Re: Write-protect sctors?

You can use the badblocks command also.

With badblocks you can check the surface from the partition in Linux and
detect defects.
        badblocks -o bad.txt /dev/
-o creates a file with the bad blocks found.
-b with the block size as its argument, only needed if fsck can not
determine the block size.
-w should not be used, it writes the disk and destroys the information,
while it verifys the write operation



On Wed, 2006-08-30 at 15:56 +0200, Andreas Ferrari wrote:
> Hi scott
> 
> Hav you checked your disk?
> You can simply do that by booting from a Knoppix CD or something similar 
> and the just dd the whole disk to /dev/null.
> If there is a read error dd wil report it and will abort, if that 
> happens its better to buy a new disk.
> 
> a simple example: dd if=/dev/xdX of=/dev/null
> Note: replace xdX wiht your disk
> 
> regards
> 
> Andreas Ferrari
> 
> scott schrieb:
> > scott wrote:
> > 
> >> Bill Church wrote:
> >>
> >>> It sounds very crazy. Did you ever actually identify if there was a 
> >>> rootkit installed? Did you try booting to a live CD of another 
> >>> distribution and investigating the disks from that live CD?
> >>>
> >>> Remember that partitioning does modify the existing data on the disk, 
> >>> just the partition table, unless you chose to do a full format that 
> >>> data is still there. However, the chances of it actually being able 
> >>> to effect anything that's not directly referencing that data by 
> >>> executing it seems improbable. I wouldn't think that simply copying a 
> >>> file over that location couldn't spawn a process, of course nothing 
> >>> is impossible.
> >>>
> >>> There is a BIOS function that is supposed to protect the boot sector, 
> >>> it's usually disabled by default on most systems. I imagine it would 
> >>> be possible for someone to modify the CMOS and protect any sectors 
> >>> they wish, but the attacker would undoubtedly need to have advanced 
> >>> knowledge of your system, BIOS, hard disk and geometry to make this 
> >>> attack possible. I highly doubt this is the case.
> >>>
> >>> It sounds like you may have a defective hard disk, I would try a disk 
> >>> diagnostic first, or maybe attempt to install another OS or 
> >>> distribution.
> >>>
> >>> -Bill
> >>>
> >>> ----- Original Message -----
> >>> From: scott Sent: Mon, 8/28/2006 11:23am
> >>> To: [email protected]
> >>> Subject: Write-protect sctors?
> >>>
> >>> I had a probable rootkit in ubuntu dapper that proved to be more 
> >>> persistent than I thought possible.I did rkhunter and showed some 
> >>> anomalies in /dev/...Trying to track those dir's down proved 
> >>> elusive,even with root enabled(in ubuntu,root is disabled by 
> >>> default.You can still sudo, but no su without certain switches,)the 
> >>> dir's effectively hid from my view.
> >>> So I decided to reinstall a clean slate.This is when I encounter 
> >>> problems that don't make sense.
> >>> As the install progresses to the partitioning of the disc,I opt for 
> >>> the erase whole disc option.It progresses to a certain point and then 
> >>> quits with an error..repeatedly.
> >>> I filed a bug report with launchpad,but my question is this:Can any 
> >>> malware you are aware of write-protect certain segments of a 
> >>> HD,without BIOS support?Or is there a BIOS trojan that I'm not aware 
> >>> of in Linux?Is this even possible with a hardened system?
> >>> Is this even possible in any system,Windows included?
> >>> What I.m asking is : Can any malware write-protect sectors on a HD 
> >>> that survive repartioning?
> >>> Sounds really crazy,huh?
> >>> Thanks,Scott
> >>>
> >> It was a problem in ubiquity, in that it never resolved to a mount 
> >> point when installing.
> >>
> >> But my point is that I eventually got the same install cd to actually 
> >> install.Now if something was trying to protect itself,only after many 
> >> attempted overwrites did I succeed,that would 
> >> seem...Almost...logical,..Maybe.!?
> >>
> >> The hard drive is fine,as far functioning,anyway.
> >>
> >> I also know that you have to have (presumably,)BIOS access to write- 
> >> protect sectors of a HD.
> >>
> >> Didn't Joanna Rutkowska demonstrate a BIOS virus,or POC,at one 
> >> time?Not likely,or probable,that this was my problem,but could it be 
> >> done....theoretically?Especially in a `nix environment?
> >>
> >> I think not.But I have been wrong so many times in my life,that I like 
> >> to think anything is possible.
> >>
> >> If ya want to do it bad enough,at least.
> >> Any other thoughts on this matter?
> >> Regards,Scott
> >>
> > Hi again.
> > I also know that BIOS is ROM,not RAM.
> > Therefore,it seems that I would have to do a BIOS flash for this to happen?
> > 
> > Regards...again,and thanks,Scott
> 
> 
-- 
Walter Lamagna
Ten Roses Buenos Aires
+54.11.4372.2250/2949
Ext.31