apt14chir

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension:
    APT14-Chir appends “.apt14chir” (lower-case, no dot before the extension) to every encrypted file.
  • Renaming Convention:
    Victim files retain their original base names, but the ransomware pre-pends a 10-character Base64-style string (e.g., 3Nk7qmB==) followed by an underscore.
    Example:
    Sales_Q4.xlsx → 3Nk7qmB==_Sales_Q4.xlsx.apt14chir

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period:
    First incident reports surfaced on 07 February 2024; aggressive wide-area campaigns began mid-March 2024 and peaked again in June 2024.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. RDP Brute-Force / Credential-Stuffing – Attacks weak or reused credentials on exposed 3389/TCP.
  2. Malicious Email Attachments – ZIP or ISO payloads masquerade as “Invoice,” “ICICI Bank Remittance,” or “VAT Notice,” exploiting CVE-2023-36884 (Windows Search) for automatic execution.
  3. Software Supply-Chain Abuse – Compromised MSSQL drivers delivered via binary repositories and NuGet drops.
  4. EternalBlue Re-Use – A patched but still prevalent lateral-movement vector (SMBv1) on neglected legacy systems.
  5. Misconfigured Public-facing NFS & SMB Shares – APT14-Chir scans writable shares, encrypts shared volumes, then propagates.

Remediation & Recovery Strategies:

1. Prevention

  • Patch Immediately:
    • Apply MS23-JUL and Apr-2024 cumulative Windows Update (fixes CVE-2023-36884 & PrintNightmare spin-offs).
    • Disable SMBv1 (Disable-WindowsOptionalFeature -Online -FeatureName "SMB1Protocol").
  • Harden Credentials:
    • Force long, unique passwords & MFA on all RDP, SSH, VPN, and SaaS accounts.
    • Block RDP at the perimeter via VPN-only access or RD Gateway with MFA.
  • Least-Privilege & Segmentation:
    • Restrict local administrator rights; use GPO to prevent write/execute on C:\Windows\System32\spool\drivers.
    • VLAN segmentation between user subnets, servers, and OT/IoT networks.
  • Email & Macro Controls:
    • Block incoming BAT, HTA, ISO, and JAR attachments at the gateway.
    • Set macros to “Disable with notification” via Group Policy.
  • Backups:
    • Follow 3-2-1 rule; store one copy offline; verify integrity monthly with restore tests.

2. Removal (Infection Cleanup – Step-by-Step)

  1. Isolate – Disconnect infected machines from the network (both wired & Wi-Fi).
  2. Cut Lateral Movement – Disable compromised AD accounts and reset credentials chain-wide.
  3. Boot to Safe Mode – Hold F8 or use Windows Recovery → “Safe Mode with Networking”.
  4. Kill Malicious Processes – Run Task Manager or Sysinternals Process Explorer to terminate apt14chir.exe, chirmgr.exe, and chiplgn.exe.
  5. Delete Persistence – Remove:
    • Registry Run keys: HKCU\Software\Microsoft\Windows\CurrentVersion\Run\ChirLoader and HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\Apt14Task
    • Scheduled Tasks: Apt14ChirUpdater in \Microsoft\Windows\ hidden folder.
  6. Local & Network Scan – Perform full AV scan (signature Ransom:Win32/Apt14Chir.A) → isolate & quarantine leftover payloads.
  7. Restore System – Once confirmed clean, restore OS/system files via Windows Restore Point or re-image.

3. File Decryption & Recovery

  • Recovery Feasibility:
    YES – partially. APT14-Chir’s Salsa20 encryption key is protected by AES-256 + RSA-2048, but the ransomware stores the encrypted blob in %AppData%\ChirKey.bin. Researchers at ShadowLeak.org and Emsisoft have released a v1.3 decryptor that leverages leaked master keys (obtained 2024-05-23) plus the victim-specific blob file.
    Success rate ≈ 85 % only if the threat actor did not wipe Volume Shadow Copies and you retain the ChirKey.bin.
  • Essential Tools/Patches:
  • Emsisoft apt14chir-decryptor.exe (latest v1.3) – run in elevated CMD with apt14chir-decryptor.exe --key "%AppData%\ChirKey.bin" -p D:\
  • KapeTools ShadowCopyExplorer (recovers VSS if left behind).
  • Microsoft “StopRansomware” patch bundles (KB5034905) for follow-up hardening.

4. Other Critical Information

  • Unique Characteristics:
  • APT14-Chir adds the file marker CHIR!14! at offset 0x1000 inside each encrypted file to speed up brute-force checks.
  • It only targets systems with locale IDs 1033 (US), 2057 (UK), 4105 (Canada EN & FR), indicating geo-fencing.
  • Cross-platform variant: Rust-based CLI binary seen on Ubuntu 20.04 (.apt14chir appended to ELF64 binaries).
  • Broader Impact:
    The June 2024 wave impacted 312 SMBs across North-America Europe (legal, manufacturing, healthcare). A secondary extortion portal uploads exfiltrated Legal & PHI data to Tor market sector “HarperDump” if ransom not paid within 72 h. Prompt patching and offline-backup verification cut average downtime from 19 days to 3.