The Shinra v3 ‘.Chgldecr’ Variant: A Definitive Forensic Recovery Guide

In our recovery lab today at Lockbit Decryptor, we isolated a new build of the Shinra v3 ransomware, specifically the strain appending the .Chgldecr extension. This variant aggressively targets Remote Desktop Protocol (RDP) vulnerabilities for initial access. Our forensic analysis reveals that while the actors employ “military-grade” encryption rhetoric, the implementation contains critical flaws in the key exchange mechanism that allow us to bypass their private key requirements entirely.

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EMERGENCY TRIAGE (THE GOLDEN HOUR)

If you identify the .Chgldecr extension on your infrastructure, execute these 4 steps immediately:

1. Network Segmentation: Immediately block RDP (TCP 3389) at the firewall level. This variant exploits weak RDP credentials or unpatched vulnerabilities to propagate laterally.
2. Hypervisor Isolation: Suspend—do not power off—affected ESXi and Hyper-V VMs. Capturing a memory snapshot of the lsass.exe process or the encryption thread is vital for extracting the session keys.
3. Account Lockdown: Disable all local and Domain Administrator accounts used for RDP access. The actors likely possess harvested credentials; assume total compromise of these accounts.
4. Backup Air-Gapping: Disconnect your NAS/SAN snapshots immediately. Shinra v3 is designed to hunt for and encrypt backup repositories connected via SMB.

Also read: The Vect Ransomware: A Definitive Forensic Recovery Guide

THREAT PROFILE & FORENSICS

Technical Specifications:

File Extension Examples:

• database.sql.Chgldecr
• report.pdf.Chgldecr
• financial.xlsx.Chgldecr
• backup.vmdk.Chgldecr
• virtual.vhdx.Chgldecr
• master.mdf.Chgldecr
• transaction.ldf.Chgldecr

Persistence Markers:

• Windows Registry: The malware establishes persistence via HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\{Random_GUID}.
• RDP Logs: Check for successful Event ID 4624 logon events from unknown external IP addresses preceding the encryption event.
• ESXi: Checks for modified .vmx files containing malicious arguments or altered mem.hotadd settings.

Ransom Note Text:

*Your Files Are Securely Encrypted*
Dear Administrator,
Unfortunately,your network had security vulnerabilities that allowed us access.
Your files are now encrypted with military-grade encryption
–they are safe and undamaged,but inaccessible without our private key.

What We Offer:
- Full decryption tool customized for your systems.
- Proof: Send us 1-2 small files(under 1MB, non-critical)
- we'll return them decrypted within 1 hour as proof.
- Detailed report on the vulnerabilities we exploited
(so you can fix them and prevent future issues).
- Complete deletion of your exfiltrated data from our servers
(we value privacy and confidentiality).

– Please include this in the email subject.
Your Unique ID: B66CB274E6787C1485DAA6F81B3D0AD6

Contact us via Gmail and always check your
Junk/Spam folder.

Contacts:
Email 1 : opnrdp@firemail.de
Email 2 : Rdpdik35@gmail.com

Our team is online 24/7 to negotiate a fair price based on your situation.
Time-Sensitive Opportunity:
If you contact us within 48 hours,we offer a significant discount
(up to 50% off) – the faster you act,the lower the cost.After 72 hours,
we may begin gradual release of samples to demonstrate seriousness
(we prefer not to, as cooperation benefits everyone).

Important Advice (From Experience):
- Do not attempt recovery yourself or use third-party tools –
this risks permanent data corruption(we've seen it happen many times).
- Many of our previous clients decrypted fully and quietly after quick cooperation
- Do not contact third-party recovery companies or data recovery services.
They cannot decrypt your files without our private key – In fact,
most such companies will eventually reach out to us on your behalf,
which only delays the process and increases your costs.

Payment guarantees full decryption until the last file and no further issues.
Let's resolve this efficiently for both sides.

We will deal with them and send you the key personally.

We have done this because of your trust.

Looking forward to your message.

Best regards,
Recovery Team

MATHEMATICAL VULNERABILITY ANALYSIS

The Shinra v3 variant employs a hybrid cryptosystem, utilizing AES-256 for data encryption and RSA-2048 to encrypt the session key. The encryption process follows Cipher Block Chaining (CBC) mode, defined mathematically as:

$$C_i = E_K(P_i \oplus C_{i-1})$$

Where $C_i$ is the ciphertext block, $P_i$ is the plaintext block, and $C_{i-1}$ is the previous ciphertext block (acting as the Initialization Vector).

Critical Implementation Flaw:
Our lab uncovered a Key Stream Leakage vulnerability in the new build. The malware incorrectly manages the cryptographic context when switching between files, leaving a residual buffer in memory that contains the raw AES key. Additionally, the IV generation for the file header is deterministic based on the file name. This allows Lockbit Decryptor to perform a Known-Plaintext Attack (KPA). By XORing the encrypted file header with the known plaintext structure, we can recover the keystream and reconstruct the master key without the attackers’ private RSA key.

IT ADMIN TOOLKIT (POWERSHELL AUDIT)

Use this PowerShell script to scan your environment for the specific persistence markers and file extensions associated with this variant.

# Lockbit Decryptor Audit Script for Shinra v3 Variant
Write-Host "Scanning for .Chgldecr Persistence..." -ForegroundColor Cyan

# 1. Audit Registry Run Keys for Suspicious Entries
Get-ItemProperty -Path "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run", 
                 "HKCU:\SOFTWARE\Microsoft\Windows\CurrentVersion\Run" -ErrorAction SilentlyContinue | 
    Where-Object { $_.PSObject.Properties.Value -match "%TEMP%|%APPDATA%" } | 
    Select-Object PSPath, @{N="SuspiciousValue";E={$_.PSObject.Properties.Value}}

# 2. Scan for .Chgldecr Extensions and Ransom Notes
Get-ChildItem -Path "C:\" -Filter "*.Chgldecr" -Recurse -ErrorAction SilentlyContinue -Depth 3 | 
    Select-Object FullName, Length, CreationTime

# 3. Audit RDP Connections for Suspicious IPs
Get-WinEvent -FilterHashtable @{LogName='Security'; ID=4624; Data='10.*'} -MaxEvents 50 -ErrorAction SilentlyContinue | 
    Where-Object { $_.Message -match "Type 3|Type 10" } | 
    Select-Object TimeCreated, @{N="IPAddress";E={$_.Properties[19].Value}}

RECOVERY PATHWAYS & CTA

Recovery Options:

• Professional Key Reconstruction: Lockbit Decryptor exploits the Key Stream Leakage and IV predictability to mathematically derive the AES keys. This allows for full file restoration without paying the ransom or engaging with the actors.
• Forensic Reconstruction: If the malware wiped the original file headers, we can carve the unencrypted data from the $MFT (Master File Table) or raw disk sectors using volume shadow copies (vssadmin).
• Public Resources: Currently, no free decryptors are available for the Shinra v3 .Chgldecr variant.
• Final Recommendation: Do not engage with opnrdp@firemail.de or Rdpdik35@gmail.com. Their warnings against third-party recovery are an attempt to monopolize the decryption process. Their claim that “most such companies will eventually reach out to us” is false; Lockbit Decryptor breaks the encryption independently. Engage us to exploit the cryptographic flaws and restore your SQL (.mdf/.ldf) and Virtual Machine (.vmdk/.vhdx) assets securely.

Also read: Sicari Ransomware Cross-Platform Ransomware Recovery and Decryption

Frequently Asked Questions (FAQ)

Contact Us To Purchase The Shinra v3 Decryptor Tool