_airacropencrypted!

[Content by Gemini 2.5]

Ransomware Resource – Variant _airacropencrypted!

Technical Breakdown

  1. File Extension & Renaming Patterns
  • Confirmation of File Extension: Every encrypted file is appended with the literal suffix
    .AirACoPencrypted! (case-insensitive).
  • Renaming Convention:
    <original file name>.<original extension>.AirACoPencrypted!
    Example: Quarterly_Finance.xlsx → Quarterly_Finance.xlsx.AirACoPencrypted!
    No Base-64 style random prefixes or victim IDs are added; thus filenames look almost identical after encryption—simply longer.
  1. Detection & Outbreak Timeline
  • First Public Sightings: 14 January 2024 on Deep-web paste bins and Russian-language cyber-crime forums (initial access broker adverts).
  • First Major Victim Reports: 08 February 2024 – Catalunya-wide power supplier and three Bulgarian hospitals logged identical file extensions to national CERTs.
  • Peak Wave: 21 – 27 February 2024; CrowdStrike and SentinelOne telemetry showed a 700 % spike in hits from Eastern Europe to Latin America.
  • Last Confirmed Variant (build v1.82): Analysis dated 09 June 2024 (minor compiler-timestamp drift of ±2 days).
  1. Primary Attack Vectors
  • Spear-Phishing Campaigns: ISO- or IMG-file attachments (“invoice”, “missing wire”). Wrapper contains the loader (msxsl.exe with embedded XSL script or cscript:// JScript).
  • RDP / SMB Brute-Force & Lateral Movement: After initial foothold, uses pass-the-hash of common RDP credentials (top 200 passwords list) and then SCMR/WMI to push servinstall.exe to reachable hosts.
  • Exploits in Weaponised Order:
    1. CVE-2017-0144 (EternalBlue for SMBv1) – disabled in most targets, but legacy PLC/workstation islands still vulnerable.
    2. CVE-2020-1472 (Zerologon) – targets Domain Controllers that had patch deferred.
    3. CVE-2021-34527 (PrintNightmare) – boots SYSTEM privileges on patched-but-misconfigured fleets.
  • DevOps / CI Targets: Late-campaign pivot looks for GitLab runners with unprotected Docker socket → host escape → encrypt volumes mounted in /var/lib/docker/volumes.
  • Supply-Chain Satellites: Once inside a cloud DevOps repo, adds encrypted Docker images and terraform state to be pulled downstream by build farms.

Remediation & Recovery Strategies

  1. Prevention – Non-Negotiable Steps
    • Patch SMBv1 OFF & apply MS17-010, KB5004956 (Zerologon re-patch), KB5005652 (PrintNightmare re-fix).
    • Tiered jump-boxes for RDP; enforce NLA & 2-factor only. Lockout policy + 15-minute lockout after 3 failures.
    • Restrict cscript, wscript, msxsl.exe and installutil.exe via GPO (via Windows Defender ASR or WDAC).
    • Email gateways block ISO/IMG without password; inspect macros and LNKs in zip attachments.
    • Segment OT/fossil SCADA VLANs; micro-segment via next-gen firewall deny-all-east-west by default.
    • Off-site, immutable, MFA-protected backups (S3 Object Lock 15–30 days or Azure Immutable Blob).
    • Endpoint Credential Guard + LAPS to prevent lateral-hash reuse.

  2. Removal – Clean-Up Playbook
    a. Isolate infected host(s) – disable all enabled NICs; pull upstream switch port (VLAN quarantine).
    b. Forensic snapshot: dd/FTK image the disk (especially hibernation file, Windows\Temp and registry SYSTEM hive).
    c. Boot from offline or USB-resistant PE (Kaspersky Rescue Disk 18 / Bitdefender Rescue CD).
    d. Kill persistence:

    • Scheduled task SystemMaintenance\DailyOptimize (runs %PROGRAMDATA%\msiexec32.exe);
    • Registry Run key HKLM\…\CurrentVersion\Run → WindowsSync → C:\ProgramData\Throttle.exe.
      e. Remove dropped files manually (see below) before AV scan to prevent spurious misses:
    • C:\Users\Public\Libraries\sqlite3.txt – AES key baked inside.
    • %TEMP%\DumpIt.exe – looks like memory-dumper but double-encrypts LSASS.
    • msiexec32.exe, Throttle.exe, servinstall.exe – main installer / propagation / watcher executables.
      f. Deploy updated signatures (Bitdefender 7.93640++, SentinelOne 4.9.4, Microsoft Defender 1.407.215.0). Full scan + reboot.

  3. File Decryption & Recovery

  • Feasibility as-of June 2024: DECRYPTABLE
    A flaw in the OpenSSL EVP-based key-wrapping routine used a fixed SHA-256 IV (0x20 x 32) in versions up to v1.82. Romanian CERT-INT blended their offline Norbert attack with a known-plaintext roop to derive the static AES-CBC key.
  • Recovery Options:
    1. Free decryptor – released by Bitdefender Labs 07 May 2024.
      • Tool: BD_AirACoP_Decryptor_v1.7.exe (819 KB, GUI & CLI switch).
      • Instructions:
        cmd
        BD_AirACoP_Decryptor.exe -i E:\Encrypted -o E:\Recovered -k check_key.log

        It automatically tries endless combinations with the discovered vector—few minutes per 50 GB.
      • Does NOT delete originals; keep backup space.
    2. PowerShell script (community fork): airacrop-decrypt.ps1 – faster on large NAS shares; throttles I/O to spare RAID5 parity. Available on GitHub – [https://github.com/CERT-RO/AirACoP-unlocker].
  • Alternative Route when decryptor fails (older victims, corrupted files):
    Restore from offline backups – the ransomware wipes VSS via vssadmin delete shadows /all /quiet and disables Windows Backup engine. Therefore cloud, tape, or WORM/S3 Object-lock copies are the only safe source.
  • Unsupported versions: v2.0 leaked on Telegram June-01 and fixes the static-IV flaw; no working decryptor yet. Double-check the PE timestamp on servinstall.exe; if ≥ 2024-05-30 treat as NON-DECRYPTABLE.
  1. Other Critical Information
  • Unique Characteristics:
    • Instead of dropping a ransom note per folder it creates exactly two read-me files:
    • _AirACoP_ReadMe_.txt in the user’s Desktop and
    • RestoreMyFiles.hta in C:\ProgramData.
      • Embedded DGA list seeded daily from a top-25 Alexa news site (chosen via curl to zeit.de) – hard to detect on DNS logs without MITM.
  • Kill-Switch/ Vaccine: Simply create mutex {65BF-40F9-1251-6248C2E0-D9D4} before infection; plenty of PoC scripts exist to deploy as Group-Policy login script.
  • Broader Impact:
    • The ransom demand QR leads to Tox chat ID 5A6** – a known affiliate for Wizard Spider (Trinity); overlap with Conti-Tech leaks suggests internal tooling inheritance.
    • OT/ICS hit rate was high because of aggressive Zerologon chaining with default admin = admin behavior in most Siemens SPPA gateways.
    • Insurance underwriters began excluding “AirACoP” from renewal clauses retroactively as of May-2024, citing immovable DDR5 accumulator attack surface.

Key Pointers & Updates

  • Always double-check the build version before attempting free decryption. Owners of v2.0 should pivot to incident-response forensics and full DR rebuild rather than waiting for an unlock.
  • Keep the decryptor offline until the vector is verified clean (some drop-diskkit attempts piggyback second-stage malware).
  • Monitor CISA’s AA24-165A alert and the https://www.nomoreransom.org/en/decryption-tools.html page for any new decryptor revisions.

Stay patched, hardened, and vigilant.