JS.Nemucod.[variant].Gen, Generic.JS.Nemucod[variant], Generic.JS.NemucodA.[variant], Js:trojan.downloader.nemucod.[variant], JS:Trojan.Downloader.Nemucod.[variant], Trojan.JS.Downloader.Nemucod.[variant], Trojan-Downloader:JS/Nemucod.[variant]


Trojan-Downloader.JS.Nemucod downloads and runs additional malicious files onto the system. The downloaded files are typically info-stealers, though in more recent campaigns Nemucod has also been seen delivering ransomware.


Automatic action

Based on the settings of your F-Secure security product, it will either move the file to the quarantine where it cannot spread or cause harm, or remove it.

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Technical Details

Trojan-Downloader.JS.Nemucod is distributed as a JavaScript file embedded in a ZIP file that is attached to an email message.

The emails used to deliver Nemucod are typically spam, sent out to recipients in mass mailings by the malware's distributors. The emails are usually social-engineered to appear legitimate or enticing.

Downloads malware

If an unsuspecting recipient opens the attached ZIP file and runs the JavaScript file it contains, Trojan-Downloader.JS.Nemucod will download a file to the %TEMP% folder and run it.

Nemucod is usually used by attackers to distribute malware such as Zeus variants or various password- or info-stealers. In more recent malware distribution campaigns, the file observed being downloaded by Nemucod has been ransomware, typically either TeslaCrypt or Locky.

Nemucod may also open a separate document as a decoy to mislead the user.

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