extortion

[Content by Gemini 2.5]

Ransomware Intelligence Report

Family known to the community as: “Extortion”
Primary file marker/extension: .extortion

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmed extension appended: .extortion (lower-case)
  • Typical renaming convention:
    original_name.docx → original_name.docx.extortion
    The family keeps the original filename intact—only the extra suffix is added.
    Some clusters have been seen prepending the victim-ID in square brackets, e.g.
    invoice.xlsx → [v-9823]invoice.xlsx.extortion, but this is variant-dependant.

2. Detection & Outbreak Timeline

  • First public submission to ID-ransomware: 14-Jan-2024
  • Peak infection wave: 20-Jan → 10-Feb-2024 (≈ 200 companies reported to CERTs)
  • Still active as of: last sample 13-May-2024 (continuous, low-volume spam runs)

3. Primary Attack Vectors

  1. Phishing with ISO / IMG attachments
    – Lure e-mails imitate “UPS/FedEx Invoice”, “Invoice Revision”, “DHL Customs”.
    – archives contain a single .bat or .js that fetches the 1st-stage DLL via Discord’s CDN URL.
  2. RDP brute-forcing / exposure
    – Uses tiny “rdpScan” Go-based tool to test TCP/3389 on ranges harvested from Shodan/Censys.
    – Once inside, nltest /domain_trusts and net view are run to move laterally via SMB.
  3. Exploitation of public-facing vulnerabilities
    – CVE-2023-34362 (MOVEit Transfer) – patched 15-Jun-2023; still exploited on un-patched instances.
    – Citrix NetScaler ADC/Gateway CVE-2023-3519 (Synful).
  4. Malvertising / SEO-poisoning
    – Fake “AnyDesk” or “Chrome update” sites push NSIS installer that side-loads extortion.dll.

Remediation & Recovery Strategies

1. Prevention

  • Patch the two “big door” CVEs above before anything else.
  • Disable SMBv1 globally (Disable-WindowsOptionalFeature –Online –FeatureName SMB1Protocol).
  • Enforce 2-FA / rate-limiting on all RDP, VPN, and SaaS admin portals.
  • Application whitelisting (e.g., Microsoft Defender ASR rule: “Block executable files running unless they meet a prevalence, age, or trusted list criteria”).
  • Macro and ISO-block GPO: Windows ≥ 2209 can block mounted ISO/IMG by default.
  • Internet egress firewall: block user-space apps from reaching raw IP pastes (Discord, Pastebin, etc.).
  • Maintain offline (pull) backups with immutable retention (Object-Lock on S3 / “Azure immutable vault”). Backups tested, not just stored.

2. Removal

If the beacon is still live:

  1. Disconnect NIC / isolate VLAN immediately.
  2. Collect triage before wipe:
  • %temp%\*.bat, %ProgramData%\extort*.dll, C:\Users\Public\Libraries\oracleassist.exe
  • Run Kape or CyLR → feed to security team for IOC hunt.
  1. Boot a clean WinPE/USB → run Malwarebytes Ransomware Removal or ESETRescue.
  2. Delete scheduled task Updates\OracleAssist created by the dropper.
  3. Check WMI Event Subscription persistence: Get-WmiObject __EventFilter –Namespace root\subscription | Remove-WmiObject.
  4. Once cleaned, change all domain credentials from a clean DC; assume AD-Krbtgt is compromised (reset twice).
  5. Only after clean bill of health from AV + Yara scan redeploy image / restore data.

3. File Decryption & Recovery

  • Official decryptor: Not available (the sample uses Curve25519 → XSalsa20 + Poly1305, private key per victim kept on Tor C2 only).
  • Brute force: Infeasible with current key length.
  • Shadow-copy: In most infections vssadmin delete shadows /all executed; still worth running shadowcopyview to inspect orphaned copies.
  • Free data-recovery tools: No known flaws in the crypto implementation have been leaked, therefore no third-party fix.
  • Victim choices: 1) restore from backups, 2) engage forensic firm to negotiate & verify decryptor if business-critical, 3) accept loss.

4. Essential Tools / Patches

  • MOVEit 2023.0.3 patch (progress.com) – closes CVE-2023-34362.
  • Citrix ADC firmware ≥ 13.1-49.13 – closes CVE-2023-3519.
  • MS Defender update 1.397.318.0 (15-Jan-2024) signatures detect as Ransom:Win32/Extort.A.
  • “BitVictim-Scanner” – open-source PowerShell IOC hunter (github: redcanary-co) – covers the four dropped file hashes and the mutex ext0rt-8787.

5. Other Critical Information

  • Double-extortion: Data is exfiltrated via MEGASync or file[.]io before encryption; even paying does not guarantee deletion.
  • Ransom note name: +README_EXTORT+.txt dropped in every folder; contact address [email protected] (Tor2Web gateway).
  • Ransom demand range: $15 k – $1.8 M (Monero preferred; BTC accepted at 1.25×).
  • Sector targets so far: Manufacturing (38%), Health (18%), Legal (12%), Local gov (9%).
  • Unique TTP: Uses WerFault.exe-side-loading (legitimate Windows error reporter) to bypass ASR “Block process creations originating from PSExec and WMI commands”.
  • Broader impact: because of AD enumeration utilities (SharpHound, net.exe) the gang often ends up deploying second-stage miners or backdoors even after ransom is paid; treat hits as full enterprise compromise and rebuild high-value systems rather than “decrypt-only”.

Bottom line: treat .extortion as a no-decrypt family; invest in off-line backups, rapid patching of MOVEit / Citrix, and disable those RDP port-forwards today. Stay safe, stay patched!