RedStar (.RedStar) ransomware virus decryption options

In our recovery lab today at Lockbit Decryptor, we isolated the RedStar ransomware strain. Our analysis confirms this is not a sophisticated enterprise-grade threat but a variant of the open-source HiddenTear ransomware. This variant uses a simple XOR cipher with a hard-coded key, appending the .RedStar extension. Despite its playful ransom note, the encryption is trivially reversible, allowing for complete file recovery without any actor interaction.

Latest: The Proton (.bricks) Variant: Bricks Decryptor and Recovery

EMERGENCY TRIAGE (THE GOLDEN HOUR)

If you are observing the .RedStar extension on your systems, execute these 4 steps immediately:

1. Network Segmentation: Immediately sever all SMB (TCP 445) and RDP (TCP 3389) connections to prevent the simple script from spreading to other accessible shares.
2. Process Termination: Identify and terminate the ransomware process. It is often a single .exe file with a randomized name running under the user’s context.
3. Malware Removal: Scan the affected system with a reputable antivirus solution to remove the initial dropper and any secondary payloads.
4. Credential Flush: While this variant does not typically steal credentials, it is good practice to rotate passwords for any accounts that were logged in during the infection.

Also read: The BianLian ‘.locked’ (TOSG) Variant: A Definitive Forensic Recovery Guide

THREAT PROFILE & FORENSICS

Technical Specifications:

File Extension Examples:

• database.sql.RedStar
• report.pdf.RedStar
• financial.xlsx.RedStar
• image.jpg.RedStar
• document.docx.RedStar

Persistence Markers:

• Windows Registry: The malware may establish persistence via HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\{Random_GUID}.
• Startup Folder: A copy of the executable may be placed in the user’s Startup folder (%APPDATA%\Microsoft\Windows\Start Menu\Programs\Startup).
• No Hypervisor Persistence: This is a user-level script and does not target ESXi or Hyper-V environments.

Ransom Note Text:

Files have been encrypted with RedStar
Send me some bitcoins or some good coffee.
Contact: [Redstarme@proton.me]

MATHEMATICAL VULNERABILITY ANALYSIS

The RedStar variant uses a simple XOR cipher for encryption. The encryption process for a plaintext byte $P_i$ and a key byte $K_j$ is:

$$C_i = P_i \oplus K_j$$

Where $C_i$ is the ciphertext byte and the key $K_j$ is repeated cyclically.

Critical Implementation Flaw:
The entire encryption scheme is critically flawed due to the use of a Hard-coded Static Key. The XOR key is embedded directly within the malware’s executable code in plaintext. By performing a static analysis on the binary, Lockbit Decryptor can extract this key instantly. Once the key is known, decryption is a simple matter of applying the XOR operation again to the ciphertext:

$$P_i = C_i \oplus K_j$$

This allows for the complete and instantaneous recovery of all encrypted files.

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 RedStar Variant
Write-Host "Scanning for .RedStar 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 .RedStar Extensions and Ransom Notes
Get-ChildItem -Path "C:\" -Filter "*.RedStar" -Recurse -ErrorAction SilentlyContinue -Depth 3 | 
    Select-Object FullName, Length, CreationTime

Get-ChildItem -Path "C:\" -Filter "READ_ME.txt" -Recurse -ErrorAction SilentlyContinue -Depth 3 | 
    Select-Object FullName, CreationTime

RECOVERY PATHWAYS & CTA

Recovery Options:

• Professional Key Extraction & Decryption: Lockbit Decryptor can extract the static XOR key from the malware binary and use it to decrypt all files instantly.
• Public Resources: Free, open-source decryptors for HiddenTear variants are widely available on platforms like GitHub. Any tool capable of analyzing the binary can extract the key.
• Self-Decryption: A technically proficient user can extract the key themselves using a hex editor and then write a simple script to decrypt the files.
• Final Recommendation: Do not contact redstarme@proton.me. This is a low-skill attack using a well-known, broken encryption scheme. Paying is unnecessary. Engage Lockbit Decryptor for immediate file restoration or use a publicly available HiddenTear decryptor. The primary goal should be identifying and removing the initial infection vector.

Also read: The Zollo (.zollo6, .zollo10, .zollo15) Variant of MedusaLocker Decryption and Recovery

Frequently Asked Questions (FAQ)

Contact Us To Purchase The RedStar Decryptor Tool