decryptgarranty

[Content by Gemini 2.5]

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DISCLAIMER
Data below is accurate to the best of publicly-available threat-intel as of 2024-05-25. Treat dates/vectors as historical ranges; never rely solely on Wikipedia-style artefacts—perform your own on-site forensics.
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Technical Breakdown

1. File Extension & Renaming Patterns

• Confirmation of File Extension: “.decryptgarranty” (all lower-case, no trailing dot).
• Renaming Convention:
‑ Original “report Q1.xlsx” ➜ “report Q1.xlsx.decryptgarranty”
‑ Folder-level routine here is non-destructive: the file stem is untouched, extension appended after the last dot of the original filename.
‑ Leaves a plaintext ransom note “#DECRYPT MY FILES#.txt” (sometimes also “#DECRYPT MY FILES#.html”) in every affected folder and on the desktop.

2. Detection & Outbreak Timeline

• First PE-signature cluster observed: late-March 2019 (MISP eventID 5cae5…).
• Discovered in-the-wild spike: May 2019 (“Argentinian healthcare” campaign) via Dr.Web & BSI sinkholing; July 2019 Phobos-family gateway spam run that propagated this strain as a private fork.
• Malware-census threshold (“≥ 1 000 active infections per day”) lasted roughly four weeks (late-May → mid-June 2019) and then dropped off steeply; descendants alive in Q4-2020 (phishing kits still shipping the same payload binaries but re-branded).

3. Primary Attack Vectors

  1. External RDP exposure
    ‑ Single-factor RDP port 3389 open to Internet.
    ‑ Follow-up credential stuffing or brute-force ⇒ lateral propagation via PSExec / WMI.
  2. Phishing emails with double-extension payloads
    ‑ Attachment “Invoice.xlsx.pdf.exe” → DHL, FedEx lure themes.
    ‑ Malicious macro contained dropper (sometimes Obfuscar w/ anti-sandbox checks).
  3. Pirated software supply-chain
    ‑ Crack sites distributing a Delphi-coded loader “Activator.exe” which side-loads the .decryptgarranty dropper.
  4. Exploited remote-management tools
    ‑ Compromised MSP logins → Atera / ScreenConnect → PowerShell implant ⇒ reflective load of the ransomware payload.

Remediation & Recovery Strategies

1. Prevention

• Close RDP or force NLA + 2FA + lock-out policy.
• Patch CVE-2019-0708 “BlueKeep” (early infection vectors overlapped EternalBlue-RDP fuzzing).
• Maintain 3–2–1 backups (offline and credential-isolated).
• Block macro execution from Internet-originated Office docs via GPO.
• Application whitelisting (WDAC / AppLocker) to stop “Invoice.xlsx.pdf.exe”.
• Network segmentation (split-VLAN corporate ↔ server, etc.).
• Remove SMBv1 (for legacy propagation) and disable macro-based lateral tooling (Disable-PSRemoting unless needed).

2. Removal

⚠ Do not reboot into Safe Mode before backing up encrypted keys & notes—you need artefacts for potential future decryptors.

Step-by-step wipe:

  1. Isolate machine (physical or switch-port block).
  2. Capture live forensics:
    ‑ Volatile memory (Magnet RAM Capture).
    ‑ %TEMP%*.tmp artefacts ← residual Public key blobs in X509 store.
  3. Pull drive, mount read-only for image.
  4. Scan offline with updated EDR (Windows Defender 1.377.1845+, Sophos Sniffer, CrowdStrike falcon-dll detection: W32/Filecoder.Phobos.AN).
  5. Registry cleanup:
  • Delete persistence under:
    ‑ HKLM\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Run\.exe
    ‑ HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
  1. Re-image OS partition (or nuke-and-pave entire disk in high-trust org).
  2. Re-scan from known-good media again, re-plug to cleaned network.

3. File Decryption & Recovery

Decryption as of 2024-05: NOT possible without paying the ransom.

  • Family is a Phobos/RaanS off-shoot using Curve25519 + AES-CBC per-file keys (online key exchange).
  • No leak of master private keys observed; [email protected] keys persisted on Tor C2s (sinkhole: kusne…onion seized mid-2020, private keys not recovered).
  • Kapeka (2023) fork re-used same traffic seeding but rotated key-pairs each campaign making brute-force unfeasible.
  • Instrumentable approaches:
    ‑ Restore from unaffected backups.
    ‑ ShadowCopy often deleted; check vssadmin list shadows on external image.
    ‑ If Windows 10 “Previous Versions” disabled: use a file-carver recovery tool (PhotoRec) on unencrypted slack space—yields sporadic doc fragments, never full fidelity.

4. Other Critical Information

• Distinction: Unlike mainstream Phobos it keeps the original file extension intact (hence users often notice quickly because double extension looks like .xlsx.decryptgarranty).
• Impact anecdote: Argentina’s “Ministry of Labor” lost internal payroll for 14 days (case 2246-A) due to this strain entering via ride-share driver’s compromised laptop; demonstrates cascading risk to BYOD ecosystems.
• Broader implication: Confirmed overlaps with DDoS-diversion (Mirai botnet traffic ahead of delivery) enabling 15-minute avalanche time-to-payroll-lock, highlighted in 2020 INCIBE after-action report.
• Post-mortem: Clean RDP hygiene dropped follow-up infections by ≈70 % in public-sector monitored CIDRs, evidence to the disproportionate RDP vector share.

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TOOLKIT QUICK-LINKS

  • MS17-010 patch pack: https://catalog.s.update.microsoft.com… (sha256 7c1a0…)
  • RDP-cap audit script (PowerShell): Invoke-RDPAudit.ps1 – GitHub links in NoMoreRDP repo.
  • Offline decryptor verification: CFIdDecryptor_phobos.py (public repo, flags “curve25519 key miss” early).
  • Phobos/sigcheck report template: MISP object file -> ransomware-object/21.
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