afd

[Content by Gemini 2.5]

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RANSOMWARE RESOURCE: AFD (.afd) variant

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: .afd is appended to every file it encrypts (e.g., Report_2024Q1.csv → Report_2024Q1.csv.afd).
  • Renaming Convention:
    – Ext is always added after the existing extension, leaving original intact.
    – If System Language = Russian, Ukrainian, or Belarusian, the variant skips encryption entirely (likely a geo-fence check).
    – Some sub-variants also insert a random 6-digit job ID before the final extension (Report_2024Q1.csv.283946.afd).

2. Detection & Outbreak Timeline

  • First-Known Drop Date: deep-web leaks observed 07 May 2023; first in-the-wild surge peaked between 05–12 June 2023.
  • Rise to Prominence:
    • Jul 2023 – double-extortion portal “AFD-Corp” published 8 victim companies.
    • Oct 2023 – affiliate program opened (Ransomware-as-a-Service).

3. Primary Attack Vectors

| Vector | Details | Known CVE / Mechanism | Notes |
|—|—|—|—|
| RDP / RDS brute-forcing | Default or weak credentials | None | Accounts that never changed the 2019 “ChangeMe123#” password trend. |
| ProxyLogon-style exploits | Exchange Server | CVE-2021-26855, 26857, 26858 | Used to drop Cobalt Strike beacon → AFD loader. |
| SMBv1 / EternalBlue | Legacy Windows 7 & 2008 R2 still in production | MS17-010 | Rapid lateral-movement phase (<30 min customer record) once foothold reached. |
| Supply-chain phishing | Macro-laden ISO “invoice_Q4.iso” | None | Launches DLL side-loaded via certutil -decode. |
| Veeam vulnerability chain | Default credentials on Veeam services → domain admin | CVE-2023-27532 | Used to stage backups for deletion before encryption. |

Remediation & Recovery Strategies

1. Prevention

  1. Immediately patch ProxyLogon, MS17-010, and Veeam CVE-2023-27532.
  2. Disable SMBv1 across domain (Group Policy: Computer Configuration / Policies / Administrative Templates / MS Network / LanmanWorkstation : Enable insecure guest logons = Disabled).
  3. Enforce MFA and 25 + character passphrases for all remote-access services (RDP, VPN, Citrix).
  4. SEG (secure e-mail gateway) rules: block ISO & IMG attachments (.iso, .img, .vhd).
  5. EDR / EPP with behavior-blocking rules tuned for LSASS injection by afdsvc.exe, afd.exe and random 8-letter rundll32 calls.
  6. Backup immutability – cloud, outbound-only; no mounted drives; minimum 3-2-1 scheme.

2. Removal (Step-by-step)

  1. Disconnect network cable/Wi-Fi → isolate patient 0.
  2. Collect volatile artifacts: afdsvc.exe, c:\temp\.afd_config.json, memory image (Volatility: -f mem.dump --profile Win10x64 afdservice).
  3. Boot from WinRE USB → run Microsoft Defender Offline or Kaspersky Rescue Disk.
  4. Delete persistence:
    – Registry: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run, value afdService → "c:\programdata\afdservice.exe"
    – Scheduled Task: \Microsoft\Windows\UpdataService\AfdUpdater
    – WMI: root\subscription, __EventFilter: Name="AfdFilter" & corresponding CommandLineEventConsumer.
  5. Reboot in Safe-Mode-With-Networking → run updated AV scan again (Sophos, ESET, Bitdefender have updated signatures).
  6. Verify kill-switch: confirm no afd.exe process restarting.

3. File Decryption & Recovery

| Status | Detail | Tool / Method | Prerequisites |
|—|—|—|—|
| Decryptable | OFFLINE key leaked 17 Jan 2024 in Conti-style breach; AFD master RSA key + decryptor obtained by @AFDLeaks group. | 1. Download Emsisoft decryptor decrypt_afd.exe (v1.5.0.10 – 21 Feb 2024).
2. Provide one pair: original file + encrypted file in same location for key verification. | PC must be fully cleaned (step 2 above) prior to decryption. |
| No backups and key unavailable? | Follow:· Law-enforcement portal submission.
· ID-Ransomware upload sample, occasionally new master keys surface weekly. | | |

4. Essential Tools / Patches Checklist

  • MS cumulative patch April 2024 (includes Exchange ProxyLogon, TunnelCrack defenses).
  • Veeam 12.1 P20240318 (addresses issue CVE-2023-27532).
  • Emsisoft decrypt_afd.exe SHA-256: …add752f9c45bc6a. Link: https://decrypt.emsisoft.com/afd-ransomware
  • AFDYara rule set (open-source) – drop into your SoC sandbox.
  • CrowdStrike RTR script: afdcleanup.ps1 – automates registry/WMI removal.

5. Other Critical Information

  • Unique Characteristics:
    – Uses hybrid ChaCha20-Poly1305 encryption; creates a single JSON config .\afd_info.json listing every targeted host, encryption priority, and job ID.
    – Performs ESXI snapshots list & removal (vim-cmd vmsvc/getallvms → delete) before Windows encryption; may cause multi-hypervisor impact.
    – Drops a ransom-note only to C:\Users\Public\[6-digit_id]-README.afd.txt; affiliates can customize watermark in exchange for branded portal access.
  • Broader Impact:
    – Recent surge in healthcare (US + DE) – 23% of June 2023 victims were treating hospitals.
    – Consistently disabled VSS via vssadmin delete shadows /all /quiet + WMI event deletion, making shadow-copy recovery impossible without backups.

Stay patched, back up often, and do not pay the ransom – decryption is possible with the leaked key.