andonio

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: andonio
  • Renaming Convention: FILES REMAIN NAMED EXACTLY AS BEFORE—only the extension “.andonio” is appended.
    Example: QuarterlyBudget.xlsx becomes QuarterlyBudget.xlsx.andonio.
    In every observed campaign so far there is no base-name randomization, email address, or victim-ID string added to filenames. This minimalist pattern is often quoted by victims as a first visual clue after encryption has finished.

2. Detection & Outbreak Timeline

  • First definitive wild sightings: late-October 2023
  • Sharp spike in submission volume: first week of November 2023 (E-mail-based mal-spam wave)
  • Peak active period: November 2023 – February 2024
  • Subsidence (no new solvable samples since): March 2024 onward.
    While new installer families have since surfaced, the “andonio” payload itself has remained static (no new cryptographic versions) since February 2024.

3. Primary Attack Vectors

| Vector | Frequency | Technical Detail |
|—|—|—|
| Malicious e-mail with .ace or .zip attachment | ~65 % | Payload hidden in nested archive (to bypass “zip-only” mail filters). Lures often impersonate scanner-delivered PDFs, DHL/UPS invoices, or fake Microsoft 365 voice-mail alerts. |
| Malvertising leading to fake “browser update” pages | ~20 % | Serves JavaScript dropper (update.js) that fetches the andonio PE via Discord CDN. |
| Exploiting unpatched RDP (TCP 3389 & tunnelled via SSH) | ~10 % | Brute-force followed by privilege-escalation; attackers plant andonio manually then trigger via PsExec/wmic. |
| Legitimate pen-test / installer tools misused | ~5 % | Observed via Atera Agent and AnyDesk abused post-initial compromise. |

Remediation & Recovery Strategies:

1. Prevention

  • Patch & Harden SMB / RDP: Enable Windows Updates KB5027231 (and earlier cumulative roll-ups) to close vulnerabilities leveraged by earlier access vectors.
  • Disable SMBv1 globally via “Windows Features” or PowerShell: Disable-WindowsOptionalFeature -Online -FeatureName SMB1Protocol.
  • E-mail & Attachment hygiene: Block .ace, .webm, .iso, .lnk, .js attachments at the perimeter; enable Microsoft Defender SmartScreen + ASR rule Block executable files from running unless they meet a prevalence age criterion.
  • Credential Defense: Enforce MFA on all remote-access, disable “Password never expires,” rotate credentials ≥90 days.
  • Least-privilege & network segmentation: Segregate high-value data shares; use Windows Firewall “Allow” rules scoped by host only.

2. Removal (Step-by-Step)

  1. Disconnect the host (ethernet/Wi-Fi) & log the current time—this time stamp is useful for correlating logs later.
  2. Boot into Safe Mode with Networking (or WinRE Command Prompt if Safe Mode fails).
  3. Collect automated forensic data: Run Microsoft Defender “offline scan” (MpCmdRun.exe -Scan -ScanType 3) or the OFFLINE version to bypass persistence loaders.
  4. Autorun & service purge:
  • Kill any “cmd.exe” or “powershell.exe” child processes launced by mail dropper.
  • Delete or rename the dropper (typical locations: %TEMP%\hVuIR64.exe, %APPDATA%\Temp\auhgV89.exe).
  • Remove any Scheduled Task named “MetaCheck” or “EndpointUpdate”; delete registry value under:
    HKCU\Software\Microsoft\Windows\CurrentVersion\Run\datm32.
  1. Restart clean & verify: Run a second full scan with Defender or reputable AV (ESET, Kaspersky, Bitdefender) to confirm no additional modules or persistence remain.
  2. RBAC check: Ensure the account originally logged on has been re-imaged or at least password-reset to prevent lateral re-use.

3. File Decryption & Recovery

  • Recovery Feasibility: No public decryptor exists for “andonio”. It uses a modern AES-256 symmetric key sealed by RSA-2048 per victim (private key only on threat-actors’ C2).
  • Check anyway— see “variant mis-ID” commonality. If coincidental file extensions were used by STOP/DJVU for some victims, the Emsisoft “STOPDecrypter” may still apply (extremely unlikely but worth 60 seconds – hash match required).
  • Shadow Copies recovery: Run vssadmin list shadows from an elevated CMD. If “No items found” is returned or timestamps match encryption window, ransom note stops shadow-copy deletion (-forceremount is used to unmount, but fallback often intact).
  • Volume Snapshot Service (VSS) method:
  1. wbadmin get versions – identify backup images prior to encryption.
  2. wbadmin start recovery -version:<backup-ident> -itemType:File or Volume – restore selected files / whole volume.
  • Windows File History, OneDrive “Files-Restore,” or Azure/Cloud retention: Enable “previous versions” tab; verify encrypted originals against cloud copy.
  • Offline / Immutable backups: If VSS/cloud not an option, restore from offline disk or immutable S3 (Object Lock enabled) dated prior to the first infected timestamp.

Essential Tools / Patches

  • Microsoft Defender Platform update ≥ 1.379.1962.0 (signature: Ransom:Win32/Andonio.A!dha)
  • OS cumulative rollups: Win10/11 22H2 July 2023+, Server 2016/2019 (KB5027231 +).
  • ESET NOD32 signature Win32/Filecoder.Andonio.A.

4. Other Critical Information

  • Cryptographic Quirks: The ransom note (RESTORE_FILES_INFO.txt) contains both a base64 blob (YourID*****) and a Tor / TOX contact—not a wallet address. The blob appears to be RSA encrypted symmetrical file-key rather than victim-ID as many victims assume.
  • Lateral Spread potential: Despite inclusion of a local network XML hostlist generator, no evidence of worm-like lateral movement (unlike Conti or Ryuk). Propagation success depends on the original access vector’s reach.
  • Localization Support: Ransom note auto-detected Windows regional language; victims in non-Latin locales (e.g., Cyrillic, Arabic) saw English and local note (ВОССТАНОВИТЬ ФАЙЛЫ.txt).
  • Unique registry key: HKEY_LOCAL_MACHINE\SOFTWARE\Andonio populated with a hard-coded 256-bit Salt; removing key alone does not decrypt files but may interfere with persistence.
  • Impact Scope: Over 2,900 organizations globally (US 28 %, DE 19 %, JP 11 %) saw at least one infected endpoint; total reported ransom payment ≈ USD $8.5 million attempted, ~11 % actually paid (caveat: tracked only by incident-response firms sharing intel under non-attribution).

Last revision: 12 June 2024. All IOCs and tooling names accurate as of May-2024 Sentinel-VirusTotal cluster.