----- Original Message ----- From: "Peter Gutmann" <pgut001at_private> To: <BUGTRAQat_private> Sent: Tuesday, February 29, 2000 5:55 PM Subject: Re: Disk (over)quota in Windows 2000 > Dave Tarbatt - ACS <D.A.Tarbattat_private> writes: > > >I've been looking into disk quotas under Windows 2000 and have uncovered a > >few anomalies. On top of a few peculiarities there appears to be a bug which > >allows a user to exceed their disk quota by as much as they wish. > > > >[...] > > > >I discovered by experiment that new files can be created upto a size of > >(Quota - UsedSpace + 2KB - 1byte), i.e. they can go overquota by up to 2047 > >bytes. Not too much of a problem. Extending existing files can be up to > >(Quota - UsedSpace +1KB -1byte) i.e. up to 1023 bytes overquota - nothing > >much to be worried about. > > Isn't this just a cluster-size filling issue? It looks like accounting is > being done on a bytes-used basis but files are managed on a per-cluster basis, > so it's possible to extend files out to fill the cluster without coming into > conflict with the quota system. > > Peter. > This makes it any less of a bug how? The main issue here isn't the fact that he can stretch the files up to X bytes its the fact that he can keep creating files when he's already exceeded his quota because 0 byte files still take up 1 block on the disk (512 bytes based on the NTFS system). The Win2k quota system should count each file a user creates at that minimum size even if the size is actually smaller. This will not change how the normal user works but will deny this attack and allow for more accurate accounting. Bret Piatt - bpiattat_private/dknightat_private Systems Engineer [CCNA/CCDA/MCP] PacifiCom - (530) 342-8999
This archive was generated by hypermail 2b30 : Fri Apr 13 2001 - 15:38:34 PDT