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  • Writer's pictureSecneurX Threat Analysis

What is SkullLocker Ransomware ?

SecneurX Analysts found the SkullLocker Ransomware in the wild and analyzed the sample. This ransomware exhibits several similarities and overlaps with Chaos Ransomware. Chaos is a customizable ransomware builder that emerged in underground forums, by falsely marketing itself as the .NET version of Ryuk despite sharing no such overlaps with the notorious counterpart. The fact that it’s offered for sale also means that any malicious actor can purchase the builder and develop their own ransomware strains, turning it into a potent threat. SkullLocker Ransomware encrypts files and appends its extension (".skull") to filenames. Also, it drops the "Read_it.txt" file that contains a ransom note. After executing the SkullLocker ransomware all files and folders gets encrypted and appended their filenames with a ".skull" extension. For Example, a file titled "Sep2019.docx" appears as "Sep2019.docx.skull", "Jan2020.docx" as "Jan2020.docx.skull", and so on. "Use the IoCs outlined in this report to monitor for a Chaos infection, as well as connections to any suspicious infrastructure," the analysts recommended. Screenshot of files encrypted by SkullLocker Ransomware

SkullLocker Ransomware Overview

Encrypt ransomware notes inform victims that their files have been encrypted. It instructs victims to buy decryption software that will able to recover all files and folders that were encrypted. The victim has to pay $1500 for the software and the payment should be made in bitcoin and also an email address ("") mentioned in the Ransomware note.

How does ransomware infect my computer?

Malware (ransomware included) is spread using phishing and social engineering tactics. Malicious programs are typically presented as or bundled with ordinary content. Infectious files can be executables (.exe, .run, etc.), archives (ZIP, RAR, etc.), Microsoft Office and PDF documents, JavaScript, and so on. When a virulent file is executed, run, or otherwise opened - the infection process is jumpstarted.

Screenshots of SkullLocker Ransomware Text file (“read_it.txt")

Translated ( "read_it.txt") in Text



Your files have been encrypted by SkullLocker ransomware. To regain access to them, you must pay the ransom within 72 hours. Otherwise, the data will be permanently lost.

For more information on how to pay the ransom and recover your files, go to the website given below.


If you have any questions, you can contact us using the email address [email address].

Do not try to remove ransomware or try to recover data with antivirus software. This may permanently damage your files.

Remember that time is of the essence. The longer you wait, the less chance you have of recovering your files.

Best regards,

Ransomware team





What can you do to avoid being a ransomware victim?

As dangerous as ransomware is, simply being aware and staying updated with the latest ransomware trends can go a long way in securing your data and systems. Here are helpful tips on how you can defend yourself from a likely attack.

Scrutinize emails & their attachments before opening them

Be wary of emails from unverified sources. You can check by communicating directly with the purported sender to confirm if they sent the messages. To check its validity, you can use SecneurX Sandbox to verify the sanity of the email.

Avoid clicking embedded links found in unverified emails

Such social engineering tricks can lead to the download of ransomware. Additionally, be wary of sites that prompt you to enter a CAPTCHA code as this could be linked to a ransomware attack. To check its validity, you can use services like SecneurX Sandbox to verify the reputation of the site.

Back up your important files

While prevention is always better than the cure, having a backup of important files can at least lessen the potential damage done by a ransomware attack. While being locked out of your own system is always a bad thing, at least it's not a total disaster since you can always retrieve your important files. The 3-2-1 backup rule applies here—three backup copies of your data on two different media and one of those copies in a separate location.

Regularly update software, programs, and applications

Updating them to the latest versions can provide an added layer of protection against online threats as some ransomware arrives via vulnerability exploits.

Use a layered protection suite

Doing so can detect threats before they enter your network. Security solutions like SecneurX ATP can block Infectious files (like executables (.exe, .run, etc.), archives (ZIP, RAR, etc.), Microsoft Office and PDF documents, JavaScript, and so on) by scanning them at the point of entry of the organizations (File uploads, USB file transfers, etc.

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