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Category: Malware

Type: Trojan-Downloader

Aliases: Kavala.[variant], Trojan-Downloader:W32/Kavala.[variant], Trojan-Downloader:JS/Kavala.[variant], Trojan:JS/Kavala.[variant], Trojan:VBS/Kavala.[variant], Trojan:W97M/Kavala.[variant]


This detection identifies a variant of the Kavala family of harmful programs, which can contact a remote server and download additional files onto the affected machine or device.


Automatic action

Based on the settings of your F-Secure security product, it will either automatically delete, quarantine or rename the detected program or file, or ask you for a desired action.

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Submit a sample

Submit a file or URL for further analysis.

Technical Details

Users typically encounter Kavala variants as files that are attached to email messages.

The contents of the email message usually follow typical social engineering patterns - for example, claiming to be a delivery invoice, business-related document or urgent legal summons - to pressure or trick users into running the attached file. Some examples of the message titles used by these emails include:

  • RE: Payment Pending
  • RE:Attachment Shipping Document
  • Tax refund due
  • Statement of Account

The files attached to the email messages are usually deceptively named. Some examples of file names used include:

  • Case_[random_number].zip
  • Refund.doc.js
  • USPS - Missed package delivery.js

Note that some Kavala files use two or more file endings, such as .doc.js; this is a common trick used by malware authors to deceive users about the nature of a file. The actual filetype will vary depending on the specific Kavala variant, and can be any of the following:

  • A Windows executable file (EXE)
  • A JavaScript file (JS)
  • A Microsoft office document file (W97M)
  • A Visual Basic Script (VBS) file

The F-Secure detection which identified the file as a Kavala variant may also indicate its filetype - for example, the detection 'Trojan:JS/Kavala.D' indicates that it is a JavaScript file.

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