Monday, October 26, 2009

Autorun.inf Malware Threat: Protect and Remove it from your Computer and USB Drives

Autorun.inf flash drives malwares spread these days through various portable USB portable devices like iPod, external drives, pen drives.

While autorun.inf malwares are not specifically destructive to your computers, there are nasty and annoying. They cause various types of computer malfunctions, like your hard drive fails to open on double click, or double clicking on drive opens search or even your computer restarts when you try to open USB drive, infected by autorun.inf malware.

The autorun.inf virus is a common kind of virus that infects most computer systems. Tips on how to detect and remove the virus are of essence. Computer users should note that most of the times, this type of virus is spread through the mostly used removable storage devices like Memory Sticks, External HDD’s and USB drives. The spreading of this virus can be clearly illustrated in the steps it usually takes. Firstly, the virus infects the removable drive and as a following step places an autorun.inf file that contains a number of DLL files. In addition, in a few instances the autorun.inf makes a copy onto each and every partition that is on the hard disk of the user. Then, any time that the drive is plugged on a particular system, the autorun file goes on to execute itself and then copy the dlls. In actuality, it makes changes on the registry and then edits a number of startup entries. The next time a user goes to their computer; the activities of the virus will be shown when they restart their PC.

The files usually stay on the PC of the user as hidden files and the user is not in a position to enable the option of the Show Hidden File if the virus has infected the system. At the same, the virus goes on to disable other computer components as well. Such components that are likely to be disabled as well are the Registry Editor and Task Manager.

How to Protect Computer from Autorun.inf malware?

One popular way of protecting removable drives is by creating a folder or file and renaming it as AUTORUN.INF. It could enable the malware to automatically run on the system even without the users executing it. By creating this file beforehand, ideally, worms would not be able to run in this way.

However, this method is not perfect. Worms can delete the existing AUTORUN.INF file or folder, and then replace it with a malicious version. This would negate any protection placed by the user on the said file. However, by using file permissions to restrict changes, the AUTORUN.INF file can be protected more effectively.

Note: Make sure that your external drive is formatted using NTFS, as this procedure uses a specific feature of NTFS. If your removable drive is formatted using either FAT or FAT32, back up any data on the said drive first and reformat using NTFS. This may require Windows Vista or Windows 7.

  1. Create a new folder in the root directory of the removable disk and rename it as “AUTORUN.INF.”
  2. Create four more folders in the same location and named it as “recycle,” “recycler,” “recycled,” and “setup” respectively.

Note: The folders recycle, recycler, recycled and setup are optional but it is recommended for users to create these as malware often use these names/titles.

  1. Open a command prompt (cmd.exe) and go to the root directory of your removable drive.
  2. Set the folder attributes using the following DOS command:
    attrib autorun.inf /s /d –a +s +r
  3. Set the privilege level of the folder using the following DOS command:
    cacls autorun.inf /c /d administrators
  4. Select ‘Y’ and press enter when the message, “Are you sure (Y/N)?” is prompted.
  5. To test it, try to delete, modify, rename, copy, or open the created folder. If you cannot perform any of these functions, then the procedure is successful.

In addition to the above procedure, users may also choose to use hardware means of protection. Certain removable drives have an external switch that prevents the device from being written to. This would prevent malware from making any modifications to the drive, including the AUTORUN.INF file. However, as this may prove to be somewhat inconvenient, it is still a good idea to use the procedure shown above.

How to Remove Autorun.INF malware with Autorun Eater?

Autorun Eater is a tool to scan and remove suspicious ‘autorun.inf’ files found in the root directory of all drives, A-Z, in real-time. Autorun Eater will remove any suspicious ‘autorun.inf’ files even before the user attempts to open the drive.

Note: It will remove all the suspicious ‘autorun.inf‘ files from the virusinfected pen drives but will not remove any other virus files so you would have to remove them manually or with some anti-virus tools.

It also fixes the three common problems caused by the viruses (as shown in the image below).
  1. Task Manager disabled.
  2. Registry editing disabled.
  3. Hidden Folder Options.

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If you have removed all the suspicious ‘autorun.inf’ files from all your drives, you will be able to open all your drives easily including your pen drive with double click.

Note: 
Some antivirus and antispyware programs flag Autorun Eater as being infected / malware, although the application is perfectly safe and does not pose a threat to your system. This is called a 'false positive'. The term false positive is used when antivirus software wrongly classifies an innocuous (inoffensive) file as a virus. The incorrect detection may be due to heuristics or to an incorrect virus signature in a database. Similar problems can occur with antitrojan or antispyware software.


How to Remove Autorun.INF malware with Flash Disinfector?

Flash Disinfector is free autorun.inf trojans and USB/Flash disks trojans remover. The program has been designed by sUBs (author of famous utility combofix) to clean autorun.inf trojans that are running on the system.

Flash Disinfector will perform the following operations on your computer:
* Clean up the junk files spread by flash malwares.
* Delete the suspicious autorun.inf files from the root directory.
* Fix the damages done by the virus.
* Create an autorun.inf folder in root directory of your system drives.

Flash Disinfector will target the following Flash malwares (in general):

  • W32/Perlovga (copy.exe | host.exe)
  • VBS_RESULOWS.A (Hacked by Godzilla, Hacked by Moozilla)
  • Bha.dll.vbs
  • w32automa worm (Autorun.vbs)
  • Trojan.Win32.VB.atg | Win32/Dzan | Worm_vb.bnr (tel.xls.exe | mmc.exe)
  • W32/RJump.worm (RavMonE)
  • Worm.Win32.Delf.bf | W32.Fujacks (spoclsv.exe)
  • W32.Fujacks.BH (Fucker.vbs)
  • WORM_AGENT.PGV (soundmix.exe)
  • W32/Hakaglan.worm (RVHost.exe)
  • Trojan.Win32.VB.ayo [AVP] (Macromedia_Setup.exe)
  • Trojan.VBS.DeltreeY.b#1 (Destrukto!!! | destrukto.vbs)

How to use Flash Disinfector?
Download Flash Disinfector from the link below and save it to your Desktop. When Flash Disinfector has finished downloading you will now see a new icon on your desktop. Double-click Flash_Disinfector.exe icon to run it and insert your flash drive and/or other removable drives including your mobile phone and click OK button. Wait until it has finished scanning. Reboot your computer when done.

Note: Flash_Disinfector will create a hidden file named autorun.inf in each partition and every USB drive plugged in when you ran it. Don’t delete this folder. It will help protect your drives from future infection.

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