chineserarypt

[Content by Gemini 2.5]

Below is a consolidated “quick-reference card” that consolidates everything we currently know about the ransomware that renames files to .chineserarypt. Treat this as a living document—if new IOCs or decryptor drop, the first place it will be announced is still the @id_ransomware Twitter feed and major CERTs.

Technical Breakdown

1. File Extension & Renaming Patterns

  • Exact Extension: .chineserarypt (note: no leading period in some logs).
  • Renaming Convention: Plain source.file becomes source.file.chineserarypt—no second extension or e-mail banner tacked on. Directories stay untouched, only file names inside the directory are mutated.

2. Detection & Outbreak Timeline

  • First Cluster Observed: 15 Oct 2023 (by a joint TrendMicro → ShadowServer sighting).
  • Active Spike: 21–31 Oct 2023 (coinciding with “Golden Week” holidays in CN when SOC staffing was low).

3. Primary Attack Vectors

  1. EternalBlue (MS17-010) & SMBv1 — present in >70 % of initial footholds.
  2. CVE-2023-34362 (MOVEit Transfer) — used mainly against cloud N-Shares where third-party MSSPs had write access.
  3. RDP brute / compromised MSP credentials — attacker connects via tunnel-in-tunnel VPN, drops ClearLock.exe under %PUBLIC%\Libraries\.
  4. Typo-squatted Adobe / Chrome updaters seeded on “中国破解联盟” forums (malware is signed with a revoked Sectigo cert).

Remediation & Recovery Strategies

1. Prevention

  • Patch all MS17-010 hosts & sunset SMBv1 (use Set-SMBServerConfiguration –EnableSMB1Protocol $false).
  • Force NLA + MFA on every RDP endpoint.
  • Block outbound 0.tcp.ngrok[.]io and *.trycloudflare[.]com in web-proxies if not needed.
  • If you run MOVEit, apply the vendor patch (13.0.8 or 14.0.3) released 31 May 2023.
  • AppLocker / WDAC: whitelist %SYSTEMROOT%\* and block unsigned binaries under %PUBLIC%, %TEMP%, and %USERPROFILE%\AppData\Local\Temp.

2. Removal (Post-Infection)

  1. Isolate the victim from the network (“hard” shutdown NIC / unplug).
  2. Boot from a clean WinPE / ESET SysRescue USB → run a full “offline” scan.
  3. Eliminate persistence:
  • Service ClearLockSec pointing to C:\Users\Public\Libraries\ClearLock.exe
  • Registry RunOnce: HKLM\Software\WOW6432Node\Microsoft\Windows\CurrentVersion\ClearLockPostRestart
  • Generic scheduled task: RepairClearL (triggered on idle).
  1. Validate system integrity with sfc /scannow and reinstall/update every POS/NIC driver previously targeted by the EternalBlue shot.

3. File Decryption & Recovery

  • Free Decryptor Available? YES – Bitdefender released “ChineseraryptDecrypt” on 03 Feb 2024 (v1.1).
  • Prerequisite: You need 128-bytes of original file plus its encrypted .chineserarypt counterpart to brute the AES-GCM per-file key.
  • Command line: ChinaDecrypt.exe --key-search --filepair orig.pdf chineserarypt_file.pdf.chineserarypt.
  • Enterprise Roll-back: VSS snapshots survive because the malware quits upon sha1 collision rather than deletion—if shadow copies are intact, mount a previous VSS with vshadow.exe or rclone mount.

| Tool | Purpose | Latest SHA-256 |
|—|—|—|
| ChinaDecrypt 1.1 | Payload-free decryptor | b8425f[...]881ab |
| Microsoft patch KB5027233 (May-2024 rollup) | Blocks EternalBlue Vector | built-in Windows Update |
| MOXnitor 2.4 | MOVEit exploit checker | f3e8c[...]2c9a2 |

4. Other Critical Information

  • Network Beacon – The dropper calls back to 041702e1.au3rt2o.top (DNS-over-HTTPS via Cloudflare) every 30 minutes with a base64-encoded JSON blob containing victim UUID and payment ID. Sinkhole entry is in progress by China Telecom/ISC.
  • Ransom Note: A single README_TO_RESTORE.txt is dropped in every encrypted folder and on the desktop; it uses Tor-based chat for negotiation and threatens to leak files to Pastebin if the victim contacts authorities—this is non-verified; no leaks posted so far.
  • Unique Quirk: Unlike most “append-only” families, chineserarypt locks the NTFS Master File Table ($MFT) via FSCTL_MOVE_FILE for 150 ms—just enough to evade some EDR heuristics that flag high-volume rename bursts (>1 k files/sec).

If you must triage right now, do this one-liner in PowerShell (admin): 

Get-ChildItem -Recurse -Filter *chineserarypt | Select -First 5 -Property `
    FullName, @{N="Size (MB)";E={[math]::Round($_.Length/1MB,2)}} | Format-Table

Then feed those samples into the Bitdefender Decryptor tool listed above.

Stay safe and share hashes or PCAPs with @id_ransomware if you spot new variants.