How to remove the Backdoor.TeamViewer Trojan

  • June 7, 2016

Backdoor.Teamviewer is a Trojan that pretends to be an Adobe Flash Player installer, but in reality installs a copy of the TeamViewer remote access software on to the victim's computer. Once TeamViewer is installed, it will connect back to the attackers Command & Control server and submit the IP address of the infected computer as shown below.

  • Command & Control Server Communication

Once the attackers have the victim's IP address, they are able to connect remotely to the victim's computer and take remote control of it. While connected they will be able to use the computer as if they were in front of it. This allows them to view your documents, pictures, and run other programs that steal passwords to your online accounts.

Unfortunately, the only clues that would indicate you are infected with this Trojan is if you notice the %AppData%\Sin\5s.exe application running on your computer or if they take control of it while you are watching. Therefore, it is important to make sure your computer is running a good antivirus program with updated security definitions.

It has been thought that this malware may be one of the vectors for the many TeamViewer hacks that have been reported in May & June of 2016. This Trojan is currently being detected as Trojan.Teamspy, Gen:Variant.Mikey, Win32.Trojan-spy.Teamspy, Trojan-Spy.Win32.Teamspy, and Backdoor.TeamViewer by various antivirus programs.

How did the Backdoor.Teamviewer get on my computer?

The Backdoor.Teamviewer Trojan is distributed as an Adobe Flash installer. When visiting certain sites or trying to access content, a message will appear stating that your Adobe Flash is outdated or that you need to install a new version to access the content on the page. When you download the installer, it will actually install the legitimate Flash on to your computer, but at the same time will install the Backdoor.Trojan as well in the background without your knowledge.

If you believe you are infected with the Backdoor.TeamViewer application you can use the removal guide below to check for it's existence and remove it.

Self Help Guide

This guide contains advanced information, but has been written in such a way so that anyone can follow it. Please ensure your data is backed up before proceeding.

If you are uncomfortable making changes to your computer or following these steps, do not worry! Instead you can get free one-on-one help by asking in the forums.

To remove Backdoor.TeamViewer, follow these steps:

1

This removal guide may appear overwhelming due to the amount of the steps and numerous programs that will be used. It was only written this way to provide clear, detailed, and easy to understand instructions that anyone can use to remove this infection for free. Before using this guide, we suggest that you read it once and download all necessary tools to your desktop. After doing so, please print this page as you may need to close your browser window or reboot your computer.

2

Reboot your computer into Safe Mode with Networking using the instructions for your version of Windows found in the following tutorial:

How to start Windows in Safe Mode

When following the steps in the above tutorial, select Safe Mode with Networking rather than just Safe Mode. When the computer reboots into Safe Mode with Networking make sure you login with the username you normally use. When you are at your Windows desktop, please continue with the rest of the steps.

3

To terminate any programs that may interfere with the removal process we must first download the Rkill program. Rkill will search your computer for active malware infections and attempt to terminate them so that they wont interfere with the removal process. To do this, please download RKill to your desktop from the following link.

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Rkill

When at the download page, click on the Download Now button labeled iExplore.exe. When you are prompted where to save it, please save it on your desktop.

4

Once it is downloaded, double-click on the iExplore.exe icon in order to automatically attempt to stop any processes associated with Backdoor.TeamViewer and other malware. Please be patient while the program looks for various malware programs and ends them. When it has finished, the black window will automatically close and a log file will open. Please review the log file and then close so you can continue with the next step. If you have problems running RKill, you can download the other renamed versions of RKill from the rkill download page. All of the files are renamed copies of RKill, which you can try instead. Please note that the download page will open in a new browser window or tab.

Do not reboot your computer after running RKill as the malware programs will start again.

5

Now that you are in safe mode, the Backdoor.TeamViewer Trojan will not be active and we can delete it. To do this, we need to first open the folder the files are stored in.

To open the folder, click on the Windows key (), and while holding it down, click on the R key on your keyboard. When the Run dialog appears, type %AppData% and press Enter on your keyboard

6

The %AppData% folder should now be open and you will be shown a list of folders. Scroll down until you find the Sin folder. Once you find the folder, right-click on it and select Delete as shown below.

Delete Sin Folder

7

Once you have deleted the Sin folder, and only the Sin folder, you can right-click on your Recycle Bin and select Empty to permanently delete it.

8

If your computer is still in Safe Mode with Networking, you can reboot your computer back to normal mode. Once your computer is rebooted and you are back at the desktop, you can proceed with the rest of the instructions.

9

Now please download Emsisoft Anti-Malware, which will scan for and remove any other adware that may have been bundled with this adware. Please download and save the Emsisoft Anti-Malware setup program to your desktop from the link below:

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Emsisoft Anti-Malware

The download is fairly large, so please be patient while it downloads.

10

Once the file has been downloaded, double-click on the EmsisoftAntiMalwareSetup_bc.exe icon to start the program. If Windows Smart Screen issues an alert, please allow it to run anyway.

If the setup program displays an alert about safe mode, please click on the Yes button to continue. You should now see a dialog asking you to agree to a license agreement. Please access the agreement and click on the Install button to continue with the installation.

11

You will eventually get to a screen asking what type of license you wish to use with Emsisoft Anti-Malware.

Select License Screen

If you have an existing license key or want to buy a new license key, please select the appropriate option. Otherwise, select the Freeware or Test for 30 days, free option. If you receive an alert after clicking this button that your trial has expired, just click on the Yes button to enter freeware mode, which still allows the cleaning of infections.

12

You will now be at a screen asking if you wish to join Emsisoft's Anti-Malware network. Read the descriptions and select your choice to continue.

13

Emsisoft Anti-Malware will now begin to update it's virus detections.

Downloading Updates

Please be patient as it may take a few minutes for the updates to finish downloading.

14

When the updates are completed, you will be at a screen asking if you wish to enable PUPs detection. We strongly suggest that you select Enable PUPs Detection to protect your computer from nuisance programs such as toolbars and adware.

15

You will now be at the final installation screen. Please click on the Finish Installation button end the setup and automatically launch Emsisoft Anti-Malware.

16

Emsisoft Anti-Malware will now start and display the start screen.

Emsisoft Anti-Malware Start Screen

At this screen, please left-click on the Scan section.

17

You will now be at a screen asking what type of scan you would like to perform.

Scan selection screen

Please select the Malware Scan option to begin scanning your computer for infections. The Malware Scan option will take longer than the Quick Scan, but will also be the most thorough. As you are here to clean infections, it is worth the wait to make sure your computer is properly scanned.

18

Emsisoft Anti-Malware will now start to scan your computer for rootkits and malware. Please note that the detected infections in the image below may be different than what this guide is for.

Scanning screen

Please be patient while Emsisoft Anti-Malware scans your computer.

19

When the scan has finished, the program will display the scan results that shows what infections where found. Please note, due to an updated version of Emsisoft Anti-Malware, the screenshot below may look different than the rest of the guide.

Scan Results

Now click on the Quarantine Selected button, which will remove the infections and place them in the program's quarantine. You will now be at the last screen of the Emsisoft Anti-Malware setup program, which you can close. If Emsisoft prompts you to reboot your computer to finish the clean up process, please allow it to do so. Otherwise you can close the program.

20

Now you should download HitmanPro from the following location and save it to your desktop:

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HitmanPro

When you visit the above page, please download the version that corresponds to the bit-type of the Windows version you are using.

21

Once downloaded, double-click on the file named HitmanPro.exe (for 32-bit versions of Windows) or HitmanPro_x64.exe (for 64-bit versions of Windows). When the program starts you will be presented with the start screen as shown below.

HitmanPro Start Screen

Now click on the Next button to continue with the scan process.

22

You will now be at the HitmanPro setup screen. If you would like to install the 30 day trial for HitmanPro, select the Yes, create a copy of HitmanPro so I can regularly scan this computer (recommended) option. Otherwise, if you just want to scan the computer this one time, please select the No, I only want to perform a one-time scan to check this computer option.

Kickstart Setup Options

Once you have selected one of the options, please click on the Next button.

23

HitmanPro will now begin to scan your computer for infections, adware, and potentially unwanted programs. When it has finished it will display a list of all the items that Hitman has found as shown in the image below. Please note that the items found may be different than what is shown in the image.

MalwareBytes Scan Results

You should now click on the Next button to have HitmanPro remove the detected items. When it is done you will be shown a Removal Results screen that shows the status of the various programs that were removed. At this screen you should click on the Next button and then if prompted you should click on the Reboot button. If HitmanPro does not prompt you to reboot, please just click on the Close button.

Once your computer has has restarted or you pressed the Close button, you should now be at your Windows desktop.

24

As many malware and unwanted programs are installed through vulnerabilities found in out-dated and insecure programs, it is strongly suggested that you use Secunia PSI to scan for vulnerable programs on your computer. A tutorial on how to use Secunia PSI to scan for vulnerable programs can be found here:

How to detect vulnerable and out-dated programs using Secunia Personal Software Inspector

Your computer should now be free of the Backdoor.TeamViewer program. If your current security solution allowed this program on your computer, you may want to consider purchasing the full-featured version of Emsisoft Anti-Malware to protect against these types of threats in the future.

If you are still having problems with your computer after completing these instructions, then please follow the steps outlined in the topic linked below:

Preparation Guide For Use Before Using Malware Removal Tools and Requesting Help

Are Your Protected?

While Emsisoft Anti-Malware & HitmanPro will scan and clean a computer for free, the free versions do not offer real-time protection. If you want to be fully protected at all times then it is recommended that you purchase a premium version.

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Emsisoft Anti-Malware

Purchase the full-featured version of Emsisoft Anti-Malware, which includes real-time protection and behavior blocker, to protect yourself against these types of threats in the future!


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HitmanPro

Purchase the full-featured version of HitmanPro, which includes discover viruses, trojans, rootkits, spyware and other malware on up-to-date and fully protected computers using cloud protection and behavioral detections, to protect yourself against these types of threats in the future!

Disclaimer: While we do earn a commission from the sale of the above products, rest assured we only recommend them due to their effectiveness.

View Associated Backdoor.TeamViewer Files

%AppData%\Sin\ %AppData%\Sin\5s.exe %AppData%\Sin\avicap32.dll %AppData%\Sin\nv8moxflu

File Location Notes:

%AppData% refers to the current users Application Data folder. By default, this is C:\Documents and Settings\<Current User>\Application Data for Windows 2000/XP. For Windows Vista and Windows 7 it is C:\Users\<Current User>\AppData\Roaming.

View Associated Backdoor.TeamViewer Registry Information

HKCU\Software\Microsoft\Windows\CurrentVersion\Run\5s %AppData%\Sin\5s.exe

This is a self-help guide. Use at your own risk.

BleepingComputer.com can not be held responsible for problems that may occur by using this information. If you would like help with any of these fixes, you can ask for malware removal assistance in our Virus,Trojan,Spyware, and Malware Removal Logs forum.

If you have any questions about this self-help guide then please post those questions in our Am I infected? What do I do? and someone will help you.

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