*[email protected]*.amber

[Content by Gemini 2.5]

The ransomware variant identified by the file extension *[email protected]*.amber is a relatively new iteration that follows common patterns observed in modern ransomware attacks. Based on the naming convention (especially the [email_address] preceding the unique extension), it strongly resembles variants of the STOP/Djvu ransomware family, which is one of the most prolific and continuously evolving threats.

Here’s a detailed breakdown:

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: The exact file extension used by this ransomware variant is .amber.

  • Renaming Convention: The ransomware encrypts files and appends two primary identifiers to the original filename:

    1. The attacker’s contact email address, often enclosed in square brackets (e.g., [[email protected]]).
    2. The unique .amber extension.

    Typical Renaming Pattern:
    [original_filename].[original_extension].[[email protected]].amber

    Example:

    In addition to file encryption, the ransomware typically drops a ransom note in various directories, often named _readme.txt, which contains instructions for the victim to contact the attackers via the specified email address ([email protected]) for decryption payment.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: While a precise “start date” for the .amber variant specifically isn’t widely published (as new STOP/Djvu variants emerge constantly), the parent STOP/Djvu family has been active since late 2017/early 2018. Variants like .amber typically appear as part of ongoing campaigns, indicating their emergence in mid-to-late 2023 or early 2024. The use of @cock.li as a contact email is a strong characteristic of more recent STOP/Djvu iterations.

3. Primary Attack Vectors

*[email protected]*.amber (like its parent STOP/Djvu family) primarily relies on methods that exploit user vulnerability and lax security practices rather than sophisticated network exploits.

  • Software Cracks/Pirated Software: This is the most prevalent infection vector. Users download cracked versions of popular software, key generators, or activators from unofficial websites. These downloads often contain the ransomware hidden within the executable or installer.
  • Phishing Campaigns: While less common than software cracks for this family, general email phishing campaigns can be used. These emails might contain malicious attachments (e.g., seemingly legitimate documents with embedded macros) or links to compromised websites that host the malware.
  • Malvertising & Drive-by Downloads: Users visiting compromised or malicious websites might trigger a drive-by download where the ransomware is downloaded and executed without explicit user interaction, often through exploiting vulnerabilities in web browsers or their plugins.
  • Exploit Kits: Less frequently, exploit kits (EKs) hosted on compromised websites might be used to silently deliver the ransomware by exploiting unpatched vulnerabilities in a victim’s system or browser.
  • Remote Desktop Protocol (RDP) Exploits: While not the primary vector for STOP/Djvu, weak RDP credentials or unpatched RDP vulnerabilities (e.g., BlueKeep) can be leveraged by attackers who gain access to a system and then manually deploy the ransomware.

Remediation & Recovery Strategies:

1. Prevention

Proactive measures are the most effective defense against *[email protected]*.amber and similar ransomware.

  • Regular, Offsite Backups: Implement a robust 3-2-1 backup strategy (3 copies of data, on 2 different media, with 1 copy offsite/offline). This is the single most important defense, allowing recovery without paying a ransom. Test backups regularly.
  • Software Updates & Patching: Keep operating systems (Windows, macOS, Linux), web browsers, and all installed software (especially third-party applications like Adobe products, Java, web servers) fully updated with the latest security patches.
  • Strong Password Policy & MFA: Enforce strong, unique passwords for all accounts. Implement Multi-Factor Authentication (MFA) wherever possible, especially for RDP, VPNs, and cloud services.
  • Endpoint Detection & Response (EDR)/Antivirus: Deploy reputable antivirus/anti-malware software with real-time protection and keep its definitions updated. EDR solutions provide more advanced threat detection and response capabilities.
  • Email Security: Use email filtering solutions to block malicious attachments and links. Train users to recognize phishing attempts.
  • Network Segmentation: Isolate critical systems and data on separate network segments to limit lateral movement in case of a breach.
  • Disable Unnecessary Services: Turn off RDP if not needed, or restrict access to it via VPN and strong firewalls if it is. Disable SMBv1.
  • User Awareness Training: Educate employees about the dangers of clicking suspicious links, opening untrusted attachments, and downloading software from unofficial sources. Emphasize the risks of using pirated software.
  • Application Whitelisting: Implement application whitelisting to prevent unauthorized executables (like ransomware) from running on endpoints.
  • Firewall Configuration: Configure firewalls to block unnecessary inbound and outbound connections.

2. Removal

If infected, swift and careful removal is crucial to prevent further damage.

  1. Isolate the Infected System: Immediately disconnect the infected computer from the network (unplug Ethernet cable, disable Wi-Fi). This prevents the ransomware from spreading to other systems or encrypting network shares.
  2. Identify the Ransomware: Note the ransom note name (_readme.txt), the contact email ([email protected]), and the file extension (.amber). This information is vital for identifying the specific variant.
  3. Boot into Safe Mode: Restart the computer and boot into Safe Mode with Networking (if you need to download tools) or Safe Mode without Networking. This loads only essential services, often preventing the ransomware from fully operating.
  4. Run Full System Scans: Use reputable antivirus/anti-malware software (e.g., Malwarebytes, ESET, Bitdefender, Sophos) to perform a full system scan. Ensure the definitions are up-to-date (if in Safe Mode with Networking, update definitions first).
  5. Remove Detected Threats: Allow the security software to quarantine or remove all detected malicious files.
  6. Check for Persistence Mechanisms: Manually inspect common persistence locations (e.g., Windows Registry Run keys, Startup folders, Scheduled Tasks) for any entries related to the ransomware.
  7. Change All Passwords: After confirming the system is clean, change all passwords used on or accessed from the infected machine (e.g., email, banking, social media, network shares, cloud services).
  8. Re-evaluate Security: Review your overall security posture and implement stronger prevention measures to avoid future infections.

3. File Decryption & Recovery

  • Recovery Feasibility: For *[email protected]*.amber (a STOP/Djvu variant), decryption without the private key is generally not possible for files encrypted with “online keys.” Most modern STOP/Djvu infections use online keys, which are unique for each victim and require the key generated by the attackers.
    • Offline Keys: In rare cases, if the infected system had no internet connection during the encryption process, the ransomware might use an “offline key.” If this specific offline key has been discovered and published by security researchers (e.g., Emsisoft), then decryption might be possible.
    • Emsisoft Decryptor: The Emsisoft Decryptor for STOP/Djvu Ransomware is the primary tool that offers hope for victims. It continuously updates its database with known online and offline keys. You should download and run this tool as a first step. It will attempt to identify the key used and decrypt your files. However, success is not guaranteed, especially for newer variants using online keys.
    • No More Ransom Project: Check the “No More Ransom” project website (nomoreransom.org), a collaborative initiative by law enforcement and cybersecurity companies, for potential decryptors.
  • Essential Tools/Patches:
    • Emsisoft Decryptor for STOP/Djvu Ransomware: Download directly from Emsisoft’s official website.
    • Reputable Anti-Malware Tools: Malwarebytes, ESET, Bitdefender, etc., for removal.
    • System Restore Points/Shadow Copies: While ransomware often deletes these, it’s worth checking if they exist. Use vssadmin commands or Windows’ built-in “Previous Versions” feature.
    • Data Recovery Software: Tools like PhotoRec or Recuva might recover older, unencrypted versions of files if the ransomware deleted the originals before encrypting copies, but this is highly unlikely for modern ransomware.
  • Recommendation: The most reliable method for file recovery is restoring from uninfected backups. If you have recent backups, format the infected system, reinstall the OS, and restore your data from a clean backup. Do not pay the ransom. There is no guarantee you will receive a decryptor, and paying only funds future criminal activities.

4. Other Critical Information

  • Additional Precautions:
    • Ransom Note: The _readme.txt file is crucial. It contains the contact email ([email protected]) and sometimes a personal ID. Do not delete it until you’ve gathered all necessary information.
    • Offline vs. Online Keys: Be aware that the Emsisoft decryptor will tell you if your files were encrypted with an “online” or “offline” key. Offline key decryption is more probable, but still not guaranteed.
    • System Information: Before attempting decryption, it’s useful to collect system information (OS version, installed software) and logs, which might aid in analysis if a new decryptor becomes available.
    • Beware of Scams: Be wary of third-party “decryption services” that promise guaranteed recovery for a fee. Many are scams, and even legitimate ones often simply pay the ransom themselves, adding their own fee.
  • Broader Impact:
    • Data Loss: The most immediate and severe impact is the loss of access to critical data.
    • Operational Disruption: For organizations, ransomware can halt operations, leading to significant downtime, productivity loss, and potential revenue loss.
    • Financial Costs: Beyond the potential ransom payment (which is not recommended), there are costs associated with system remediation, data recovery, IT staff overtime, and potential legal/PR expenses.
    • Reputational Damage: For businesses, a ransomware attack can severely damage customer trust and brand reputation.
    • Psychological Toll: For individuals and small businesses, the emotional stress and feeling of violation can be significant.

This .amber variant serves as a stark reminder of the persistent threat posed by ransomware, emphasizing the critical need for robust cybersecurity hygiene and reliable backup strategies.