*[email protected]*,crp

[Content by Gemini 2.5]

As a cybersecurity expert specializing in ransomware, I’ve compiled a comprehensive resource on the ransomware variant identified by the file extension *[email protected]*,crp. This variant exhibits characteristics consistent with the prolific STOP/Djvu ransomware family, which continuously releases new iterations with unique file extensions and contact emails.

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: The exact file extension used by this variant is *[email protected]*,crp. This indicates that [email protected] is likely the contact email address provided by the attackers, and crp is the specific four-letter (or in this case, three-letter) extension appended after the contact email.
  • Renaming Convention: This ransomware follows a typical pattern for STOP/Djvu variants. It encrypts files and appends the specific extension to the original filename. The renaming pattern will generally be:
    [original_filename][email protected],crp
    For example, document.docx would become [email protected],crp, and photo.jpg would become [email protected],crp.
    Additionally, a ransom note, typically named _readme.txt, is dropped in every folder containing encrypted files.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: While a precise “start date” for *[email protected]*,crp as a standalone unique variant is difficult to pinpoint due to the continuous nature of STOP/Djvu releases, variants using the [email protected] email and similar extensions are part of the ongoing wave of new Djvu builds. This particular combination ([email protected],crp) would have likely emerged and been detected recently, typically in the late 2023 to early 2024 timeframe, as part of the daily emergence of new Djvu strains. The STOP/Djvu family itself has been active since late 2018 and is one of the most widespread consumer-level ransomware threats.

3. Primary Attack Vectors

This variant, like other STOP/Djvu ransomware strains, primarily relies on social engineering and deceptive distribution methods:

  • Cracked Software and Illicit Downloads: The most common vector involves victims downloading “cracked” versions of popular software (e.g., Photoshop, Microsoft Office, video games), key generators (keygens), or software activators from unofficial websites, torrents, or file-sharing platforms. The ransomware executable is often bundled within these downloads.
  • Malicious Advertisements (Malvertising): Compromised ad networks or fake advertisements can redirect users to malicious websites or directly trigger drive-by downloads of the ransomware.
  • Fake Software Updates: Pop-ups or deceptive websites prompting users to update common software (e.g., Flash Player, Java, web browsers) can deliver the ransomware.
  • Phishing Campaigns (Less Common for Djvu): While less prevalent than cracked software, targeted phishing emails containing malicious attachments (e.g., seemingly legitimate documents with embedded macros) or links to compromised websites can also be used.
  • Remote Desktop Protocol (RDP) Exploits: While Djvu typically targets individual consumers, some variants can be deployed via brute-forcing weak RDP credentials, especially if the infected machine is also used for business purposes. However, this is not its primary propagation mechanism.

Remediation & Recovery Strategies:

1. Prevention

  • Regular Backups: Implement a robust 3-2-1 backup strategy (3 copies, on 2 different media, with 1 offsite/cloud). Ensure backups are isolated from the network to prevent encryption.
  • Strong Antivirus/Anti-Malware Software: Use a reputable, up-to-date endpoint protection solution with real-time scanning and behavioral analysis capabilities.
  • Software Updates & Patching: Keep operating systems, applications, and all software (especially web browsers and their plugins) fully patched to close known security vulnerabilities.
  • User Education: Train users to recognize phishing attempts, avoid downloading cracked software, and be wary of suspicious links or attachments.
  • Disable Unnecessary Services: Turn off RDP if not needed, or secure it with strong, unique passwords, multi-factor authentication (MFA), and network-level authentication (NLA).
  • Firewall Rules: Configure firewalls to block outbound connections to known malicious IP addresses and restrict unnecessary inbound traffic.
  • Ad Blockers: Use browser extensions to block malicious advertisements.

2. Removal

  • Isolate the Infected System: Immediately disconnect the infected computer from the network (both wired and Wi-Fi) to prevent the ransomware from spreading to other devices.
  • Identify the Ransomware Process: Use Task Manager or a process explorer tool to identify suspicious processes. Often, Djvu processes run from the AppData\Local or ProgramData folders.
  • Boot into Safe Mode: Restart the computer in Safe Mode with Networking. This often prevents the ransomware from fully executing.
  • Run Full Scans: Use your updated antivirus/anti-malware software to perform a full system scan. Reputable tools will detect and quarantine or remove the ransomware executable.
    • Recommended Tools: Malwarebytes, ESET, Bitdefender, Sophos, or your existing endpoint protection.
  • Check for Persistence Mechanisms: Manually inspect common persistence locations (e.g., Registry Run keys, Startup folders, Scheduled Tasks) for entries related to the ransomware and remove them.
  • Do NOT Pay the Ransom: There is no guarantee that paying the ransom will result in file decryption, and it encourages further ransomware attacks.

3. File Decryption & Recovery

  • Recovery Feasibility: Decrypting files encrypted by *[email protected]*,crp (like other STOP/Djvu variants) depends heavily on whether the encryption occurred using an “online” or “offline” key.
    • Online Key: If the victim’s computer had an active internet connection during encryption, the ransomware generates a unique “online key” for that specific infection. This key is stored on the attacker’s server and is not recoverable by researchers. In this scenario, decryption is generally not possible without obtaining the key from the attackers (which is not recommended).
    • Offline Key: If the victim’s computer was offline during encryption, the ransomware uses a static “offline key” which is hardcoded into the ransomware executable. If researchers have previously recovered this specific offline key from another infection, then decryption might be possible for files encrypted with that key.
  • Essential Tools/Patches:
    • Emsisoft Decryptor for STOP Djvu Ransomware: This is the primary and most effective tool for attempting decryption of STOP/Djvu variants. It contains a repository of known offline keys and can identify whether your files were encrypted with a known offline key.
      • How it works: You run the decryptor, select your encrypted files/folders, and it attempts to match the encryption ID to known keys. If a match is found (for an offline key), it can decrypt your files. If an “online ID” is detected, decryption is typically not possible.
    • Shadow Volume Copies (VSS): While STOP/Djvu ransomware typically deletes Shadow Volume Copies using vssadmin.exe Delete Shadows /All /Quiet, it’s still worth checking if they exist using tools like ShadowExplorer. If they weren’t deleted, you might be able to restore previous versions of your files.
    • Data Recovery Software: For highly valuable files, you can attempt to use data recovery software (e.g., PhotoRec, R-Studio, EaseUS Data Recovery) to scan your drive for unencrypted remnants of the original files. This is a long shot as the ransomware typically overwrites data, but sometimes partial recovery is possible.
    • System Restore Points: If system restore was enabled and not deleted, you might be able to revert your system to a state before the infection, but this will not decrypt files already encrypted.

4. Other Critical Information

  • Additional Precautions:
    • Preserve the Ransom Note (_readme.txt): This file contains critical information, including your personal ID and sometimes the contact email. This ID is essential for tools like the Emsisoft Decryptor.
    • Do NOT Modify Encrypted Files: Modifying or renaming encrypted files can make them irrecoverable, even if a decryption key becomes available.
    • Report the Incident: Report the ransomware attack to your local law enforcement or cybersecurity authorities (e.g., IC3 in the US, Action Fraud in the UK). This helps in tracking threat actors and developing defensive strategies.
    • Consider Professional Help: If you’re a business or an individual with critical data, consider engaging a professional incident response firm.
  • Broader Impact:
    • Data Loss: The most immediate and significant impact is the potential for permanent loss of valuable personal or organizational data if decryption is not possible and backups are inadequate.
    • Operational Disruption: For businesses, ransomware attacks can lead to significant downtime, impacting productivity, revenue, and customer service.
    • Financial Costs: Recovery efforts, potential IT contractor fees, and the cost of replacing compromised systems can be substantial.
    • Reputational Damage: Especially for businesses, a ransomware attack can damage trust with customers and partners.
    • Psychological Stress: For individuals, the loss of personal memories (photos, videos) and documents can cause significant emotional distress.

This variant, like its many Djvu brethren, preys on unsuspecting users through deceptive means. Proactive prevention and understanding recovery limitations are key to mitigating its impact.