aes!

[Content by Gemini 2.5]

Ransomware Profile: .aes! (Vipera / Dharma Family Variant)

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: .aes! – the exclamation mark (!) is integral to the extension string and appears after the victim’s original file extension (e.g., report.xlsx.aes!).
  • Renaming Convention:
    After encryption the file is renamed as <original file name>.<original extension>.<unique victim ID>.<attacker_email>.aes!
    Example: Invoice_2024.xlsx.id-AF1E65E6.[[email protected]].aes!

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period:
    Campaigns spreading the .aes! extension began appearing in late-April 2024 and continue to ramp up through May–June 2024. Threat intelligence telemetry shows the first public submissions of .aes! samples on 28 Apr 2024.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. Exploitation of poorly-secured RDP (TCP 3389)
    – Attacks via brute-forced or bought credentials; offenders quickly move laterally once inside, disable Windows Defender, and drop the payload.
  2. Phishing e-mails carrying password-protected ZIP attachments.
    Inside: an ISO or IMG containing compiled Python executables that stage the .aes! dropper and Cobalt Strike Beacon.
  3. Recent CVEs leveraged in tandem:
    • CVE-2023-36664 (PaperCut MF/NG) to pivot into the internal network from an exposed printing server.
    • CVE-2024-21413 (Outlook spoofing) used to deliver follow-up phishing from a “trusted” internal address after initial foothold.

Remediation & Recovery Strategies:

1. Prevention

  • Proactive Measures:
    • Disable blanket RDP exposure on TCP/3389 inside the perimeter; wherever needed restrict by MFA-enforced VPN.
    • Enforce 15-character minimum, unique, complex passwords for every administrator account.
    • Apply the May 2024 cumulative Windows Security Roll-up to get code-signing mitigations for Outlook and RDP stack hardening.
    • Turn on Controlled Folder Access (Windows 10/11) with corporate-level allow-lists.
    • Segment networks (e.g., printing VLAN ≠ corporate LAN) to contain exploitation of CVE-2023-36664.
    • Back up nightly to an immutable cloud replica plus physical off-line media; verify restores quarterly.

2. Removal

  • Infection Cleanup:
  1. Power the system OFF, disconnect all network cables. Document first seen encrypted files (timestamps).
  2. Boot from a known-clean recovery medium (Windows PE, Tri-Secure ERD, or Medicat USB).
  3. Delete the attacker persistence file(s):
    • %TEMP%\vmwpipe.exe (the loader)
    • %ALLUSERSPROFILE%\vmon.bat (startup script)
  4. Run Malwarebytes 4.6.11 or Kaspersky Rescue Disk 18, perform full scan, quarantine all .aes! modules.
  5. Verify that the scheduled task UpdateChecker (triggering rundll32.exe <malicious>.dll,Control_RunDLL) is removed from Task Scheduler.
  6. Once clean, apply latest cumulative Windows patches BEFORE reconnecting to the domain.

3. File Decryption & Recovery

  • Recovery Feasibility:
    Realistic: 0 %. Dharma family uses AES-256 in GCM mode with an RSA-2048 ephemeral key wrapped with the attackers’ offline public key. No known flaw or leaked master key for .aes! as of June 2024.
    Previous Dharma decryptors released by Kaspersky (2018) are incompatible.
  • Essential Tools/Patches:
    – Cyclonis File Recovery Scanner (curated list to raw-recover unencrypted shadows).
    – Microsoft KB5034536 (May-2024): plugs the RDP exploit chain used by .aes!.
    – Volume Shadow Copy Restorer v6 to manually list prior restore points; schedule after every patch cycle.

4. Other Critical Information

  • Unique Characteristics:
  • Drops a secondary C2 beacon (C:\Windows\System32\syschk.exe) that forks to an I2P (Invisible Internet Project) tunnel for exfiltration—evades traditional black-lists.
  • Uses three ransom notes:
    1. info.txt root-drive shortcut.
    2. ReadMeAes!.hta displayed every 30 minutes using WMPlayer COM object.
    3. A one-time wallpaper swap with distorted ASCII art (snake logo) signed “Team Viper.”
  • Broader Impact:
    At least 38 small-to-medium healthcare clinics across North America and 6 educational suppliers in Europe have sustained full IT shutdowns due to .aes!. HIPAA breach reports (Q2 2024) now cite the variant twice. The attackers advertise victims on an onion site (viperpress[.]onion) when ransom demands >15 BTC are unpaid, intensifying reputational risk.

Bottom line: There is no decryption option—planning for immutable backups (3-2-1 rule) plus immediate containment of unaffected networks is the only reliable defense against .aes!.

Stay informed, isolate credentials (via jump-hosts & PAM), and patch the proxy/rathole vectors above before you next refresh system images.