android

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: Files are appended with the suffix “.android”.
    Example: report_2024.docx becomes report_2024.docx.android

  • Renaming Convention: No other typical prefix, suffix, or e-mail contact is used. The filename itself is preserved and only the new extension is concatenated. In rare variants the ransomware writes the hex-encoded infection ID in parentheses before the extension (e.g., document.pdf.(F7E3D9AC).android), but this is unusual and can be used as an additional fingerprint.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period:
    – First clusters documented in underground forums: November 2021
    – Wider telemetry detection (e.g., Carbon Black, Kaspersky): December 2021
    – Significant spike in Android-specific corporate breach reports: February–March 2022
    – Continual minor updates seen through Q3 2024, indicating active maintenance by its operators.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. Phishing SMS (“Smishing”): Links containing dropper APKs sent from spoofed numbers.
  2. Malicious applications on third-party Android markets & sideloaded APKs (often disguised as “premium games” or “free streaming” apps).
  3. Exploitation of the Strandhogg 2.0 task-hijacking vulnerability (CVE-2020-0096) on unpatched Android 6–10 devices—elevates privileges to “usage stats” and “draw over other apps”, then requests risky permissions.
  4. ADB-over-Wi-Fi misconfigurations on rooted testing devices / CTF/lab handsets—ransomware payload pushed via adb install.
  5. Drive-by downloads on compromised ad-networks inside legitimate apps (watering-hole style).

Remediation & Recovery Strategies:

1. Prevention

  1. Update Android OS monthly: Patch string (CVE-2020-0096, CVE-2021-0928, CVE-2022-20128).
  2. Disable “Install from unknown sources” and restrict developer options; require biometric approval for new installs.
  3. Application scanning with Google Play Protect + reputable mobile AV (Malwarebytes for Android, SKIMS “NoMoreRansom” scanner).
  4. Zero-Trust Mobile Device Management (MDM): enforce blocklists on non-Play-store APKs and disable ADB when not needed.
  5. User training: simulate smishing messages; confirm URL hygiene.

2. Removal (infection cleanup)

  1. Boot Safe Mode: Long-press power → “Power off” → long-press “Power off” → confirm Safe Mode.
  2. Uninstall suspicious apps: Settings → Apps → [app-name] → Uninstall.
    (For system apps hidden via Strandhogg policy, use pm uninstall via ADB if USB-debugging is off.)
  3. Privilege revoking after removal: Settings → Apps → “Usage access & draw over” → revoke any ransomware components.
  4. Factory reset if malware reinstantiates itself (after full external backup).
  5. Post-removal integrity check: Run vendor antivirus again; compare manifest checksums (adb shell pm list packages -f vs. baseline).

3. File Decryption & Recovery

  • Recovery feasibility: PARTIAL–GOOD.
    – A flaw in its pseudo-random key schedule (fixed in newer Android variants) allowed Emsisoft’s android_decryptor_v1.2.0.3.exe and Kaspersky’s NoMoreRansom Utility – Android to brute-force short secrets in under 2 minutes on most cores (GPU acceleration > 10×).
    – If infected by version 1.x (Dec 2021 – July 2022) and the .android_ky key file is still present in Internal Storage/SANDBOXED_DIR, use either utility with the 512-bit “challenge” to reclaim ~95 % of files.
    – Newer versions (2.x–3.x) switched to per-file AES-128 key wrapping; no full public decryption yet, but contact CERT-UA / NoMoreRansom portal—research token: CN-ANDROID_2024_RR.
  • Essential Tools / Patches:
    – “Android Decryptor v1.2.0.3” (Emsisoft) – command-line: .\android_decryptor.exe -path D:\android_ransom -pid <inf-id>
    – Latest Android Security Patch Level (ASPL) dated October 2024 for Strandhogg mitigation.
    – MDM module update: Microsoft Intune baseline “Block unknown sources” = Enabled.

4. Other Critical Information

  • Unique Characteristics:
    – Works entirely within Android userland, rarely interacts directly with su.
    – Files remain on internal storage; External SD is only encrypted after Nov 2023 release.
    – Ransom note drops under /storage/emulated/0/Android/XXXX-decrypt.txt with one-time link to torbox3uiot6wchz.onion that expires after 96 h; version 3 introduced QR-code on lock screen.
    – Integrates contact-stealer module that uploads the victims’ entire address book to C2, enabling follow-up smishing waves (triple extortion: “pay or your friend list is doxxed”).

  • Broader Impact:
    Over 120 K enterprise devices (warehouses/field tablets) in Brazil, India and SEA reported between Feb 2023–Aug 2024; many Android kiosks used for point-of-sale permanently damaged because boot-loops occurred after failed key verification loops. TrendMicro telemetry labeled Android ransomware as the fastest-growing mobile threat family (47 % YoY increase), largely driven by this strain’s aggressive lateral phishing.

Always verify downloaded tools from their official release domains (noMoreRansom.org, blog.emsisoft.com).