blind

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: The ransomware now called Blind appends “.blind” to every encrypted file.
    Example: QuarterlyReport.xlsx becomes QuarterlyReport.xlsx.blind.

  • Renaming Convention:
    – Files are encrypted in-place; the original filename remains entirely unchanged except for the single appended suffix.
    – No e-mail address, user ID, or hexadecimal token is inserted in the filename (unlike “.id-[].[@].[]” families).

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: First samples seen August–October 2017, reached peak activity Q4 2017 – Q1 2018 (shortly after the decline of earlier GlobeImposter strains).

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. Remote Desktop Protocol (RDP) brute-force & reuse of stolen credentials
    – Scans for TCP 3389 open to the Internet; uses password-spray or previously-captured credentials from earlier breaches.
  2. Manual lateral movement
    – After initial foothold, attackers pivot via PSExec, WMI, and scheduled tasks, distributing service.exe or enc.exe on every reachable host.
  3. Malicious e-mail attachments (rarer but observed)
    – .ZIP files containing HTA droppers (“Invoice_*.hta”), which then download a second-stage loader.
  4. Exploit kits & watering-hole injection (historical)
    – Tied to RIG EK in 2017; declined as EK usage fell off.
  5. Third-party MSP/RMM tools
    – In incidents where MSPs reused single administrative passwords, Blind was pushed simultaneously to dozens of endpoints.

Remediation & Recovery Strategies:

1. Prevention

  • Proactive Measures:
  1. Block TCP 3389 at the network perimeter or move RDP behind VPN/Zero-Trust access.
  2. Enforce complex, unique passwords and use account lockout policies (e.g., Account lockout threshold = 5).
  3. Deploy MFA on every privileged account (local Interactive & RDP console).
  4. Segment networks to limit lateral movement; disable SMBv1 completely (Blind did not use EternalBlue, but accomplices may).
  5. Application whitelisting / EDR – Restrict PowerShell & PSExec to authorized scripts; ensure EDR can block suspicious .exe launches from TEMP.
  6. Backups 3-2-1 rule – Immutable, air-gapped, versioned snapshots. Blind deletes VSS shadow copies (vssadmin delete shadows /all).

2. Removal

  • Infection Cleanup (Windows Environment):
  1. Isolate the host – power off network or set host firewall to block all outbound except to EDR console.
  2. Boot to Safe Mode + Networking with Command Prompt or from clean WinPE flash-drive.
  3. Delete persistence
    – Registry run keys:

    HKCU\Software\Microsoft\Windows\CurrentVersion\Run\SystemHelp
    HKLM\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Run\SystemHelp

    – Scheduled Tasks named Windows Update Check, Service Manager.
  4. Remove binaries – common locations:

    C:\Users\<user>\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup\service.exe
    C:\Windows\System32\Tasks\enc.exe
    %AppData%\{GUID}\enc.exe
  5. Restart to normal mode & run offline AV/EDR scan (deploy signatures updated 2018-03-07 or newer).
  6. Audit credentials – assume all domain passwords are compromised; force reset of ALL user & service accounts.

3. File Decryption & Recovery

  • Recovery Feasibility:
    Blind written in .NET and used AES-256 + RSA-1024 hybrid; RSA public key uniquely generated per campaign. Private keys are NOT recoverable without the attacker’s help.
    – No public decryptor exists.
    – Theoretically the RSA-1024 modulus could be brute-forced (cost > $100 k in cloud compute), but no successful public crack has been published.

  • Essential Tools for Recovery instead of Decryption:
    – ShadowExplorer – Re-examine unmapped VSS copies if the delete-command was blocked (rare).
    – ReclaiMe, PhotoRec – Carve intact-but-deleted originals on unaffected drives or using forensic images.
    – Recreate keys from fully intact backup rather than pursuing decryption.

4. Other Critical Information

  • Additional Precautions / Unique Traits:
    – Blind drops a ransom note “HowDecryptFiles.hta” and sets .blind extension’s icons in HKEYCLASSESROOT, making infection obvious.
    – Deletes Windows Event Logs (often wevtutil cl Application /Security /System) to hinder forensics.
    – Overwrites original file content with 3 passes before deletion—makes raw-sector recovery difficult.
    – Message instructs payments to a BitMessage ID rather than Tor; historical addresses: BM-2cUajJ9ykza8v3ELjQkVPVVb7XkbeN7D4D.

  • Broader Impact:
    – ~1 600 known submissions to ID-Ransomware between 2017-2019.
    – US healthcare sector reported 27 breach disclosures tagged as “BLIND/Blind ransomware” to HHS OCR.
    – Credited with pioneering “big-game hunting” techniques—manual selection of high-value targets via RDP rather than indiscriminate worm spread.

Stay current: the Blind family splinter evolved into Sodinokibi/REvil months later, so remain vigilant for new file extensions or similar TTPs.

Bottom line: Prevention (lockdown RDP + immutable backups) remains the only cost-effective defense—decryption at scale is infeasible for Blind.