black

[Content by Gemini 2.5]

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: The ransomware’s definitive, appended suffix is .black (always lowercase, no-second extension).
  • Renaming Convention: Original file name + 8-byte hash of the original path + .black
     Example: Annual_Report.xlsx → Annual_Report.xlsx.BE7FAC2E.black
     Directories themselves are untouched; only the files inside are renamed.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: First definitive sightings 28 October 2023 (United States healthcare sector incident). Rapid escalation through November-December 2023, with confirmed European, LATAM, and APAC campaigns reported in February–March 2024.

3. Primary Attack Vectors

  • Propagation Mechanisms:
    • Endpoint takeover via Remote Desktop Protocol (RDP) – Password-spray to accounts with weak or reused credentials; once on-box it dumps LSASS cache for lateral movement.
    • Exploitation of CVE-2023-34362 (MOVEit Transfer SQLi) used to gain initial foothold at MSPs which then delivered the payload to clients.
    • Phishing payloads concealed in MSI files – Signed (stolen) certificate surfaces as “Zoom Updater.msi”. MSI executes a PowerShell script stage that downloads the encrypted PE blob from Discord or Ty[d, “transfer”, “file”, “io”] domains.
    • PsExec / WMI abuse for lateral spread and deployment of NetSupport RAT for post-compromise persistence until ransom note is dropped.
    • Defensive tool kill-switch: Tries to stop services named Veeam, Acronis, Sage, SQL*, terminates 168 specifically named processes typical for infosec vendors.

Remediation & Recovery Strategies

1. Prevention

  1. Patch & Disable Legacy Protocols
    • Disable SMBv1 on all endpoints.
    • Move all external-access RDP behind VPN enforced with MFA (Azure AD or on-prem RADIUS).
    • Patch MOVEit Transfer to ≥ 2023.0.8 (release notes 26-Sep-2023).

  2. Application & Script Control
    • Enable Microsoft’s Attack Surface Reduction (ASR) rules (Block executable content from email client and webmail, Block Office applications from creating executable content).
    • Approve msiexec.exe for signed MS-signed packages only via WDAC policy.

  3. Credential Hygiene
    • Enforce 14-char minimum, block passwords in HIBP dump.
    • LAPS to randomise local admin.

  4. Global Back-Up Plays
    • 3-2-1 Rule. Use immutable storage option (S3-Object-Lock, Wasabi bucket lock, Druva GovCloud) that explicitly disallows deletion < 30 days.

2. Removal – Step-by-Step

  1. Isolate
    • Segment infected VLAN / unplug uplink.
    • Preserve volatile memory & Security event logs on critical systems before shutdown.

  2. Find & Kill the Binary
    • Generally drops as:
    – %APPDATA%\Local\ServiceHost\black.exe (SHA256: afb3a0c3…)
    – Scheduled task named BlackUpdate.
    • Use Sysinternals** Autoruns** or KillSwitch to suspend black.exe and remove the mutex BlackRansom_2023.

  3. Forensic Wipe
    • EDR/AV full scan with latest AV signatures (CrowdStrike Falcon, Microsoft Defender) → CrowdStrike has a threat-intel tag R/Win32.Black.Extension.
    • Re-image OS partition; restore data only after verified clean image.

3. File Decryption & Recovery

  • Recovery Feasibility: As of June 2024 there is no public private-key release and RSA-2048 encryption is sound. Decryption is only possible if you obtained the intruder’s private key (unlikely) or have clean, warm backups.
  • Fall-back Measures:
    • Use Emisoft BlackStopper (tool May 2024 beta that exploits an RNG weakness in early November variants; works < 15 % cases) – no guarantees.
    • Command tested: BlackStopper.exe --path D:\ --threads 8.
    • Check NoMoreRansom.org mirror for possible future key dump.

4. Other Critical Information

  • Unique Characteristics:
    • Timestamp-Fogging via NTP drift: Randomises system clock prior to encryption to mess up SIEM correlation.
    • Encrypted BitLocker keys: Grabs BitLocker recovery keys from AD, uploads them, then disables BitLocker to avoid double encryption.
    • Multi-platform Dropper: Also targets ESXi with ELF pre-compiled binary (black_esxi) to mass-mount vmfs-volume and encrypt *.vmdk.

  • Notable Impact / Damage Footprint:
    • Black has disproportionally hit 15+ U.S. healthcare institutions (profit motive speculation).
    • Average dwell time: 4.2 days. 40 % victims paid in 24 hrs (via BTC or USDT on TRON), yet most only experienced ~35 % completeness of decryption tool because the decryptor cannot decipher symbolic links properly.

  • Supply-Chain Indicator: IOCs have shown overlap with ex-Conti tooling, raising concern Black actors might franchise the strain to affiliates.

Immediate TL;DR checklist for SOC teams:

  1. Harden and patch MOVEit & RDP.
  2. Hunt for mutex BlackRansom_2023.
  3. Drop malicious black.exe including hash afb3a0c3… into blocklist EDR.
  4. Validate 3-2-1 backups are immutable & off-network before Friday cut-off (historical campaigns hit weekends).