Publication Date 20/01/2017
Class TrojWare

Trojans are malicious programs that perform actions which are not authorized by the user: they delete, block, modify or copy data, and they disrupt the performance of computers or computer networks. Unlike viruses and worms, the threats that fall into this category are unable to make copies of themselves or self-replicate. Trojans are classified according to the type of action they perform on an infected computer.

Description Trojan-Downloader

Programs classified as Trojan-Downloader download and install new versions of malicious programs, including Trojans and AdWare, on victim computers. Once downloaded from the Internet, the programs are launched or included on a list of programs which will run automatically when the operating system boots up. Information about the names and locations of the programs which are downloaded are in the Trojan code, or are downloaded by the Trojan from an Internet resource (usually a web page). This type of malicious program is frequently used in the initial infection of visitors to websites which contain exploits.


JavaScript (JS) is a prototype-based programming language. JavaScript has traditionally been implemented as an interpreted language. The most common use is in web browsers, where it is used for scripting to add interactivity to web pages.


This JS script downloads and runs other malware on the victim computer. The downloaded malware is most often ransomware that encrypts user data.

Geographical distribution of attacks by the Trojan-Downloader.JS.SLoad family

Geographical distribution of attacks during the period from 20 January 2016 to 20 January 2017

Top 10 countries with most attacked users (% of total attacks)

Country % of users attacked worldwide*
1 Japan 12.67
2 Italy 8.93
3 Germany 7.96
4 USA 6.39
5 Brazil 6.00
6 Spain 4.21
7 Russian Federation 3.57
8 France 3.24
9 United Kingdom 2.80
10 Vietnam 2.28

* Percentage among all unique Kaspersky Lab users worldwide attacked by this malware