============================================================================ rsnapshot Security Advisory 001 security@xxxxxxxxxxxxx http://www.rsnapshot.org/security/ Apr 10th, 2005 Nathan Rosenquist ============================================================================ Severity: high Vulnerability: local privilege escalation Fix provided: yes ------------- 1) Background ------------- rsnapshot is a filesystem snapshot utility for making backups of local and remote systems. Using rsync and hard links, it is possible to keep multiple, full backups instantly available. The disk space required is just a little more than the space of one full backup, plus incrementals. ---------------------- 2) Problem description ---------------------- The copy_symlink() subroutine in rsnapshot incorrectly changes file ownership on the files pointed to by symlinks, not on the symlinks themselves. This would allow, under certain circumstances, an arbitrary user to take ownership of a file on the main filesystem. This subroutine is called under the following circumstances: a) If the cmd_cp parameter has NOT been enabled, OR b) If the backup_script parameter is set, and the backup script generates symlinks as part of its output c) AND if the attacker can create symlinks in a directory that is backed up, either by creating them directly or influencing a backup script. This vulnerability has been fixed in rsnapshot versions 1.1.7 and 1.2.1. It is recommended that all users upgrade immediately. ----------------------- 3) Upgrade Instructions ----------------------- For users of rsnapshot 1.2.0, download and install version 1.2.1. For users of rsnapshot 1.1.6 or earlier, download and install version 1.1.7. --------------- rsnapshot 1.2.1 --------------- http://www.rsnapshot.org/downloads/rsnapshot-1.2.1.tar.gz http://www.rsnapshot.org/downloads/rsnapshot-1.2.1.tar.gz.asc http://www.rsnapshot.org/downloads/rsnapshot-1.2.1-1.noarch.rpm http://www.rsnapshot.org/downloads/rsnapshot-1.2.1-1.noarch.rpm.asc http://www.rsnapshot.org/downloads/rsnapshot_1.2.1-1_all.deb http://www.rsnapshot.org/downloads/rsnapshot_1.2.1-1_all.deb.asc --------------- rsnapshot 1.1.7 --------------- http://www.rsnapshot.org/downloads/rsnapshot-1.1.7.tar.gz http://www.rsnapshot.org/downloads/rsnapshot-1.1.7.tar.gz.asc http://www.rsnapshot.org/downloads/rsnapshot-1.1.7-1.noarch.rpm http://www.rsnapshot.org/downloads/rsnapshot-1.1.7-1.noarch.rpm.asc http://www.rsnapshot.org/downloads/rsnapshot_1.1.7-1_all.deb http://www.rsnapshot.org/downloads/rsnapshot_1.1.7-1_all.deb.asc -------------- 4) Workarounds -------------- Enable the cmd_cp parameter (requires GNU cp, and works best on Linux). Make sure any scripts specified by the backup_script parameter do not create symlinks.
