Date: Wed, 5 May 1999 08:48:07 -0500 From: Alan McLean <amcl@flash.net> To: Warner Losh <imp@harmony.village.org> Cc: Unknown User <kernel@tdnet.com.br>, security@freebsd.org Subject: Re: Security advisories Message-ID: <19990505084807.A1046@flash.net> In-Reply-To: <199905050656.AAA08261@harmony.village.org>; from Warner Losh on Wed, May 05, 1999 at 12:56:23AM -0600 References: <372F7B24.E352AEFF@tdnet.com.br> <372E4911.3A384379@tdnet.com.br> <199905042049.OAA04590@harmony.village.org> <372F7B24.E352AEFF@tdnet.com.br> <199905050656.AAA08261@harmony.village.org>
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On Wed, May 05, 1999 at 12:56:23AM -0600, Warner Losh wrote: > In message <372F7B24.E352AEFF@tdnet.com.br> Unknow User writes: > > When a user deletes a file, the OS only removes its inode, is there any > > utils that writes 1/0 to the Hard Disk blocks ? > > Not that I'm aware of. The OS will never give those "dirty" blocks to > a user w/o first zeroing them. They are still available on the raw > device should you have good reason to expunge them from the disk. > > > And about memory, is there any utils that fill in memory with 1/0 ? > > No. Again, the OS doesn't give out dirty memory pages, so this > generally isn't a problem. The only time it might be a problem is if > a user breaks root and starts snooping in memory. However, if that > happens, the active memory can be targeted and you likely have bigger > problems to worry about. Here's an interesting paper and implementation about that http://www.cs.auckland.ac.nz/~pgut001/secure_del.html http://gsu.linux.org.tr/wipe/ -amcl To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-security" in the body of the message
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