Friday, 13 December 2013

Avast! Anti-Virus Rescue Disk USB boot problems (+fixes)


If you have installed Avast! AV (Avast 2014.9.0.2008) onto your Windows system, you can make a bootable USB drive or ISO file from the Tools menu. However, you may run into problems when using it to make a USB drive. Here are some quick instructions for 3 different situations (see the 'Long Story' below for more details):

Make a bootable USB drive using the Avast utility

  1. The Flash drive MUST contain a bootable Master Boot Record and a partition table. Use RMPrepUSB and prepare the USB Flash drive first using the WinPE+FAT32+Boot as HDD options.
  2. You MUST use a 'Removable' USB Flash drive - those that appear in Windows Explorer as 'Local Disk' will not work! Use the Avast USB preparation tool to make the USB drive - ensure you get the pop-up box dialogue which warns you that the drive will be erased.

Add the Avast Rescue Disk ISO to Easy2Boot

  1. The E2B drive MUST be of the removable type (see 1.2 above).
  2. Make the ISO file using the Avast tool.
  3. Copy the ISO file to one of the level 2 folders on your E2B drive as desired (e.g. \_ISO\MAINMENU or \_ISO\ANTIVIRUS). Make sure the file is contiguous (RMPrepUSB - Ctrl+F2).
  4. Using 7Zip or similar tool, extract the \rescue folder to the USB drive (e.g. F:\rescue).

Add the Avast Rescue Disk to a grub4dos USB drive

  1. The USB drive MUST be of the removable type (see 1.2 above).
  2. Make the ISO using the Avast tool.
  3. Copy the ISO file to the desired folder (e.g. root of the USB drive). Make sure the file is contiguous.
  4. Using 7Zip or similar tool, extract the \rescue folder from the ISO file to the USB drive (e.g. F:\rescue).
  5. Use a grub4dos menu entry such as:

    title Avast! AV Rescue Disk\n Avast AV Rescue disk
    map /rescue_disc.iso (0xff)
    map --hook
    root (0xff)
    chainloader /bootmgr

Long Story

Many people are having problems making an Avast AV Rescue USB disk using the Avast USB preparation utility - see here for details.

Here are the salient points about the AV Rescue USB utility:

1. You must use a 'Removable' USB Flash drive. The Avast AV software that runs when the USB or CD boots looks for the \rescue folder on a removable drive. A removable drive can be a floppy disk (A: or B:), a CD/DVD, or a removable-type of USB Flash drive. USB Flash drives that are of the 'Fixed-disk' type (such as many modern ones with the 'Certified Windows8ToGo' icon on them) and USB HDDs will therefore not work correctly and the virus definitions will not be found after booting to WinPE.

2. You cannot test the Avast Rescue USB drive using a Virtual Machine because the VM will assign the USB drive as a 'Fixed-disk' type of drive. Therefore you must test the USB drive by booting from a real system and not a VM.

3. The Avast USB preparation utility does NOT warn you if the USB drive you have selected is of the wrong type (i.e. Fixed-disk type). It does NOT give any form of error message. You can tell if it is of the correct type if the Avast USB preparation tool warns you it is going to erase all the contents of the drive. If you don't get this warning then it will not have prepared the USB drive at all!

4. The Avast USB preparation utility does NOT re-partition the selected USB drive. If it happens to be formatted as a large floppy disk (the Windows format tool will format a blank removable USB Flash drive as a large floppy disk and so will the Disk Management tool!). So if it is unformatted or formatted as a large floppy already, you need to use a 3rd-party partitioning tool such as RMPrepUSB to partition it and format it first before you use the Avast USB utility. Windows PE (which is what the Avast Rescue OS uses) will not boot from a drive formatted as large USB floppy - you must boot from a USB drive that has a partition table.

5. The Avast USB preparation utility does NOT update the Master Boot Record of the USB drive that you select. If the MBR of the USB drive you are using does not already contain valid boot code then it won't boot. To fix this, you can use RMPrepUSB - BootLoaders - Install Std MBR (Ctrl+B) to install MBR boot code.