Trojan.Zeroaccess.B

When Trojan.Zeroaccess.B infects a computer, it messes up the system by injecting code to Windows processes. This technique also hides the Trojan actions while inside the PC.

Trojan.Zeroaccess.B is a dangerous computer parasite that uses a very complex technique to conceal itself. This threat may also allow malware author to access the infected computer from a remote location. Its entry does not need computer user’s permission, instead, its forces the entry by taking advantage of system and software faults. Trojan.Zeroaccess.B has all means to control the infected system. It can inject codes to several processes and runs on its own on every start of Windows.

Damage Level: Medium

Systems Affected: Windows 9x, 2000, XP, Windows Vista/7

Characteristics
When Trojan.Zeroaccess.B loads on the computer, it will drop malicious files and obscure its presence while it remains inside the system. It completes this method by injecting codes on to legal Windows processes. This Trojan also creates hidden file system where it stores most of the files. To further fasten the infection, Trojan.Zeroaccess appends its code to legitimate Windows driver to avoid detection and removal.

When this Trojan is activated on 32-bit systems, it replaces several driver files under “C:\Windows\System32\Drivers\” with its own code.

While on 64-bit computers, it looks for the following folder and creates them if found nothing.
%Windir%\assembly\tmp\U
%Windir%\assembly\GAC_64
%Windir%\assembly\GAC_32
%Windir%\assembly\GAC_MSIL

Trojan.Zeroaccess.B will drop and load the following files as part of its operation.
%Windir%\assembly\tmp\{1B372133-BFFA-4dba-9CCF-5474BED6A9F6}
%System%\consrv.dll

Trojan.Zeroaccess.B constantly connects with a remote computer to download more malware and update itself. This action will improve the Trojan’s existence and performs additional malicious tasks. Allowing an unauthorized remote access is also possible through the backdoor established by the Trojan.

Distribution
This threat is spread in several ways. Most common contact with Trojan.Zeroaccess.B is through infected legitimate valid web sites. These web sites will redirect visitor’s Internet traffic to assigned web address that hosts other kind of malware, which will exploit security and software weak spot to penetrate the PC.

How to Remove Trojan.Zeroaccess.B

Step 1 : Restart Windows in SafeMode with Networking

Starting Windows is Safe Mode only loads minimal sets of files and drivers. Most start-up malware and viruses don't run in this mode because Windows only loads basic components to initiate the system.

NOTE: You will need to PRINT or BOOKMARK this procedure, as we have to restart the computer during the removal process.

To start Windows in Safe Mode with Networking, please do the following:

1. Remove all media such as floppy drive, cd, dvd, and USB devices. Then, restart the computer.

Boot in Safe Mode on Windows XP, Windows Vista, and Windows 7 system
a) Before Windows begins to load, press F8 on your keyboard.
b) It will display the Advanced Boot Options menu. Select Safe Mode.

Start computer in Safe Mode using Windows 8
a) Before Windows begins to load, press Shift and F8 on your keyboard.
b) On Recovery interface, click on 'See advanced repair options'.
c) Next, click on Troubleshoot option.
d) Then, select Advanced options from the list.
e) Lastly, please choose Windows Startup Settings and click on Restart. When Windows restarts, you will be send to a familiar Advanced Boot Options screen.
f) Select Safe Mode from the selections menu.

Safe Mode

2. Once the computer boots into Safe Mode with Networking, please proceed with the steps below.

Step 2 : Scan the Computer with TDSSKiller to Remove Trojan.Zeroaccess.B

Anti-rootkit utility called TDSSKiller is a free tool from Kasperksy that neutralizes complicated malware which effectively hides its process, folders, files and registry entries.

1. Download TDSSKiller and save the file on your desktop or any accessible spot.

Download TDSSKiller

2. Extract the contents of downloaded file (tdsskiller.zip) using archiver programs like Winzip or Winrar.
3. Locate the folder where you extracted tdsskiller.zip and double-click the file TDSSKiller.exe to launch the scanner.
4. Once TDSSKiller is open, please mark Services and drivers as well as Boot Sectors. Picking these options ensures that the program will inspect boot sector and system files that are infected with Trojan.Zeroaccess.B. Please refer to attached image.

TDSSKiller

5. Click on Start Scan button to begin scanning your system. This may take a while. You need to complete this process to make sure that the program detects and delete all components of Trojan.Zeroaccess.B.
6. When scan has finished, you may restart Windows normally. This part of the removal process using TDSSKiller is now complete.

Step 3: Run Another Scan with ZeroAccess Fix Tool

This additional step will guarantee that no more components of Trojan.Zeroaccess.B are present inside the computer. If in case the first scan fails to catch all threats, running ZeroAccess Fix Tool ensures that all remaining Trojans, viruses, and malware will be deleted.

1. Download the file FixZeroAccess.exe from the provided link. Save the file to accessible location like Windows desktop. This is a free tool created by Symantec to remove variants of Zeroaccess Trojan.

Download ZeroAccess Fix Tool

2. Close all open programs.
3. Browse for the location of the file FixZeroAccess.exe. Double-click on the file to run it. If it prompts for a security warning and ask if you want to run the file, please choose Run.
4. It will open a Zero Access Fix Tool End User License Agreement (EULA). You must accept this license agreement in order to proceed with Trojan.Zeroaccess.B removal. Please click I Accept.
5. Finally, it displays a message and prepares the computer to restart. Please click on Proceed.

Zeroaccess Fix Tool

6. When it shows a message about 'Restarting System' please click on OK button.
7. After restarting the computer, the tool will display information about identified threats. Continue running the tool by following the prompts.
8. When it reaches the final step, the tool will show the scan result containing deleted components of Trojan.Zeroaccess.B. Your computer is now free from any harm.

Ways to Prevent Trojan.Zeroaccess.B Infection

Here are some guidelines to help defend your computer from virus attack and malware activities. Being fully protected does not have to be expensive.

Install protection software to block Trojan.Zeroaccess.B and other threats

Having an effective anti-malware program is the best way to guard your computer against malware and threats. Although full version of anti-malware will cost some penny to obtain, it is still worthy to buy one. With real-time scan, it will be safer for you to browse the web, download files, and do more things online.

Get Protection Software

Keep all programs up to date

It is important to download critical update for installed programs. Software updates includes patches for security flaw that may utilize by an attacker to enter the computer. This flaw may be taken advantage by Trojan.Zeroaccess.B, viruses, and malware to attack the computer. Crucial programs to watch for updates are MS Windows, MS Office, Adobe Flash, Adobe Acrobat, and Java Runtime.

Activate security features of your Internet browser

SmartScreen Filter, Phishing and Malware Protection, and Block Attack Sites are the respective security features of Internet Explorer, Google Chrome, and Mozilla Firefox. Although, it may not fully guard your computer from online attack, at least it can lessen the risk. Enabling these features also helps to secure your private data and avoid identity theft.

Be a responsible Internet user

Antivirus programs and security features of Internet browser facilitates real-time protection and monitors harmful activities online. However, it tends to malfunction for some reasons. Thus, you do not have to be fully dependent on these tools. It is always best to practice safety measures when using the Internet.