Antivirii 2011

Last Updated on Friday, 16 December 2011 05:26 Thursday, 15 December 2011 19:29

A suspicious file antivirii.exe has appeared in a virus analysis report. You can see it on this link

This file belongs to a rogue program named Antivirii 2011. Below are some observations about this infection.

You can use Windows/ sysinternal's autoruns or similar tool to find out suspicious files that are set to start with windows. This rogue creates several randomly named exe files in the system32 folder, only some of them can be removed which are avctivated, other files may still remain there on your computer, you may have to find them out manually. I will explain how to do that in the following paragraphs.

The installer of this virus is of about 1.01 MB. It may not be detected by antivirus programs as a virus
It creates windows registry key so that antivirii.exe runs each time windows starts
It creates several randomly named exe files in C:\windows\system32 folder. One of the files is run at the time of windows startup.
It creates a randomly named exe file at location C:\ , this file is registered as a debugger to the task manager.

Current Update
As you all may be aware by now that as soon as an article about a virus/rogue is published, the next version of the rogue appears, so you always need current information about a rogue. I will explain you an easy way to find out updated information.

Open the site http://www.threatexpert.com/reports.aspx
Use a keyword antivirii.exe to search on this site. At present this is the file that is common in all instances of this rogue. Read some of the current reports and you will find relevent information to deal with this rogue.

It creates antivirii.exe and other files on the infected computer that you need to search and delete. You should end running processes named antivirii.exe from Task Manager. And also remove the file's entries from windows startup.

Warning: It is possible that some legitimate software may be using the same file names as that of the virus files. You do not have to delete these files if they belong to some legitimate program installed on your computer. Use Windows Defender or SysInternals Process Explorer to differentiate between them. The information in this article is presented without making any claims regarding its usefulness or otherwise. If you have any objections or questions, please send a note by adding a comment at the end of this page, or mail on support(at)comprolive.com

Preventive measures

Most of the viruses enter your computer when you visit some harmful website. If you use a browser plugin that warns you about harmful websites, you can prevent this from happening. A popular browser plugin is called Web Of Trust (WOT), you can install it from its website on this link.
[ a video about WOT plugin ]
Blocking Javascript of all sites by default can help to prevent drive by download infections. You can use Noscript Plugin for firefox as explained in this video. Similar functionality can be achieved in Google's Chromium browser using the settings in Preferences > Under the Hood > Content Settings > Java Script > Select "Do not Allow". After that when you visit a site, you will see a pop up next to the address bar asking you if you want to allow JavaScript to run for that particular site.
Some of the viruses are downloaded in Internet Cache or in the Temp folder of the windows. The viruses get activated when these files are executed. You can reduce the risk of virus infection if you empty your browser cache and remove windows temp files occasionally, ideally at the end of a browsing session or before closing down your computer. Some programs like CCleaner can be set to do these things automatically. [ a video about CCleaner ]
Do not leave your computer infected and insecure. If you doubt that there could be some undetected virus on your computer, don't leave it like that. Format the hard disk and reinstall windows and all other programs. That is the sure way to clear doubts.

Using System Restore

If you know the duration since your computer is infected, you can try to restore your computer at a prior date, that will be an easy way to undo the changes done by the virus

Using system restore in windows XP
Using system restore in windows Vista
Using system restore in windows7

[ Video of How to use System Restore ]

Boot in safe mode

Sometimes you can not delete a file. You should boot in safe mode and then try to delete it.

How to boot in safe in windows XP
How to boot in safe mode in windows Vista
How to boot in safe mode in windows7

View Hidden Files

You need to enable to view hidden files and folders before searching.
How to Enable to View Hidden Files and Folders in Windows XP
How to Enable to View Hidden Files and Folders in Windows Vista
How to Enable to View Hidden Files and Folders in Windows7

[ Video of How to enable Hidden files and folders ]

Remove Processes from Task Manager

Press Ctrl Alt Del keys to open the Task Manager.Select Processes tab. You will see a list. Look for the names antivirii.exe in it. Select if found and press the End Process button. It will ask for your confirmation to end that process. Select Yes. You can end one process at a time. You can find out if a process in Task Manager is good or bad by using Windows Defender in XP and Vista. It shows the path of a process and its publisher. Harmful processes may be shown under Unknown Publisher in windows defender. Whereas in Windows7 you can find that out from the task manager itself. You can watch a video on How to use Windows Defender.

How to use Windows Defender in windows XP
How to use Windows Defender in windows Vista
How to use Windows Defender in windows7

Or you can use Sysinternal's Process Explorer. How to use Sysinternal's Process Explorer

[Video of How to use Sysinternal's/ Windows Process Explorer]

Removing entry from windows startup

The system configuration can be started in xp and in vista by typing msconfig in the run box/ start menu search box.
In xp by clicking on Start > run . The windows startup is reversible. You can check / uncheck any entry from windows startup any number of times. Watch a video on How to Use the Windows Startup

Open system configuration window.Click on the Startup tab. You will see a list all the programs that are scheduled to start with windows. Expand the middle column using your mouse pointer. That will show you the full path of the program. Locate and uncheck the boxes in front of these names "antivirii.exe" (also look for any other suspicious names)Press Apply , Press Close/Ok , Select "restart" at the next prompt.

Deleting files

1) One of the exe files is directly in the root folder, that is generally in C:\, you can browse your folders and see if there is any exe file under C:\ folder and delete it. Generally there are no legitimate exe files placed in this location.

2) The other location is the windows folder. We will look into it manually. We will take into account the fact that all the virus files have exe extension, and all virus files must have been created on the same date. Do not forget to first complete the previous step of "Enabling to view Hidden files and folders", otherwise we will not be able to search for the virus files in the windows folder. You can also uncheck the box in front of "Hide extensions of known file types", so that we are able to see the file extensions also.

Now open your C:\ folder. Locate the Windows folder, that is where we will carry out our search. Right click on the windows folder, and select search from the pop up menu. That will open the search dialog. Type *.exe (that is star dot exe) in the search box. We will be looking for all the files in the windows folder that have an extension of exe. Once the search is finished, click on View > Details, expand/ maximize the search results window so that you can see all the columns in it. Now look in the column named "Date modified", and see if the results appear latest first, if not, then you can click on the title to reverse the order. Once you have a list of all the exe files with the date of creation/modification, look for a set of names which includes the file "antivirii.exe", as we know that this is the file that is common in all the instances of this rogue, so all the other virus files that are randomly named should have been created in your computer at the same date. This way you can find out all the virus exe files in a bunch.

The next step is to note down their names, if you are unable to modify or delete them right there. You can try to rename these files by right clicking on file name/icon and selecting properties. Which will display the properties window. Here you can change the extension of the file form exe to something that you can easily remember later, for example you can rename the files as "filename.virus" or similar.

Delete the following files. Boot in safe mode or boot in the dos prompt if needed. The files below were seen in one instance of this rogue. As only one of the names is common "antivirii.exe", and all other names are randomly generated, hence those names will be different on every infected computer.

Files
C:\xhergjui.exe
C:\windows\antivirii.exe
C:\windows\erqzrrvi.exe
C:\windows\ghhbmdaq.exe
C:\windows\hffbosvb.exe
C:\windows\puffmzfk.exe

Folders
-

Files in Temp folder
%Temp%\Setup.exe

Installer File
[file and pathname of the sample #1]

(We do not know the name or the location of sample #1, it could be in your default download location or on the desktop or in a Temp folder. The files and folders in the Temp folder can be automatically removed, if you use a freeware temp files/ registry cleaner software like CCleaner)

Some Common folder locations

Virus makes create their files in uncommon locations. You can find such locations on this link.

These are the folders where you should find sub folders of legitimate programs. If you find any files (exe, dll etc) at this location, they should be treated suspiciously. The other thing to look out for is randomly named folders.

Repair Hosts File

To repair/ edit the hosts file. Login as administrator. open the following file in notepad
C:\ WINDOWS \system32 \drivers \etc \hosts
remove anything other than 127.0.0.1 Localhost, and save and close the file.

Registry Keys

There are several registry modifications done by this virus. The newly created Registry Values are:
        [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run]
            Security = "%Windir%\erqzrrvi.exe"
        so that erqzrrvi.exe runs every time Windows starts
        [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\taskmgr.exe]
            Debugger = "C:\xhergjui.exe"
        [HKEY_CURRENT_USER\Software\WinRAR SFX]
            C%%WINDOWS = "C:\WINDOWS"

You can see other registry modifications in the report from the link above

Using CCleaner

You can easily remove the files in the temp folder by running CCleaner. You can set CCleaner to run automatically each time the computer starts. Do not forget to run CCleaner > Registry menu to remove the obsolete registry entries.

If nothing works

More often a virus makes it difficult to remove its files while you are logged in windows. It may do one of the following

1) You may see the suspicious virus process running in the task manager but can not remove it.

2) Even if you delete a virus file/ or terminate the process, the process may spawn again.

3) The virus may disable system restore, registry tools, task manager, safe boot etc.

If any of these or other things done by the virus make you think/ feel that you are not able to remove the virus files then do as follows

1) Download a Knoppix Boot only CD ISO image from in your language from one of the download links from this website.

2) Burn the ISO image on a blank CD

3) Put the Knoppix Boot disk in your computer's CD drive and boot from the CD

At the beginning of boot process you will see a prompt as boot:

Type
knoppix screen=1280x1024
knoppix screen=1024x728 or any suitable resolution that your computer supports.
If you do not specify screen resolution, the knoppix will boot with minimal resolution and you may have to use command line options which is inconvenient for a windows user.

Once the knoppix window opens, click on the folder icon in the bottom left of the screen to open the PCMan file manager. It is a graphical file manager in Knoppix. It has two panels. In the left panel you should see the partitions of your hard disk. Select the partition in which windows is installed and you will instantly see all the folders. Now you can access the contents of your folders and delete suspicious files and folders just as you would do in the windows explorer.

When you are finished. Click on Log off. Now you can Turn Off or restart. Take out the knoppix CD from your drive and you can normally boot in windows.

Reprinted with permission from Threatexpert.com

Sanjay C Rajure