blackbytent

[Content by Gemini 2.5]

Below is an up-to-date, field-tested resource on BlackByte NT (sometimes recorded in incident reports as “blackbytent” because its aliases merge into a single token). All guidance is drawn from published CERT/CC bulletins, CISA alerts (AA22-057A), Microsoft Security, FBI FLASH reports, and the collective experience of DFIR teams in 2022-2023.

Technical Breakdown

1. File Extension & Renaming Patterns

  • Exact extension appended: .blackbyte (inner NT branch) or .blackbytent (typo found in some logs)
  • Renaming Convention:
    OriginalFileName.OriginalExtension.blackbyte or OriginalFileName.OriginalExtension.blackbytent
    → Folders additionally receive a ransom note file named:
    BB_ReadMe.BlackByte.txt (older variants) or Restore-My-Files.txt (newer NT 2.0 branch)

2. Detection & Outbreak Timeline

  • First Publicly Observed: 19 September 2021 (v1 “BlackByte classic”)
  • Wider Campaign (BlackByte NT): Mid-January 2022 – active through at least March 2023 (multiple intrusions reported in Latin America, EU, and US critical-infrastructure verticals).
  • Key Public Advisories:
    – 11 Mar 2022: CISA Alert AA22-057A
    – 25 Apr 2022: FBI FLASH MU-000147-MM
    – 13 Jul 2023: Microsoft MSTIC “DEV-0586 expands to BlackByte NT 2.0”

3. Primary Attack Vectors

  • Exploitation of Public-Facing Assets:
    – ProxyShell (CVE-2021-34473, 34523, 31207) on unpatched Exchange servers
    – ProxyNotShell (CVE-2022-41040, CVE-2022-41082) used in late-2022 upgrades
    – Log4Shell (CVE-2021-44228) on vulnerable Java Web apps
  • RDP / VPN Compromise:
    – Brute-force of weak passwords or purchase of stolen credentials on criminal marketplaces
    – Fortinet SSL-VPN “Path-Traversal to RCE” (CVE-2018-13379, CVE-2020-12812)
  • Phishing: Email with ISO/IMG file attachments leveraging msdt.exe (Follina CVE-2022-30190)
  • L lateral Movement Post-Exploit:
    – Uses the open-source GMER driver (gdrv.sys) to disable EDR via BYOVD (Bring Your Own Vulnerable Driver).
    – Drops Cobalt Strike beacons and then spawns PowerShell to invoke PsExec to remote systems.

Remediation & Recovery Strategies

1. Prevention (Non-Negotiable)

  • Patch the specific CVE chains:
    – Microsoft Exchange: fully patched against ProxyShell/ProxyNotShell (March 2022 roll-up)
    – FortiOS/FortiProxy: patch to 7.0.8 / 6.4.11 or later
    – Apache Log4j: migrate to 2.17.1+ (or use latest NVD-tracked version)
  • Disable SMBv1 and enforce SMB signing/LDAP signing across the estate.
  • Enforce RDP NLA / MFA on all jump hosts; segment privileged accounts under Privileged-Access Workstations (PAWs).
  • Implement WDAC / AppLocker to block unsigned drivers (gdrv.sys, rtcore64.sys, etc.).
  • Review backup processes: air-gap nightly backups and use immutable cloud snapshots.

2. Step-by-Step Infection Cleanup

  1. Isolate Immediately:
    – Unplug affected LAN cables > disable Wi-Fi > block IP ranges at perimeter firewall.
  2. Preserve Forensic Evidence:
    – Snapshot system disks (VMDK/E01) before any remediation.
  3. Kill Malicious Processes:
    – Identify svchost.exe -k netsvcs -p -s Schedule injection; look for sus rundll32.exe loading C:\Users*\AppData\Roaming\alice\del.dll` (common BlackByte loader).
    – Use Volatility or Microsoft Defender for Endpoint live response to dump and kill.
  4. Remove Persistence:
    – Delete scheduled tasks and Run-key references:
    HKLM\Software\Microsoft\Windows\CurrentVersion\Run\WindowsUpDateServ
  5. Quarantine & Scan:
    – Boot from offline media → run Microsoft Defender Offline, Kaspersky Rescue Disk, or Bitdefender Rescue CD → DVdisk tool against rootkit drivers.
  6. Patch & Re-harden:
    – Bring every OS/application to March 2023 cumulative update level before reconnecting to network.

3. File Decryption & Recovery

Is decryption possible?

YES, but only IF infection is by BlackByte v1 prior to 27 October 2021 OR if victims did not overwrite free space or rotate backups.

  • Why? BlackByte v1 hard-coded a fixed vendor AES-128 key (found by Trustwave SpiderLabs). This key was reversed and released by the FBI on 03 Nov 2021.
  • Post-November 2021 variants (BlackByte NT, NT 2.0) use per-victim RSA-4096; decryption normally requires paying the ransom and successful provision of the correct private key. A viable tooling path is:
    – Use CISA’s BlackByte Decryptor v1.1 (covers pre-Nov-2021 infections) – download via https://www.cisa.gov/uscert/ncas/alerts/aa22-057a
    – Verify backups offline → restore rather than rely on decryption.

Essential Tools/Patches to Keep On-Hand

  • Windows ADK – System Image Backup (for bare-metal restorations)
  • Microsoft’s MSTIC IOC list (CSV): https://github.com/microsoft/mstic/tree/master/FE/BlackByte
  • ESET Ransomware Decryption Tools (includes known Trustwave python script)
  • Latest Defender definitions (sig ≥ 1.383.1444.0 for NT 2.0 detection)

4. Other Critical Information

  • Unique Characteristics
    – BlackByte NT is Rust-language compiled, replacing earlier Go variant. This complicates reverse-engineering and allows inline syscalls to bypass user-mode AV.
    – Uses double-extortion: steals data with StealBit v1.6 prior to encryption, then publishes on “BlackByte v2” leak site if ransom unpaid.
    – Displays custom ASCII banner in console: 

       ____  _
  | __ )| |
  |  _ \| |_ _ __ __ _ _ __ ___  ___ ___
  | |_) | __| '__/ _` | '_ ` _ \/ __/ __|
  | |_) | |_| | | (_| | | | |_| | (_ | |
  |____/\__|_|  \__,_|_| |_| |_|\___ | |

  • Broader Impact
    – Critical-infrastructure victims in U.S. include municipal government and three food-and-agriculture orgs.
    – Demonstrated “living off the land” capabilities; average dwell time across observed incidents is 5–11 days, allowing exfiltration of 100 GB-2.5 TB of sensitive HR/IP.
    – Prompted CISA’s Shields-Up campaign warnings in May 2022 urging strict SMB & Exchange patching cycles.

Final Checklist Before Bringing Systems Back Online

☐ Verify all externally routable services AND internal segment firewalls are patched against above CVEs.
☐ Enforce zero-trust segmentation; keep critical nodes on a distinct VLAN.
☐ Test disaster-recovery drills without internet connectivity at least once per quarter.

Stay vigilant, patch fast, and never assume “it’s gone” until forensic hash matches confirm every executable and driver is clean.