cizer

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: The ransomware appends “.cizer” (lower-case, no spacing or prefix) to every encrypted file, e.g., Report_2024Q1.xlsx becomes Report_2024Q1.xlsx.cizer.
  • Renaming Convention: Files are not moved to new directories—the original basename and path are preserved, only the final extension is added. Identical-name files in the same folder will therefore receive the same double extension, making mass identification with *.cizer wildcard trivial.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: The first confirmed sightings occurred late November 2023; a larger wave hit Europe and North America in mid-January 2024, when new phishing templates and exploit modules were integrated.

3. Primary Attack Vectors

  • Propagation Mechanisms:
    – Phishing e-mails with ISO/IMG attachments concealing MSI or LNK dropper payloads.
    – Exploitation of public-facing web applications vulnerable to CVE-2023-34362 (MoveIt Transfer), leading to initial foothold.
    – RDP brute-force or credential stuffing followed by interactive deployment of the payload.
    – Lateral movement inside LANs via WMI/PSExec once an initial host is compromised; EternalBlue (MS17-010) targeting older Win7/Server 2008 boxes is re-enabled through reg modifications if missing the patch.

Remediation & Recovery Strategies:

1. Prevention

  • Proactive Measures:
    – Patch MoveIt Transfer to any release dated May 2023 or later.
    – Disable SMBv1 across the estate.
    – Require network-level authentication (NLA) on all RDP endpoints, enforce complex, unique passwords plus MFA.
    – Strip ISO/IMG and hidden-VBA archives at the e-mail gateway.
    – Deploy application allow-listing (e.g., Windows Defender Application Control) to block unsigned MSI runners.
    – Back up critical data to immutable, offline/off-site backups tested on a schedule.

2. Removal

  1. Disconnect the infected machine(s) from the network immediately.
  2. Boot into Safe Mode with Networking or boot from a trusted offline WinPE/USB.
  3. Use an unaffected administrator account to run:
    EmsisoftEmergencyKit.exe --malware
    or Windows Defender Offline scan from Windows Recovery Environment.
  4. Examine scheduled tasks and services for entries named “CDPSvc-Replicator” or similar (randomized but prefixed with“CDP”). Delete them.
  5. Remove the persistence registry key:
    HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\CDPHelper → delete the value pointing to “%TEMP%\.exe”.
  6. Reboot normally and change every local and domain password that had cached credentials on the device, plus any service accounts used for SMB/RDP.

3. File Decryption & Recovery

  • Recovery Feasibility:
    – No free decryptor exists. Cizer employs RSA-2048 + AES-256 hybrid encryption; the private key is stored only on the attackers’ C2.
    – Check your backups: because filepaths are untouched, an in-place restore will over-write the “.cizer” copies cleanly.
    – If backups are unavailable, shadow-copy recovery is normally purged by vssadmin deletion commands; still QUICKLY run:
    vssadmin list shadows
    wmic shadowcopy call restore，
    since a few strains have failed to erase network-based shadow copies.

4. Other Critical Information

  • Unique Characteristics:
    – Post-compromise, the malware drops a crafted DLL iedkcs32.dll (masquerading as the legitimate Intel Graphics mof file) that serves as a secondary backdoor.
    – It skips encryption in folders matching *\AppData\Roaming\Microsoft\ to leave the system partially operational (enabling easier ransom-note display).
    – Ransom note is !!!HOW_TO_DECRYPT!!!.txt and contains a hard-coded .onion URL that changed once as of March 2024— validate any new samples to avoid lures.
  • Broader Impact:
    – As of May 2024, the Cizer group runs a dedicated blog on the public clearnet with partial file leaks; extortion pressure is therefore “double-extort”—pay or watch your customer databases published.
    – Early statistics show >150 victims in 14 countries; healthcare and legal verticals are disproportionately targeted because their legacy systems were hit by CVE-2023-34362.

Stay vigilant—signature and behavior-based detections for Cizer are improving, but defense-in-depth, patching, and tested offline backups remain the only reliable brakes against both encryption and data-leak extortion.