Trojan-Downloader:​JS/Advedo

Summary

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This type of trojan secretly downloads malicious files from a remote server, then installs and executes the files.

Removal

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Automatic action

Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.

More

Detailed instructions for F-Secure security products are available in the documentation found in the Downloads section of our Home - Global site.

You may also refer to the Knowledge Base on the F-Secure Community site for further assistance.

Technical Details

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Trojan-Downloader:JS/Advedo is part of a multi-stage malware that is injected into legitimate websites. When a visitor arrives at the compromised website, the malware uses several scripts to force a file download onto the visitor's computer.

The various scripts used are written in JScript and VBS.

Activity

The first part of this script Trojan is injected into a legitimate website and placed after the website's closing HTML tag. This script allows the execution of another script from the following predetermined website:

• https://qzh.txshi.com/

The second part of the malware inserts an iframe into the website. The site inserted is still contained from the same domain.

The third part of the malware (a combination of JScript and VBS) downloads a file from the following website:

• https://qzh1.txshi.com/

At the time of analysis, the downloaded file is no longer available.

If the download is successful, the file is saved into the temporary folder of the system as:

• nettool.exe

The file ~net.bat is then created in the temporary folder and is used to execute the downloaded file.