Re: [rdiff-backup-users] Prevent rdiff-backup from deleting?
On Mon, 14 Nov 2011, Grant wrote: Because of this, I think there is a gaping security hole in any automated rdiff-backup scheme that pushes backups to the server. Pulling to the backup server eliminates this problem, but if the backup server is compromised, the infiltrator has root read access to each system being backed up and can thereby compromise each of those systems as well. Is rdiff-backup ill-suited to automated backups? This topic has been discussed here many a time. There is always a trade-off between security and ease of use. If you do push-style backups, having root access on the main system gives an attacker access to the backup system, so the backup has to be considered compromised when the main system is compromised. Depending on what purpose you keep backups for, this may not be what you want. If you do pull-style backups, and the backup system is compromised, the attacker indeed has root access to all backed up systems (possibly more than one). If you do pull-style backups and the main system is compromised, you could restore from a 'clean' increment. However, a compromised main system can go unnoticed for weeks or even months. So backups may have become compromised as well, and when keeping less history than this detection period, there would be no way to go back to a clean state after that time. Again, it all depends on the exact use of the backup tool. You could e.g. use rdiff-backup for user's files, and some other tool for system backups. All in all, this is not very specific to rdiff-backup. Other push or pull style backups have the same 'problems'. The method I prefer is having a backup server that is not reachable from the outside. Currently a box behind a NAT gateway, but could as well be a fully firewalled IP address with only outgoing traffic allowed to the hosts that are to be backed up. (Possibly even one at a time.) Any automated system can be fooled when not supervised properly ;-) -- Maarten ___ rdiff-backup-users mailing list at rdiff-backup-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/rdiff-backup-users Wiki URL: http://rdiff-backup.solutionsfirst.com.au/index.php/RdiffBackupWiki
Re: [rdiff-backup-users] Prevent rdiff-backup from deleting?
A simple solution is to edit the python source code for rdiff-backup on the backup server and restrict what it will accept for the --remove-older-than argument. You could also have two different versions of rdiff-backup on the backup server. One accessed remotely that has this option completely disabled (by editing the source). The other version would be the original code but can only be accessed from the local backup server. Sarel On 11/14/2011 9:03 PM, Grant wrote: The problem is that I run rdiff-backup in a crontab and one of the commands there includes --remove-older-than. That's a very creative solution though. Because of this, I think there is a gaping security hole in any automated rdiff-backup scheme that pushes backups to the server. Pulling to the backup server eliminates this problem, but if the backup server is compromised, the infiltrator has root read access to each system being backed up and can thereby compromise each of those systems as well. Is rdiff-backup ill-suited to automated backups? - Grantolutionsfirst.com.au/index.php/RdiffBackupWiki ___ rdiff-backup-users mailing list at rdiff-backup-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/rdiff-backup-users Wiki URL: http://rdiff-backup.solutionsfirst.com.au/index.php/RdiffBackupWiki
Re: [rdiff-backup-users] Prevent rdiff-backup from deleting?
Because of this, I think there is a gaping security hole in any automated rdiff-backup scheme that pushes backups to the server. Pulling to the backup server eliminates this problem, but if the backup server is compromised, the infiltrator has root read access to each system being backed up and can thereby compromise each of those systems as well. Is rdiff-backup ill-suited to automated backups? This topic has been discussed here many a time. There is always a trade-off between security and ease of use. If you do push-style backups, having root access on the main system gives an attacker access to the backup system, so the backup has to be considered compromised when the main system is compromised. Depending on what purpose you keep backups for, this may not be what you want. If you do pull-style backups, and the backup system is compromised, the attacker indeed has root access to all backed up systems (possibly more than one). If you do pull-style backups and the main system is compromised, you could restore from a 'clean' increment. However, a compromised main system can go unnoticed for weeks or even months. So backups may have become compromised as well, and when keeping less history than this detection period, there would be no way to go back to a clean state after that time. Again, it all depends on the exact use of the backup tool. You could e.g. use rdiff-backup for user's files, and some other tool for system backups. All in all, this is not very specific to rdiff-backup. Other push or pull style backups have the same 'problems'. The method I prefer is having a backup server that is not reachable from the outside. Currently a box behind a NAT gateway, but could as well be a fully firewalled IP address with only outgoing traffic allowed to the hosts that are to be backed up. (Possibly even one at a time.) The downside of pull-style backups is that if the backup server is compromised, the backed-up systems can be compromised easily since the infiltrator would have root read access to those systems. Your solution is to make it harder for the backup server to be compromised. That sounds pretty good, but how do you access that system remotely? - Grant Any automated system can be fooled when not supervised properly ;-) -- Maarten ___ rdiff-backup-users mailing list at rdiff-backup-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/rdiff-backup-users Wiki URL: http://rdiff-backup.solutionsfirst.com.au/index.php/RdiffBackupWiki
Re: [rdiff-backup-users] Prevent rdiff-backup from deleting?
I think (but haven't tried) you could alter the rdiff-backup option text like this (this is under Ubuntu 10.04, the location might differ with another OS): sed -i 's/remove-older-than/remove-older-thax/g' /usr/share/pyshared/rdiff_backup/*.py So unless an infiltrator knew the new command name (remove-older-thax in the example above), they couldn't use it. Dominic On 11/11/2011 20:51, Grant wrote: I'm using rdiff-backup in an automated push arrangement with access to the backup server provided via SSH keys and restricted to the rdiff-backup command like command=rdiff-backup --server. I think an infiltrator could delete a compromised machine's backups from the backup server like this: rdiff-backup --remove-older-than 1s backup@12.34.56.78::/path/to/backup Is there any way to prevent something like that from happening? - Grant ___ rdiff-backup-users mailing list at rdiff-backup-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/rdiff-backup-users Wiki URL: http://rdiff-backup.solutionsfirst.com.au/index.php/RdiffBackupWiki ___ rdiff-backup-users mailing list at rdiff-backup-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/rdiff-backup-users Wiki URL: http://rdiff-backup.solutionsfirst.com.au/index.php/RdiffBackupWiki
Re: [rdiff-backup-users] Prevent rdiff-backup from deleting?
I think (but haven't tried) you could alter the rdiff-backup option text like this (this is under Ubuntu 10.04, the location might differ with another OS): sed -i 's/remove-older-than/remove-older-thax/g' /usr/share/pyshared/rdiff_backup/*.py So unless an infiltrator knew the new command name (remove-older-thax in the example above), they couldn't use it. The problem is that I run rdiff-backup in a crontab and one of the commands there includes --remove-older-than. That's a very creative solution though. Because of this, I think there is a gaping security hole in any automated rdiff-backup scheme that pushes backups to the server. Pulling to the backup server eliminates this problem, but if the backup server is compromised, the infiltrator has root read access to each system being backed up and can thereby compromise each of those systems as well. Is rdiff-backup ill-suited to automated backups? - Grant I'm using rdiff-backup in an automated push arrangement with access to the backup server provided via SSH keys and restricted to the rdiff-backup command like command=rdiff-backup --server. I think an infiltrator could delete a compromised machine's backups from the backup server like this: rdiff-backup --remove-older-than 1s backup@12.34.56.78::/path/to/backup Is there any way to prevent something like that from happening? - Grant ___ rdiff-backup-users mailing list at rdiff-backup-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/rdiff-backup-users Wiki URL: http://rdiff-backup.solutionsfirst.com.au/index.php/RdiffBackupWiki
[rdiff-backup-users] Prevent rdiff-backup from deleting?
I'm using rdiff-backup in an automated push arrangement with access to the backup server provided via SSH keys and restricted to the rdiff-backup command like command=rdiff-backup --server. I think an infiltrator could delete a compromised machine's backups from the backup server like this: rdiff-backup --remove-older-than 1s backup@12.34.56.78::/path/to/backup Is there any way to prevent something like that from happening? - Grant ___ rdiff-backup-users mailing list at rdiff-backup-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/rdiff-backup-users Wiki URL: http://rdiff-backup.solutionsfirst.com.au/index.php/RdiffBackupWiki
