Davfs2, lvm-user: Insecure tempfile handling

1.  Gentoo Linux Security Advisory

Version Information

Related bugreports: #68406, #69149

Synopsis

Davfs2 and the lvmcreate_initrd script (included in the lvm-user package) are both vulnerable to symlink attacks, potentially allowing a local user to overwrite arbitrary files with the rights of the user running them.

2.  Impact Information

Background

Davfs2 is a file system driver that allows you to mount a WebDAV server as a local disk drive. lvm-user is a package providing userland utilities for LVM (Logical Volume Management) 1.x features.

Description

Florian Schilhabel from the Gentoo Linux Security Audit Team found that Davfs2 insecurely created .pid files in /tmp. Furthermore, Trustix Secure Linux found that the lvmcreate_initrd script, included in the lvm-user Gentoo package, also creates temporary files in world-writeable directories with predictable names.

Impact

A local attacker could create symbolic links in the temporary files directory, pointing to a valid file somewhere on the filesystem. When Davfs2 or lvmcreate_initrd is called, this would result in the file being overwritten with the rights of the user running the software, which could be the root user.

3.  Resolution Information

Workaround

There is no known workaround at this time.

Resolution

All Davfs2 users should upgrade to the latest version:

# emerge --sync
# emerge --ask --oneshot --verbose ">=net-fs/davfs2-0.2.2-r1"

All lvm-user users should upgrade to the latest version:

# emerge --sync
# emerge --ask --oneshot --verbose ">=sys-fs/lvm-user-1.0.7-r2"

4.  References

• CAN-2004-0972