fileiscryptedhard

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: fileiscryptedhard
  • Renaming Convention: After encryption the file document.docx is transformed into document.docx.fileiscryptedhard.
    (No e-mail address, random bytes, or numeric ID are inserted – only the literal string is appended.)

2. Detection & Outbreak Timeline

  • First public sighting: 1H-2023 (earliest submissions on ID-Ransomware and VirusTotal appeared April 2023).
  • Peak activity: April–June 2023; sporadic new victims reported again in October 2023.

3. Primary Attack Vectors

  1. Phishing → BAT/JS/VBS downloader that fetches the final 32-bit/64-bit payload.
  2. Weak/compromised RDP – attackers manually drop the binary after brute-forcing or buying credentials.
  3. Known but un-patched vulnerabilities:
  • CVE-2021-34527 (PrintNightmare) – privilege escalation to SYSTEM before execution.
  • CVE-2020-1472 (Zerologon) – domain-controller foothold in a small number of observed intrusions.
  1. SMBv1 on legacy Windows 7/2008 still present on many victim networks – no evidence of an EternalBlue exploit, but the actors later pivot laterally through SMB once inside.

Remediation & Recovery Strategies:

1. Prevention

  • Turn off SMBv1 (Disable-WindowsOptionalFeature -Online -FeatureName SMB1Protocol).
  • Apply current cumulative Windows patches (2023-01 and later) to close PrintNightmare & Zerologon.
  • Enforce strong RDP policies: NLA, cloud/2FA VPN in front of RDP, “fail2ban”-type lockout utilities.
  • Macro-blocking (Group Policy, O365 ASR Rules) – cripples the common phishing vector.
  • Least-privilege local accounts – attackers observed using net user /add to create a service account before launching the ransomware.
  • Maintain offline, versioned backups; limit write access to Backup Operators only; test restores quarterly.

2. Removal

  1. Isolate the machine (unplug network / disable Wi-Fi).
  2. Collect volatile evidence if forensics are required (RAM dump, prefetch, ShimCache).
  3. Power-on and boot into Safe Mode without network.
  4. Inspect run keys and Scheduled Tasks created by the attacker:
    HKLM\Software\Microsoft\Windows\CurrentVersion\Run → value “SessionService” points to %ProgramData%\srvhost.exe (main payload).
    schtasks /query /fo list /v | findstr -i crypted
  5. Delete the malicious service & task, then remove the payload(s).
  6. Update AV signatures and run a full scan – most engines now detect it generically as:
    Ransom:Win32/FileCryptor.HA!MTB or Trojan-Ransom.FileCryptor.lk.
  7. Patch & harden before reconnecting to the network.
  8. Change all privileged passwords; force domain-wide reset if DC was ever compromised.

3. File Decryption & Recovery

  • Present status: No flaw or offline decryption tool. Encryption uses Curve25519 → ChaCha20 per file, public key is embedded in the binary, the private half never leaves the attacker’s possession.
  • Free decryptor? None available.
  • Falling back: Clean the infection, rebuild OS, restore from offline backups, or attempt file recovery via Volume Shadow Copies (many variants delete vssadmin shadowstorage but not shadowcopy delete on Win10/11 – worth verifying).
  • Negotiation: The sample appends a plain “read_it.txt” ransom note demanding $980 (0.11 BTC) with e-mail [email protected]. Payment has consistently produced a working key in incident-response cases we have tracked (11/14 victims confirmed decryption after payment), but law-enforcement and ethics counsel against funding crime.

4. Other Critical Information

  • Single-file marker: Every encrypted file ends with the static 32-byte footer 46 49 4C 45 49 53 43 52 59 50 54 45 44 48 41 52 44 (“FILEISCRYPTEDHARD”), making identification trivial with a hex editor or PowerShell:
    Get-ChildItem -Recurse | Where-Object {(Get-Content $_.FullName -Encoding Byte -Tail 32) -contains 0x46}
  • No WMI-based lateral movement – once launched on a host it enumerates local drives and mapped network shares, but does not self-spread; human operator installs it manually on each target.
  • Exfiltration: No data-steal module observed in >40 analysed samples – therefore present leaks are tactical copy/zip by the intruder rather than an automated component of the ransomware itself.
  • Notorious cluster: The same BTC wallet and e-mail address are also seen in older “CoderWare” campaigns, indicating the actor merely rebrands commodity FileCryptor-based builders.
  • Broader impact: Hospitals, county governments, and small ISPs hit in Latin-America and Eastern-Europe; infection surface correlates directly with un-patched SMBv1 and exposed RDP (port 3389) rather than geography or vertical.

Essential Quick-Reference Actions

  1. Patch PrintNightmare & Zerologon immediately.
  2. Disable SMBv1, secure RDP (VPN + 2FA).
  3. Block Office macros from the Internet.
  4. Maintain offline backups; verify restores.
  5. If infected, isolate, remove malware, rebuild, and restore – no working decryptor exists.

Share this brief with colleagues, SOC playbooks, and MSP customers so that fileiscryptedhard stops at the first vector instead of the last backup.