Security Market Segment LS
Wednesday, 18 October 2017 09:46

Necurs botnet now grabs telemetry data on Windows systems


The Necurs email botnet has made a return and, apart from spreading new variants of the Locky ransomware and the Trickybot trojan, also has new functionality that gathers telemetry data from the Windows desktop of its victims.

Researchers at security firm Symantec said the new functionality included the ability to take screenshots and mail them back to a remote location.

There was also an error-reporting capability that reported back any errors that were encountered by the downloader as it tried to do what it was programmed to do.


A typical invoice email sent by the Necurs botnet.

The new rash of emails from Necurs use the tried and trusted method of social engineering with a fake invoice as the lure.

If the file attached to the email was opened, then a JavaScript file was downloaded through an embedded iframe; the JavaScript, in turn, downloaded the payload that would be either Locky or Trickybot.

But that apart, the downloader also executed a PowerShell script that made a screenshot and saved it as generalpd.jpg. After this was saved, it was uploaded to a remote server.

"Much like crash reports in OSes can help software companies fix issues and build better products, these error reports can help attackers spot problems in the field and address them to improve success rates. After all, you can’t count on the victims to report back errors and issues!" researchers Eduardo Altares, Wei Wang Dai, and Mingwei Zhang wrote.


Symantec telemetry shows Necurs emails with script attachments have grown fourfold since June.

The researchers said the best way to avoid getting caught by one of these emails was to:

  • Delete any suspicious-looking emails you receive, especially if they contain links or attachments;
  • Always keep your security software up-to-date to protect yourself against any new variants of malware;
  • Keep your operating system and other software updated. Software updates will frequently include patches for newly discovered security vulnerabilities that could be exploited by attackers; and
  • Regularly back up any files stored on your computer. If your computer does become infected with ransomware, your files can be restored once the malware has been removed.

Cover graphic: courtesy Microsoft. Article-level graphics: courtesy Symantec


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Sam Varghese

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Sam Varghese has been writing for iTWire since 2006, a year after the site came into existence. For nearly a decade thereafter, he wrote mostly about free and open source software, based on his own use of this genre of software. Since May 2016, he has been writing across many areas of technology. He has been a journalist for nearly 40 years in India (Indian Express and Deccan Herald), the UAE (Khaleej Times) and Australia (Daily Commercial News (now defunct) and The Age). His personal blog is titled Irregular Expression.



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