CERT Advisory CA-99-11 Four Vulnerabilities in the Common Desktop Environment
CERT Advisory CA-99-11 Four Vulnerabilities in the Common Desktop Environment
CERT Advisory CA-99-11 Four Vulnerabilities in the Common Desktop Environment
Original release date: September 13, 1999
Last revised: September 13, 1999
Source: CERT/CC
A complete revision history is at the end of this file.
Systems Affected
* Systems running the Common Desktop Environment (CDE)
I. Description
Multiple vulnerabilities have been identified in some distributions of
the Common Desktop Environment (CDE). These vulnerabilities are
different from those discussed in CA-98.02. We recommend that you
install appropriate vendor patches as soon as possible (see Section
III below). Until you can do so, we encourage you to disable or
uninstall vulnerable copies of the CDE package. Note that disabling
these programs will severely affect the utility of the CDE
environment.
At this time, the CERT/CC has not received any reports of these
vulnerabilities being exploited by intruders.
The ToolTalk messaging server ttsession allows independent
applications to communicate without having direct knowledge of each
other. Applications can communicate through an associated ttsession
which delivers messages via RPC calls between interested agents.
On many systems, ttsession uses AUTH_UNIX authentication (a
client-based security option) by default. When messages are received,
ttsession uses certain environment variables supplied by the client
to determine how the message is handled. Because of this, the
ttsession process can be manipulated to execute unauthorized
arbitrary programs with the privileges of the running ttsession.
Vulnerability #2: CDE dtspcd relies on file-system based authentication
The network daemon dtspcd (a CDE desktop subprocess control program)
accepts CDE requests from clients to execute commands and launch
applications remotely.
When a client makes a request, the dtspcd daemon asks the client to
create a file that has a predictable name so that the daemon can
authenticate the request. If a local user can manipulate the files
used for authentication, then that user can craft arbitrary commands
that may run as root.
Vulnerability #3: CDE dtaction buffer overflow
The dtaction utility allows applications or shell scripts that
otherwise are not connected into the CDE development environment, to
request that CDE actions be performed.
A buffer overflow can occur in some implementations of dtaction when a
username argument greater than 1024 bytes is used.
Vulnerability #4: CDE ToolTalk shared library buffer overflow in TT_SESSION
There is a vulnerability in some implementations of the ToolTalk
shared library which allows the TT_SESSION environment variable buffer
to overflow. A setuid root program using a vulnerable ToolTalk
library, such as dtsession, can be exploited to run arbitrary code as
root.
A local or remote user may be able to use this vulnerability to run
commands on a vulnerable system with the same privileges of the
attacked ttsession. For this attack to work, a ttsession must be
actively running on the system attacked. The ttsession daemon is
started whenever a user logs in using the CDE desktop, or upon
interaction with CDE at some future point.
Vulnerability #2: CDE dtspcd relies on file-system based authentication
A vulnerable dtspcd may allow a local user to run arbitrary commands
as root.
Vulnerability #3: CDE dtaction buffer overflow
A local user may be able to exploit this vulnerability to execute
arbitrary code with root privileges.
Vulnerability #4: CDE ToolTalk shared library buffer overflow in TT_SESSION
A local user may be able to exploit this vulnerability to execute
arbitrary code with root privileges.
III. Solution
Install appropriate patches from your vendor
We recommend installing vendor patches as soon as possible and disabling the
vulnerable programs until you can do so (or uninstalling the entire CDE
package if not needed). Note that disabling these programs will severely
affect the utility of the CDE environment.
Appendix A contains information provided by vendors for this advisory. We
will update the appendix as we receive more information. If you do not see
your vendor's name, the CERT/CC did not hear from that vendor. Please
contact your vendor directly.
Fujitsu's UXP/V operating system is not vulnerable to any of these
vulnerabilities.
Hewlett-Packard Company
HP-9000 Series 700/800 HP-UX releases 10.X and 11.0 systems with CDE
patches previously recommended in HP Security Bulletins are not
vulnerable to vulnerabilities #2, #3, and #4.
All HP-UX 10.X and 11.0 systems running CDE are vulnerable to
vulnerability #1.
Patches are in progress.
IBM Corporation
All releases of AIX version 4 are vulnerable to vulnerabilities #1,
#3, and #4. AIX is not vulnerable to #2. The following APARs
will be available soon:
Customers that do not require the CDE desktop functionality can
disable CDE by restricting access to the CDE daemons and
removing the dt entry from /etc/inittab. Run the following
commands as root to disable CDE:
IBM AIX APARs may be ordered using Electronic Fix Distribution
(via the FixDist program), or from the IBM Support Center. For
more information on FixDist, and to obtain fixes via the
Internet, please reference
or send electronic mail to "aixserv@austin.ibm.com" with the
word "FixDist" in the "Subject:" line. To facilitate ease of
ordering all security related APARs for each AIX release,
security fixes are periodically bundled into a cumulative APAR.
For more information on these cumulative APARs including last
update and list of individual fixes, send electronic mail to
"aixserv@austin.ibm.com" with the word "subscribe
Security_APARs" in the "Subject:" line.
Santa Cruz Operation, Inc.
SCO is investigating these vulnerabilities on SCO UnixWare 7. Other
SCO products (OpenServer 5.0.x, UnixWare 2.1.x, Open Server /
Open Desktop 3.0 and CMW+) are not vulnerable as CDE is not a
component of these releases.
SCO will make patches and status information available at
SGI acknowledges the CDE vulnerabilities reported and is currently
investigating. No further information is available at this
time. As further information becomes available, additional
advisories will be issued via the normal SGI security
information distribution methods including the wiretap mailing
list.
Until SGI has more definitive information to provide, customers
are encouraged to assume all security vulnerabilities as
exploitable and take appropriate steps according to local site
security policies and requirements.
The SGI Security Headquarters Web page is accessible at the URL
Systems running Solaris 7, 2.6, 2.5.1, 2.5, 2.4, and 2.3, and
SunOS 4.1.4 and 4.1.3_U1 are vulnerable if the UNIX
authentication mechanism (default) is used with ttsession.
The use of DES authentication is recommended to resolve this
issue. To set the authentication mechanism to DES, use the
ttsession command with the '-a' option and specify 'des' as
the argument (see ttsession(1) for more information). The use
of DES authentication also requires that the system uses Secure
NFS, NIS+, or keylogin. For more information about Secure NFS,
NIS+, or keylogin, please see the System Administration Guide,
Volume II. Information is also available at:
The CERT Coordination Center would like to thank Job de Haas for
reporting these vulnerabilities and working with the vendors to effect
fixes. We would also like to thank Network Solutions Atlantic for
their efforts in coordinating vendor solutions.
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