[CLOSED] USB disk drive access denied

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contrajur
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[CLOSED] USB disk drive access denied

Post by contrajur »

Access was denied on a USB hard drive, whereas before it worked on my Windows 8.1 system and my XP system for which first used and was unaffected.

Eventually after many hours and trying all sorts of things, including permissions from which I was blocked from making changes, I chanced upon what appears to be the solution but after reading the details in full below, please tell me what is going on? I did not really understand what I was doing and only tried out of desperation, as with other things earlier that failed.

First I turned off the three USB switches in Panda settings which, previously I had set on, that is USB protection, automatically vaccinate and suggest scanning when USB device inserted. Then from the control prompt as Administrator I ran

icacls t:\ /grant Administrator:(D,WDAC) t: being the letter assigned to the drive

I did not really understand what I was doing and icacls has other options, so I was very lucky. Others I had read about and tried had failed! That took a long time and afterwards everything then worked, except after switching on those Panda USB settings, access was denied again until I turned them off and ran icacls... again. That was fast this time, only making one change.

Therefore, it appears the Panda USB inoculation is the problem, but what I do not understand is this. I have a second PC, also with Windows 8.1, so I had tried the drive on that where access also had been denied.. However, after sorting that out on the PC where I use it, access is no longer denied on the other one even with the three Panda USB switches left on. I imagine, that part of the reason might be that inoculation on the first PC permanently writes a file to it, so it cannot be done again and behaves differently on the second. But why can I leave the Panda USB switches on with the second PC, but not the first? That baffles me.
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Re: USB disk drive access denied

Post by VirusBuster »

That's a strange behavior we've never been reported
We will need a PCOPInfo
We will also need to know which file system is the disk formatted on (FAT32, exFat, NTFS)
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Jorge Torre
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contrajur
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Re: USB disk drive access denied

Post by contrajur »

Any likelihood that I am right in thinking that the problem with denied access is likely to be the drive, since two PCs were affected and, by running the DOS command

icacls t:\ /grant Administrator:(D,WDAC)

on one resolved it on both? Does this DOS command icacls write to the disk drive and, as I am inclined to believe with the syntax I used, undo inoculation? Also that inoculation with Panda writes a .inf file to the drive?

Since I have resolved the matter, I am not keen to install and run PCOPinfo. That is partly because two PCs were affected and because of that I cannot see how it will give you useful information.

However, the drive concerned is a NTFS formatted Western Digital My Book 2 TB USB 3.0 drive. However, another different kind of Western Digital drive My Passport 250 GB - also NTFS - has not given any trouble and I use that all the time.

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Stephen Felce
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Re: USB disk drive access denied

Post by VirusBuster »

What this DOS command do is granting the Administrator user deletion permissions and also write the Windows DAC (Windows Data Access Components)
For more information about this tool, check iCacls
contrajur wrote:Also that inoculation with Panda writes a .inf file to the drive?
The only thing the "inoculation" or vaccination does is writing the autorun.inf file inside the USB drive without permissions so that it can't be modified
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Jorge Torre
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contrajur
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Re: USB disk drive access denied

Post by contrajur »

Just writing an autorun.inf to the disk drive appears not always to have the effect expected. Perhaps, as it does this, setting permissions so it cannot be changed is the issue. In spite of that I do not assume Panda is at fault, not least because I have no such problems with another USB disk drive.

However, having resolved the access denied issue with my USB drive with the Panda USB options switched off, turning them on again brought it back until I resolved it as before with

icacls t:\ /grant Administrator:(D,WDAC)

To my way of thinking, the more likely cause of my problem appears to be the operating system. In my experience, Windows 8.1 does appear to have quite a number of bugs in it, including sometimes access denied on a file you are trying to move or delete on another drive even after closing the application that wrote it.
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