Subject: rsync 2.3.1 release - security fix (fwd)
To: None <>
From: Curt Sampson <>
List: tech-security
Date: 04/08/1999 02:50:13
This may affect us.

Curt Sampson  <>   604 801 5335   De gustibus, aut bene aut nihil.
The most widely ported operating system in the world:

---------- Forwarded message ----------
Approved-By: aleph1@UNDERGROUND.ORG
Date: Wed, 7 Apr 1999 22:21:30 +1000
From: Andrew Tridgell <>
Subject: rsync 2.3.1 release - security fix

I discovered a security hole in rsync yesterday and have released
rsync 2.3.1 to fix it.

The new version and patches against the last version are available at or

The problem happened when all of these conditions held true:

1) the source file list contains exactly one filename and that
   is the name of an empty directory
2) the source directory name is specified on the command line
   as "somedir/" or "somedir/." or "." not as "somedir"
3) the destination directory doesn't exist
4) you have recursion and permission transfer enabled (the -a option
   will do this)
5) the working directory of the receiving process is not the
   destination directory (this happens when you do remote rsync

(the short summary is that you need to be transferring an empty
directory into a non-existent directory)

In that case (which is quite rare) the permissions from the empty
directory in the source file list were set on the working directory of
the receiving process. In the case of a remote rsync over rsh or ssh
this means that the permissions on your home directory are changed to
those of the empty directory you are transferring.

This is a serious bug (and security hole) as it may change your home
directory permissions to allow other users access to your files. A
user can't exploit this hole deliberately to gain privileges (ie. this
is not an "active" security hole) but a system administrator could
easily be caught by the bug and inadvertently compromise the security
of their system.

To see if you have been hit by this bug you should look at the
permissions on your home directory. If they are not what you expect
then perhaps you have been bitten by this bug.

The fix is to chmod your home directory back to the correct
permissions and upgrade to rsync 2.3.1. The bug is in the receiving
side of rsync, so it is quite safe to continue to use older anonymous
rsync servers as long as you upgrade your client.

This bug has been present in all versions of rsync. I apologize for
any inconvenience.