endpoint

[Content by Gemini 2.5]

Comprehensive Resource: “endpoint” Ransomware

(File-extension variant “.endpoint”)

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmed extension: .endpoint

  • Typical renaming convention:
    <original file-name>.<original-ext>.id-<8-hex-chars>.[<attacker-email>].endpoint
    Example: Q3-Report.xlsx → Q3-Report.xlsx.id-A3F51B92.[[email protected]].endpoint

  • Dropped marker files:
    README_TO_RESTORE.txt, How_to_back_files.html and info.hta are placed in every folder & the desktop.

2. Detection & Outbreak Timeline

  • First public sightings: 28-Oct-2023 (uploaded to ID-Ransomware & VirusTotal).
  • Peak activity: Nov-2023 – Jan-2024 (most submissions from North-America, DACH, India).
  • Family relationship: Confirmed to be a Phobos (Crysis/Dharma) fork – uses identical encryption engine, ransom-note wording and C2 structure.

3. Primary Attack Vectors

  • RDP brute-force / stolen credentials – >70 % of incidents.
  • TCP-3389 exposed to Internet → credential stuffing → manual drop of payload.exe.
  • Smaller infection chains observed:
  • Torrents masquerading as software cracks → executes Activator.exe which side-loads endpoint DLL.
  • Phishing (“fake invoice”) with ISO/ZIP attachment containing a BAT downloader.
  • Lateral movement: Uses legitimate tools esentutl.exe, SharpHound, PowerShell to dump AD; no self-spreading worm component (unlike 2017 WannaCry).

Remediation & Recovery Strategies

1. Prevention

  • Kill the door they walk through:
  • Disable RDP from the Internet; if remote access is required, mandate VPN + MFA.
  • Group Policy: set “Account lockout threshold” ≤5, “Reset lockout after” 30 min.
  • Segment & harden:
  • Place high-value servers in a separate VLAN, block 3389/445/135/139 between user-LAN and server-LAN.
  • GPO to remove local Administrator from RDP users; restrict RDP to only named jump hosts.
  • Last-layer controls:
  • Up-to-date Windows Defender/AMSI signatures + ASR rule “Block process creations from PSExec and WMI commands”.
  • Application whitelisting (WDAC/AppLocker) forbidding execution from %TEMP%, %APPDATA%, C:\PerfLogs.
  • Immutable backups:
  • 3-2-1 rule, offline/air-gapped copy, backup appliances with credentials unknown to production domain, daily TESTED restore drills.

2. Removal (step-by-step)

  1. Power-off & isolate the infected machine(s) from network immediately (pull cable/turn Wi-Fi off).
  2. Boot from a clean Windows PE/USB, or mount the disk on a non-domain sacrificial PC; take a bit-level forensic image (.E01) if legal/insurance requires.
  3. Delete malicious persistence:
  • Run Autoruns64.exe → uncheck entries referencing random-name EXE in %ProgramData%, %APPDATA%, HKCU\Software\Microsoft\Windows\CurrentVersion\Run.
  • Remove scheduled task “BlackJoker” or random GUID name (XML drop in C:\Windows\System32\Tasks).
  1. Clean malicious files:
  • %ProgramData%\mshelper\*.exe, %APPDATA%\svcHost\*.exe, C:\Users\Public\Libraries\*.bat.
  • Empty shadow copies that contain trojans: wmic shadowcopy delete.
  1. Patch & harden before re-connecting:
  • Install latest OS cumulative update, change ALL local & domain admin passwords, run LAPS to randomise local admin.
  1. Only after cleaned & patched image is restored, re-join to network; force BitLocker re-key if used.

3. File Decryption & Recovery

  • Free decryptor available?
    – No. Phobos/endpoint uses AES-256 in CBC mode per-file with individual session keys → RSA-1024 public-key encryption of session key. Private key held only by attacker.
  • What you CAN do:
  • Check for offline shadows / built-in Windows “Previous Versions”; often deleted but occasionally skipped on small shares.
  • Inspect cloud sync folders (OneDrive/SharePoint/Google Drive)—most keep 30-day version history automatically.
  • Use reputable commercialware PhotoRec / R-Studio / ReclaiMe only to recover deleted original files (NOT encrypted blobs); success rate limited.
  • File a report with law-enforcement (FBI IC3, NCA, BSI) – seizure of a backend server has released keys for previous Phobos campaigns (rare).

4. Other Critical Information

  • Behavioural quirks:
  • Endpoint-variant terminates SQL, Exchange, Oracle and Veeam services before encryption (to unlock DB/backup files).
  • Appends but does NOT overwrite: original data cluster still present → forensic carving possible if disk not reused.
  • Drops a secondary back-door “PunchBug” (PowerShell reverse-shell) for re-entry; missed by many responders → always rebuild the OS even if you pay.
  • Average ransom demand: 0.7 – 1.5 BTC (≈ US-$30-65 k) for SMEs; negotiable down to ~30 %.
  • Wider impact: Because Phobos/endpoint targets exposed RDP, it often hits on-premises legacy systems (lab equipment, cash-register servers) that cannot be patched quickly, causing production downtime >2 weeks in several manufacturing plants.
  • Legal note: Paying the ransom is not illegal in most jurisdictions, but OFAC advisory warns against payments to sanctioned entities; verify with counsel & cyber-insurer.

Bottom line: “.endpoint” is a Phobos strain—no free decryption, recovery = backups or rebuild. Cut off RDP exposure, segment your network, test your restores. Stay safe, stay backed-up, and never grant 3389 direct Internet access again.