BackSwap Trojan — How to Remove it From Infected Hosts

BackSwap Trojan — How to Remove it From Infected Hosts

This article has been created in order to explain what is the BackSwap Trojan and how to remove this malware completely from your computer.

The BackSwap Trojan is a dangerous virus that has successfully hijacked hundreds of computers. In our removal guide computer users can learn more about its mechanism of infiltration and operation, as well as the necessary steps to remove active infections from compromised hosts.

Threat Summary

TypeTrojan Horse Virus
Short DescriptionSilently infects the target machines and modifies key applications and system services.
SymptomsThe user may not experience any signs of infiltration.
Distribution MethodMalicious web links, Malicious Files, Malicious E-Mails
Detection Tool See If Your System Has Been Affected by BackSwap


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User ExperienceJoin Our Forum to Discuss BackSwap.

Grobios – How Does It Infect

The initial report of the BackSwap Trojan was reported on May 25th during a targeted attack against online banking services in Poland. According to the reports a large number of customers were impacted, specifically those from the following financial institutions:

  • PKO Bank Polski
  • Bank Zachodni WBK S.A.,
  • mBank
  • ING
  • Pekao

The hackers behind the threat were able to target transactions that range from 10 000 to 20 000 PLN which equals to amounts between 2680 to 5363 US Dollars.

The primary method of distribution is the use of SPAM email messages that use advanced social engineering tactics in order to manipulate the victims into interacting with the dangerous elements. The emails are customized to appear as notifications from the banking institutions or other commonly used companies and Internet services. They contain either a hyperlinked instance or the Trojan is directly attached to the messages. The email messages can also serve as the primary means for the distribution of infected payload carriers. Two popular variants are the following:

  • Software Installers — The hackers choose popular applications that are often installed by end users. Examples include creativity suites, system utilties, office and productivity tools and even computer games.
  • Documents — Using a similar method the targets can infect documents of different types: rich text documents, spreadsheets and presentations. Usually this is done by inserting malicious scripts (macros) that when enabled will start the infection.

It is also possible for victims to infect themselves via browser hijackers — malicious web browser plugins that are usually distributed on the relevant plugin repositories. The hackers utilize fake developer credentials and user reviews in order to manipulate the users into believing that it is a legitimate instance. The most common behavior tactics modify the default settings in order to redirect the users to a hacker-controlled site. Once this is done tracking cookies can be deployed in order to spy on the victims and afterwards the BackSwap Trojan is installed.

The malicious payloads can also be uploaded to hacker-controlled sites that are designed to look like legitimate download portals. Other popular forms include file sharing networks such as BitTorrent. It appears that the threat is being distributed using the Nemucod Downloader which is responsible for dropping the threats. Its signatures are detected with the following identifiers:

  • HEUR:Trojan.Script.Generic
  • JS.Downloader
  • JS/Dwnldr-VQJ
  • JS/TrojanDownloader.Nemucod.EAN
  • Trojan.Agent.CZBY
  • Trojan.JS.Downloader.Nemucod

Grobios – More Information and Analysis

Once the virus file is deployed to the victim hosts the infection is started. The security analysis shows that the associated malicious engine has a different mechanism of hooking to system and user-installed applications. This is done by simulating user input instead of interacting with the built-in functions. The BackSwap Trojan therefore does not need to have a specific instructions set for the different architectures.

This type of malicious threat is classified as a banking Trojan and as such interacts primarily with web browsers. Usually the most popular ones are made compatible: Mozilla Firefox, Google Chrome, Internet Explorer, Microsoft Edge, Safari and Opera. The malicious engine generates event hooks that similate actual human behavior. It is also loaded with strings that showcase potential online banking activitiy. There are several behavior events that can suggest potential banking activity: opening of bank-specific URLs, browser tabs, bookmarks, entering of two-factor authentication credentials and etc.

The browser hijacker code simulates copy and paste of keyboard output. Newer versions of it feature the possibility to interact with JavaScript code.

The security experts note that Mozilla Firefox and Google Chrome include security measures that protect against self-XSS attacks. However due to the fact that that the BackSwap Trojan simulates letter-by-letter keyboard input and copy/paste operations much of these techniques are automatically mitigated.

Whenever an active online banking session is detected the associated virus engine will hijack the transactions and modify the entered values in order to change the recipients. This happens in an automatic manner and the users have no way of controlling it.

WARNING! It is very possible that future versions of the BackSwap Trojan can exhibit new behavior strains and further adding other modules.

Remove Grobios Effectively from Windows

In order to fully get rid of this Trojan, we advise you to follow the removal instructions underneath this article. They are made so that they help you to isolate and then delete the BackSwap Trojan either manually or automatically. If manual removal represents difficulty for you, experts always advise to perform the removal automatically by running an anti-malware scan via specific software on your PC. Such anti-malware program aims to make sure that the Grobios is fully gone and your Windows OS stays safe against any future malware infections.


Martin Beltov

Martin graduated with a degree in Publishing from Sofia University. As a cyber security enthusiast he enjoys writing about the latest threats and mechanisms of intrusion.

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