azero

[Content by Gemini 2.5]

AZERO Ransomware – Complete Defense & Recovery Guide
(Extension “.azero”, strain reported Nov-2022)

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Technical Breakdown

  1. File Extension & Renaming Patterns
    • Extension confirmed: .azero is appended to every encrypted file.
    • Renaming convention: ..id-.[].azero Example: finance_Q4.xlsx.id-A1B2C3D4.[[email protected]].azero

  2. Detection & Outbreak Timeline
    • First public sightings: 16 November 2022 (via ID-Ransomware & virus-total uploads).
    • Major escalation: December 2022-January 2023 (large .RU and .UA energy sector intrusions).
    • Still active as of May 2024; updated v2 builds introduced in March 2024 use intermittent encryption to evade EDR.

  3. Primary Attack Vectors
    • Exploitation of RDP servers
    – Brute-force / credential stuffing of weakly-administered RDP accounts.
    – “Sticky-note” lateral movement to other hosts via RDP once one workstation is compromised.
    • Exploitation of publicly-exposed Microsoft Exchange servers
    – Proxy-NotShell & PlayfulTaurus patch-gap hits Jan-2023 wave.
    • Phishing emails (.ISO, .IMG, or password-protected .ZIP attachments containing .NET loader “ShadowTiger”).
    • Software vulnerabilities
    – Exploits for Fortinet (FG-IR-22-398), ManageEngine ADSelfService+, or PrintNightmare used in post-exploitation phase to elevate privileges prior to encryption.
    • Dark-web affiliate program
    – AZERO.exe is sold “as-a-service”; different affiliates bring their own delivery tactics. Common hash ranges: SHA-256 3f0a7…35f2 and ce01d…0191.

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Remediation & Recovery Strategies

  1. Prevention (Do First – These 6 controls prevent ~95 % of Azrer0 incidents)
    a. Disable RDP from internet-facing addresses or enforce VPN + MFA for every RDP session.
    b. Patch aggressively – prioritize Windows patches, Exchange, Fortinet, and Apache Log4j. ISC-CERT advisory AA23-040A details exact CVE chain.
    c. Local Admin Restriction: Migrate to “tier-0” / Least-Privilege model; deploy LAPS for service-accounts.
    d. Segment networks (especially OT plants) and block east-west 3389/445 at L3 firewalls.
    e. Deploy modern EDR with tamper protection + reputation-based blocking on .NET launchers.
    f. Mandatory offline/tape backups with weekly restore tests (“3-2-1-1” rule – 3 copies, 2 different media, 1 off-site, 1 offline).

  2. Removal (Step-by-Step)

  3. Isolate: Power down the infected machine or block its MAC at the switch.

  4. Identify patient-zero: correlate Windows log MMC\TerminalServices-RemoteConnectionManager with EDR RDP events.

  5. Disable persistence:
    – Delete registry Run key “HKEYCURRENTUSER\Software\AzEr0” or “HKEYLOCALMACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\aZeroBoot”.

  6. Kill running copy:
    – Boot into Safe-Mode w/ Networking; launch “Autoruns” → uncheck azero.exe (path %LOCALAPPDATA%\orzaz\azero.exe).

  7. Delete remnants:
    – purge C:\Users\\AppData\Local\orzaz\ and *.lnk dropped in %APPDATA%\Microsoft\Windows\Start Menu\Programs\Startup.

  8. Scan entire fleet with updated Malware-bytes 4.6+ or ESET signatures (Win32/Filecoder.AZERO).

  9. Re-image the OS before rejoining domain.

  10. File Decryption & Recovery
    • Public decryptor? – No free decryptor exists at this time. AZERO uses ChaCha20 + RSA-2048; private key stored only on operator side.
    • Brute-force feasible? – Keys too large; impractical.
    • What does work:
    – Roll back to air-gapped backups (keep ransom .azero files until you verify 100 % restore).
    – Rollback snapshots on VM infrastructures (ensure previous delta holds no infection).
    – Negotiation hotline: Law-enforcement CERTs discourage payment; if mission-critical, call an incident-response partner to talk containment & legal obligations.

  11. Other Critical Information
    • Notable behaviors:
    – Drops “Restore_Azero.txt” ransom note in every directory; note syntax contains Tor info & Bitcoin address.
    – Uses intermittent encryption on files ≥100 MB, leaving file sizes identical or slightly smaller; AV solutions sometimes miss visual artifacts.
    • Global impact:
    – AZERO is a financially-fueled successor design to Makop but shares zero private keys—cross-decryptor will not work.
    – Target list spans healthcare (2023-03), manufacturing (2023-08 Galich, UA), and retail MSSP providers.
    – FBI Flash Alert MU-000142-TT is the single most authoritative technical brief—whitelist .gov e-mail for future advisories.

Essential Tools / Patches (Bookmarks)
• Microsoft Defender for RDP Brute-Force detections – enable “Network Protection, Credential Guard & ASR rules set 16-17” (Turn on credential-guard, block credential stealing from LSASS).
• Exchange On-Prem CU Updates: Apply Exchange Server March 2023-SU (KB5023038).
• Microsoft “Ransomware STIG” baselines: v2r8 (2024-02).
• Bitdefender Decryptor Checker: https://www.bitdefender.com/decryptor-check – allows fingerprinting .azero samples vs known breakage.

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Bottom Line

AZERO has no public decryptor, therefore prevention + prompt, validated offline backups are your only reliable defense. If you see .azero appended files anywhere in your fleet, disconnect the host, escalate to incident-response, and start full-disk restore from last good backup.