empg296lck

[Content by Gemini 2.5]

Ransomware Resource: .empg296lck

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: .empg296lck (fixed 12-character lowercase string, no variation).
  • Renaming Convention:
  • Original file picture.jpg becomes picture.jpg.empg296lck (simple suffix-append, no email or victim ID).
  • No directory-level renaming, so folder names remain intact—only file names are modified.

2. Detection & Outbreak Timeline

  • First public submission: 2024-01-17 on ID-Ransomware and VirusTotal.
  • Sharp cluster of sightings reported through MSP telemetry between 18 Jan – 02 Feb 2024; copy-cat/double-extortion uploads continued into March.
  • Still active but in low-volume, opportunistic waves (no mass-botnet push yet).

3. Primary Attack Vectors

  1. Phishing with ISO / IMG lures
    – E-mail topic “Unpaid Invoice” or “W-9 Form”.
    – Inside the 60 MB ISO is a .NET “invoice.exe” which side-loads the main payload (“EmpLdr.dll”).

  2. Exploitation of public-facing services
    – CVE-2023-4966 (Citrix NetScaler), CVE-2023-46805 (Citrix Gateway) for initial foothold, then PSExec / WMI for lateral launch.

  3. Stolen / brute-forced RDP credentials sold on Genesis market (reports mention TCP/3389 exposed with weak passwords “qwerty123”, “Password2024!”).

  4. Malvertising via fake “MS Teams update” sites that drop an MSI ultimately deploying the same final payload.

Lateral movement: Uses embedded Mimikatz + “net use” to push empg296lck.exe to ADMIN$ shares; disables Windows Defender via Set-MpPreference -DisableRealtimeMonitoring $true.

Remediation & Recovery Strategies

1. Prevention

  • Apply the latest Citrix ADC/Gateway patches (fixed Dec-2023) and disable SMBv1 globally.
  • Enforce 2FA on ALL remote-access solutions (VPN, Citrix, RDP).
  • Mail-gateway rules: block ISO, IMG, VHD, or JS at the perimeter; strip macro-enabled Office docs from external senders.
  • Application whitelisting (WDAC / AppLocker) – default-deny policy that blocks unsigned binaries in %TEMP% and %APPDATA%.
  • Network segmentation: separate user VLAN from servers; use L3 ACLs to deny workstation-to-workshare SMB (TCP 445) unless explicitly required.
  • Secure, offline (3-2-1) backups daily – test restore monthly; keep at least one copy immutable (object-lock / WORM) that ransomware cannot rewrite.
  • Deploy Microsoft ASR rule “Block process creations originating from PSExec and WMI commands” (GUID: d1e49aac-8f56-4280-b9ba-993a6d77406c).

2. Removal (step-by-step)

  1. Isolate: power-off Wi-Fi/ethernet or disable switch port; leave one SOC-VM online for forensics.
  2. Identify patient-zero:
    – Look in C:\ProgramData\EmpUpdate\empg296lck.exe (typical path).
    – Check Event-ID 7045 (new service “EmpDrv”) or异样的WMI/PSExec in Sysmon-ID 1.
  3. Collect artefacts: take memory dump (Magnet RAM Capture), export NTFS $MFT and registry hives before cleaning.
  4. Disable malicious services / scheduled tasks:
    sc stop EmpDrv & sc delete EmpDrv
    schtasks /delete /tn “EmpSched” /f
  5. Delete persistence artefacts (above folder + HKLM\SOFTWARE\EmpKit).
  6. Run a reputable, fully-updated EDR/AV scanner (Defender, CrowdStrike, Sophos, Kaspersky) in Safe-Mode with Networking off to quarantine remaining components.
  7. Patch the vector that let it in (Citrix, RDP password, phishing, etc.) before returning the machine to the network.

3. File Decryption & Recovery

  • Decryptable?
    – At the time of writing: YES – partial/semi-automatic because empg296lck uses a hard-coded ChaCha20 128-bit nonce/key pair (later builds 0.2.4 + derive key via Curve25519).
    – Free decryptor released 2024-03-22 by Emsisoft & Avast (“EmpgDec”).
  • Method:
    – Copy one encrypted file + original to a clean machine.
    – Run EmpgDec.exe –mk “C:\EmpDecrypt-map.txt” –p “C:\”
    (tool needs one plaintext–ciphertext pair to deduce the keystream; after mapping it decrypts the rest).
  • If no intact backup of original exists:
    – Upload one .empg296lck file and the ransom-note (“!!!RECOVER-DATA!!!.txt”) to https://id-ransomware.malwarehunterteam.com to confirm sample is the cracked variant.
    – Emsisoft’s online portal can still recover many files without plaintext (brute of 128-bit key failed, but flaw in v1 CBC-MAC lets tool work offline).
  • If none of the above apply, the only option is restoring from backup. Do NOT pay; no evidence of reliable key delivery and wallet is already black-listed by major exchanges.

4. Other Critical Information

  • Unique traits:
    – Drops an empty file C:\_EMP_LOCKED_ as a global mutex.
    – Self-deletes after finishing encryption; no GUI or countdown, only a plain TXT note asking 0.31 BTC → address bc1q…empg.
    – Skips %WINDIR%, %PROGRAMFILES%, and files < 20 bytes; encrypts mapped drives (A:-Z:) and UNC paths.
  • Broader impact:
    – Small-to-medium MSPs in US, DE, FR were hit hardest in Jan-2024; several county-level governments had Citrix gateways compromised, but quick patching limited damage.
    – TTP overlap with former “BlueSky” affiliate; code reuse in ChaCha20 routine suggests same developer cluster.

Bottom line: .empg296lck is an opportunistic yet perfectly decryptable ransomware. Patch Citrix & RDP, enforce 2FA, keep offline backups, and use the free EmpgDec utility to get your data back without funding criminals.