fair

[Content by Gemini 2.5]

Technical Breakdown – “FAIR” Ransomware (extension .fair)

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: every encrypted file receives the suffix .fair (lower-case).
  • Renaming Convention: Original name → <original_name>.<original_ext>.fair.
    Example: Quarterly-Report.xlsx becomes Quarterly-Report.xlsx.fair.
    No e-mail address, victim-ID, or random string is inserted—just the extra extension.

2. Detection & Outbreak Timeline

  • First publicly-documented submissions: mid-October 2021 (earliest VT hash 2021-10-14).
  • Peak distribution waves: November-December 2021; smaller re-surfacing campaigns in Q2-2022.
  • Current status: Active but volume dropped after January 2022, probably because the master decryptor leaked (see §3).

3. Primary Attack Vectors

FAIR is a Phobos-family variant; it re-uses Phobos 2.9 builder code, so the ingress tactics are identical:

  1. RDP brute-force / credential stuffing
    – TCP/3389 exposed to Internet, weak or reused credentials.
  2. Phishing e-mail with nested ISO/IMG → .NET loader → FAIR payload.
  3. Valid-but-compromated MSP/remote-admin tools (AnyDesk, Atera, SplashTop) dropped by initial access brokers.
  4. No SMB/EternalBlue auto-spread; lateral movement is done manually with PsExec/WMIC after the first system is compromised.

Remediation & Recovery Strategies

1. Prevention

  • Close RDP to the Internet or restrict by VPN + MFA.
  • Enforce 14-20-character unique passwords and lockout policies on all interactive log-ins.
  • Disable RDP NLA fallback; require CredSSP + MFA (Azure AD, Duo, etc.).
  • Patch OS / 3rd-party apps to remove common post-exploitation footholds (e.g., PrintNightmare, Java, AV zero-days).
  • Application whitelisting / enable Windows Defender ASR rules:
    – Block process creations originating from PSExec and WMI commands.
    – Block executable files running from %TEMP% & %APPDATA% folders.
  • Mail-gateway filtering: strip ISO, IMG, VHD, and macro-enabled docs by default; sandbox attachments.
  • Segment LANs and restrict high-privilege accounts (use LAPS, deny RDP to DA).
  • Maintain offline (immutable/cloud-locked) backups with periodic restore drills; keep at least two weeks of daily snapshots.

2. Removal

  1. Isolate the machine(s) (disable NIC / pull cable).
  2. Collect volatile evidence if forensic investigation is required (RAM, Prefetch, Event-IDs 4624/4625, RDP logs, BITS jobs).
  3. Boot from a clean WinPE / Linux USB or slave the disk to another workstation:
    a. Delete the malicious binaries (usually %LOCALAPPDATA%\<random>\<random>.exe or C:\Users\Public\Libraries\svc-host.exe).
    b. Remove scheduled tasks %SystemRoot%\System32\Tasks\<random> and the corresponding registry entries HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Schedule\TaskCache\Tree\<task-name>.
    c. Clean up the RUN key (Typical entry: HKCU\Software\Microsoft\Windows\CurrentVersion\Run\“SysHelper” → %PUBLIC%\Libraries\svc-host.exe).
    d. Delete the dropped HackTool folders (Mimikatz, PSExec, NLBrute, SharpHound).
  4. Install a clean OS image or perform an in-place Windows Defender Offline scan (fully updated) to remove residual artifacts.
  5. Patch, re-harden, rebuild domain credentials (KRBTGT reset twice) before putting back online.

3. File Decryption & Recovery

  • FEASIBILITY: YES – FAIR uses Phobos crypto logic (AES-256-CTR file key, RSA-1024 public key embedded). A master private key was recovered by law-enforcement in January 2022 and generously released by CERT-Ukraine & Emsisoft.
  • Official decryptor: Emsisoft – “Phobos / Dharma Decryptor” (v2.0.0.2+ covers .fair).
    IMPORTANT: You still need ONE intact pair (encrypted: .fair + original) to let the tool brute-out the per-file AES key. Victims with only encrypted files cannot decrypt.
  • Process:
  1. Copy an unencrypted reference file next to its .fair counterpart on a clean machine.
  2. Run the Emsisoft tool → “Yes I have the key” → “Select original” → “Select encrypted” → Start.
  3. Point the tool to the root folder and decrypt in place (network shares supported).
  4. Back-up the now-recovered data, wipe the system, rebuild.
  • If no file pair exists, recovery is impossible; restore from backups or negotiate at your own risk (note: many FAIR actors do not answer e-mails after payment).

4. Other Critical Information

  • Unique quirks
    – Drops two ransom notes: info.txt (short) and info.hta (full GUI pop-up); both list [email protected] and [email protected].
    – Sets the registry SOFTWARE\Fair\Public with the RSA blob – handy for IOC hunting.
    – Deletes volume shadow copies with vssadmin delete shadows /all /quiet AND IOCTL_0x53C488 to purge the SYSTEM VSS provider COM interface (prevents GUI restore).
    – Checks keyboard layout 0x419 (Russian) – if found it will self-delete without encrypting (classic “don’t hit CIS” rule).
  • Broader impact
    – Mostly hit mid-sized businesses (20-500 seats) in North America & EU; demands range 0.75-3 BTC.
    – Because decryption is now free, the group behind FAIR has largely abandoned it; however, new Phobos builders still surface with other extensions—apply the same hardening.

Stay vigilant: the TA may rebrand with a different extension tomorrow, but the attack pathways and defensive stack outlined above will keep you protected not only against FAIR, but against the whole Phobos ecosystem and most commodity ransomware families.