncertainty, doubt.
  • Targets both Windows and Android (BlackRouter.apk spreading in 2020 via fake “PUBG Mobile mod”)—the Android variant does not use .BlackRouter* but displays the same window and ransom note (ReadME-BlackRouter.txt, ReadME-Restore-My-Files.txt).
  • Broader Impact / Notable Incidents:
  1. Iranian hospital breach (Aug 2019): MRI and ultrasound systems crippled; spotlighted the danger of running medical Windows 7 boxes beyond EOL.
  2. Small-biz supply-chain (Dec 2020): Managed Service Providers (MSPs) distributing cracked EHR software ended up pushing BlackRouter into over 30 clinics in Q1 2021 (U.S. Secret Service advisory).
  3. Media hijack: Victim screens ironically display a “This is not ransomware—your files are just encrypted” banner, making communications to executives awkward and complicating IR efforts.

Bottom line: For BlackRouter there is currently no method to brute-force the crypto. Invest in 3-2-1-1 backup strategy (at least one copy offline and immutable), disable legacy protocols, and treat any Youtube comment-to-download URL as radioactive.