@aol.com

[Content by Gemini 2.5]

This document provides a comprehensive overview of the ransomware variant identified by the file extension @aol.com, which is a known variant within the prolific STOP/Djvu ransomware family.

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: The exact file extension used by this variant is .aol.com.
  • Renaming Convention: When a file is encrypted, its original name is retained, and the .aol.com extension is appended to it.
    • Example: A file named document.docx would be renamed to document.docx.aol.com. Similarly, photo.jpg would become photo.jpg.aol.com.
    • In some cases, Djvu variants might also insert a unique victim ID before the final extension (e.g., filename.txt.[unique_ID].aol.com), though for the specific .aol.com variant, the direct append is more common.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: The STOP/Djvu ransomware family, to which @aol.com belongs, first emerged in late 2017 and has been continually evolving with new variants appearing regularly. The .aol.com variant specifically was detected as part of this ongoing evolution, typically appearing in late 2019 or early 2020 as newer extensions replaced older ones in the family’s rotation. The family remains highly active, consistently releasing new extensions every few days or weeks.

3. Primary Attack Vectors

The @aol.com variant, like other STOP/Djvu ransomware, primarily relies on less sophisticated but highly effective social engineering and deceptive download tactics, rather than network exploitation.

  • Propagation Mechanisms:
    • Cracked Software/Software Bundles: This is the most prevalent vector. Users seeking pirated software (e.g., Photoshop, Microsoft Office, games, VPNs, Windows activators, keygens, patchers) from untrustworthy websites, torrent sites, or file-sharing platforms often download malicious installers or bundles that contain the ransomware.
    • Malicious Downloads/Drive-by Downloads: Visiting compromised websites or clicking on deceptive links can lead to the download of the ransomware payload without explicit user consent (drive-by download).
    • Adware Bundles: The ransomware can be bundled with seemingly legitimate freeware or shareware downloaded from third-party sites, often installed alongside unwanted adware or Potentially Unwanted Programs (PUPs).
    • Fake Updates: Prompts for fake software updates (e.g., Flash Player, Java) that, when clicked, download and execute the ransomware.
    • Phishing Campaigns (Less Common for Djvu): While not its primary method, ransomware can occasionally be delivered via malicious attachments in phishing emails, disguised as invoices, shipping notifications, or other legitimate documents.

Remediation & Recovery Strategies:

1. Prevention

  • Proactive Measures:
    • Robust Backups: Implement a 3-2-1 backup strategy: at least three copies of your data, stored on two different media, with one copy offsite or offline (e.g., external hard drive disconnected when not backing up, cloud storage).
    • Reputable Antivirus/Endpoint Protection: Use a high-quality antivirus or Endpoint Detection and Response (EDR) solution and keep it updated.
    • Software and OS Updates: Regularly update your operating system, web browsers, and all installed software to patch known vulnerabilities that attackers could exploit.
    • User Education: Train users to identify phishing attempts, suspicious links, and the dangers of downloading cracked software or files from untrusted sources.
    • Disable Unnecessary Services: Disable Remote Desktop Protocol (RDP) if not needed. If required, secure it with strong passwords, multi-factor authentication (MFA), and network-level authentication (NLA).
    • Software Restriction Policies/AppLocker: Implement policies to prevent the execution of malicious files from common ransomware drop locations (e.g., AppData, Temp folders).

2. Removal

  • Infection Cleanup:
    1. Isolate the Infected System: Immediately disconnect the infected computer from the network (unplug Ethernet cable, disable Wi-Fi) to prevent further spread to network drives or other devices.
    2. Identify and Terminate Processes: Use Task Manager (Windows) or Process Explorer to identify and terminate any suspicious processes. The ransomware often drops a ransom note named _readme.txt on the desktop and in encrypted folders.
    3. Scan and Remove: Boot the system into Safe Mode (with Networking, if needed for updates or tool downloads). Run a full scan with a reputable, updated anti-malware program (e.g., Malwarebytes, ESET, Bitdefender, Windows Defender Offline). Allow the software to remove all detected threats.
    4. Check Startup Items and Scheduled Tasks: Verify that no persistent mechanisms (like entries in msconfig startup, registry run keys, or Scheduled Tasks) have been created by the ransomware.
    5. Delete Shadow Copies: The ransomware often deletes Volume Shadow Copies (vssadmin delete shadows /all /quiet) to prevent easy restoration. If it hasn’t, manually delete them after cleaning the infection to ensure no ransomware remnants remain.
    • Important: Do NOT attempt file decryption on an actively infected system. Ensure the ransomware is completely removed first.

3. File Decryption & Recovery

  • Recovery Feasibility:
    • STOP/Djvu Decryption Tools: The feasibility of decrypting files encrypted by @aol.com depends on whether an “online” or “offline” encryption key was used.
      • Online Keys: If the victim’s computer was connected to the internet during encryption, the ransomware generates a unique “online” key for that victim, which is sent to the attacker’s server. Decryption is extremely difficult without this specific key.
      • Offline Keys: If the connection to the attacker’s server failed (e.g., no internet connection), the ransomware uses a pre-defined “offline” key. For these cases, public decryption tools are often available.
    • No More Ransom Project (STOPDecrypter/DjvuDecrypter): This is the primary resource for Djvu victims. Tools developed by security researchers (e.g., Emsisoft) are available via the No More Ransom website. These tools require an encrypted file and the ransom note (_readme.txt) to identify the ransomware variant and attempt decryption.
    • Data Recovery Software: In some instances, if shadow copies were not deleted, or if the ransomware didn’t fully overwrite the original files, data recovery software might be able to recover older, unencrypted versions of some files. This is less reliable.
    • Backups: Restoring from clean, uninfected backups remains the most reliable and recommended recovery method.
  • Essential Tools/Patches:
    • Anti-Malware Solutions: Malwarebytes, Emsisoft Anti-Malware, Bitdefender, ESET, Avast, etc.
    • STOP/Djvu Decryption Tool: Specifically, the STOPDecrypter tool available through the No More Ransom initiative. You will need to submit an encrypted file and the ransom note to their website to check if a decryption key is available.
    • Operating System Updates: Keep your Windows OS fully patched.

4. Other Critical Information

  • Additional Precautions:
    • Ransom Note: The @aol.com variant, like all Djvu variants, leaves a ransom note named _readme.txt in every folder containing encrypted files and on the desktop. This note contains instructions for contacting the attackers, typically via email (e.g., [email protected], [email protected], or [email protected], [email protected]).
    • Information Stealer: A critical characteristic of many STOP/Djvu variants (including those using .aol.com) is that they often deliver an information-stealing malware (like Vidar Stealer, Azorult, or RedLine Stealer) before the encryption process begins. This stealer attempts to exfiltrate sensitive data such as:
      • Browser history, cookies, saved passwords
      • Cryptocurrency wallet data
      • FTP client credentials
      • Desktop files
      • System information
      • Telegram chat logs
      • VPN client credentials
        This means that even if files are recovered, user credentials and other sensitive information might have been compromised, necessitating password changes for all online accounts and monitoring for fraudulent activity.
  • Broader Impact:
    • Widespread Individual and Small Business Impact: Due to its reliance on widely disseminated cracked software and deceptive downloads, Djvu ransomware frequently affects individual users and small to medium-sized businesses that might not have robust security measures in place.
    • Financial and Data Loss: Victims face potential financial losses if they pay the ransom (with no guarantee of decryption) and significant data loss if files cannot be recovered via other means.
    • Privacy Compromise: The inclusion of information stealers adds a severe layer of privacy and security risk beyond just file encryption, potentially leading to identity theft or further targeted attacks.
    • System Reinstallation: Given the high likelihood of an information stealer infection, security experts often recommend a complete reinstallation of the operating system after cleaning the ransomware to ensure all malicious components are removed and to mitigate the risk of ongoing data compromise.