Published:
03 September 1998
Protect yourself against future threats.
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AUSCERT External Security Bulletin Redistribution
ESB-98.141 -- Network Associates, Inc. SECURITY ADVISORY
Stack Overflow in ToolTalk RPC Service
4 September 1998
===========================================================================
Network Associates, Inc. has released the following advisory concerning a
stack overflow in the ToolTalk RPC Service. This vulnerability may allow a
remote attacker to run arbitrary code as the superuser on hosts supporting
the ToolTalk service.
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Network Associates, Inc.
SECURITY ADVISORY
August 31, 1998
NAI Advisory 29
Stack Overflow in ToolTalk RPC Service
=======================================================================
SYNOPSIS
An implementation fault in the ToolTalk object database server allows
a remote attacker to run arbitrary code as the superuser on hosts
supporting the ToolTalk service. The affected program runs on many
popular UNIX operating systems supporting CDE and some Open Windows
installs. This vulnerability is being actively exploited by
attackers on the Internet.
=======================================================================
Confirmed Vulnerable Operating Systems and Third Party Vendors
Sun Microsystems
- ----------------
SunOS 5.6, 5.6_x86
SunOS 5.5.1, 5.5.1_x86
SunOS 5.5, 5.5_x86
SunOS 5.4, 5.4_x86
SunOS 5.3
SunOS 4.1.
SunOS 4.1.3_U1
Hewlett Packard
- ---------------
HP-UX release 10.10
HP-UX release 10.20
HP-UX release 10.30
HP-UX release 11.00
SGI
- ---
IRIX 5.3
IRIX 5.4
IRIX 6.2
IRIX 6.3
IRIX 6.4
IBM
- ---
AIX 4.1.X
AIX 4.2.X
AIX 4.3.X
TriTeal
- -------
TriTeal CDE - TED versions 4.3 and previous.
Xi Graphics
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Xi Graphics Maximum CDE v1.2.3
It should be noted here that this not an exhaustive list of vulnerable
vendors. These are only the *confirmed vulnerable* vendors. Also, any
OS installation that is not configured to use or start up the ToolTalk
service is not vulnerable to this problem.
To determine whether the ToolTalk database server is running on a
host, use the "rpcinfo" command to print a list of the RPC services
running on it, as:
$ rpcinfo -p <hostname>
Because many operating systems do not include an entry for the
ToolTalk
database service in the RPC mapping table ("/etc/rpc" on most Unix
platforms), the vulnerable service may not appear by name in the
listing.
The RPC program number for the ToolTalk database service is 100083. If
an entry exists for this program, such as,
100083 1 tcp 692
then the service is running on the host. Until additional information
is made available from the OS vendor, it should be assumed that the
system is vulnerable to the attack described in this advisory.
========================================================================
DETAILS
The ToolTalk service allows independently developed applications
to communicate with each other by exchanging ToolTalk messages.
Using ToolTalk, applications can create open protocols which allow
different programs to be interchanged, and new programs to be
plugged into the system with minimal reconfiguration.
The ToolTalk database server (rpc.ttdbserverd) is an ONC RPC service
which manages objects needed for the operation of the ToolTalk
service.
ToolTalk-enabled processes communicate with each other using RPC calls
to this program, which runs on each ToolTalk-enabled host. This
program
is a standard component of the ToolTalk system, which ships as a
standard component of many commercial Unix operating systems. The
ToolTalk database server runs as root.
Due to an implementation fault in rpc.ttdbserverd, it is possible for
a malicious remote client to formulate an RPC message that will cause
the server to overflow an automatic variable on the stack. By
overwriting activation records stored on the stack, it is possible to
force a transfer of control into arbitrary instructions provided by
the attacker in the RPC message, and thus gain total control of the
server process.
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TECHNICAL DETAILS
Source code and XDR specifications for the ToolTalk database protocol
and server were not available at the time this advisory was drafted.
What follows is information based on analysis of the rpc.ttdbserverd
binary and a captured attack trace from a network on which an
exploitation script for this problem was run.
The observed attack utilized the ToolTalk Database (TTDB) RPC
procedure number 7, with an XDR-encoded string as its sole argument.
TTDB procedure 7 corresponds to the _tt_iserase_1() function symbol
in the Solaris binary (/usr/openwin/bin/rpc.ttdbserverd). This
function implements an RPC procedure which takes an ASCII string as
an argument, which is treated as a pathname.
The pathname string is passed to the function isopen(), which in
turn passes it to _am_open(), then to _amopen(), _openfcb(),
_isfcb_open(), and finally to _open_datfile(), where it, as the first
argument to the function, is passed directly to a strcpy() to a
pointer on the stack. If the pathname string is suitably large, the
string overflows the stack buffer and overwrites an activation record,
allowing control to transfer into instructions stored in the pathname
string.
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RESOLUTION
This is an implementation problem and can only be resolved completely
by applying patches to or replacing affected software. As a temporary
workaround, it is possible to eliminate vulnerability to this problem
by disabling the ToolTalk database service. This can be done by
killing
the "rpc.ttdbserverd" process and removing it from any OS startup
scripts. It should be noted that this may impair system functionality.
The following vendors have been confirmed vulnerable, contacted, and
have responded with repair information:
Sun Microsystems
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Sun plans to release patches this week that relate to the ToolTalk
vulnerability for SunOS 5.6, 5.6_x86, 5.5.1, 5.5.1_x86, 5.5 and
5.5_x86.
Patches for SunOS 5.4, 5.4_x86, 5.3, 4.1.4 and 4.1.3_U1 will be
released
in about 4 weeks.
Sun recommended and security patches (including checksums) are
available from:
http://sunsolve.sun.com/sunsolve/pubpatches/patches.html
Hewlett Packard
- ---------------
HP-UX has been confirmed vulnerable in releases 10.XX and 11.00. HP
has made patches available with the following identifications:
HP-UX release 10.10 HP9000 Series 7/800 PHSS_16150
HP-UX release 10.20 HP9000 Series 7/800 PHSS_16147
HP-UX release 10.30 HP9000 Series 7/800 PHSS_16151
HP-UX release 11.00 HP9000 Series 7/800 PHSS_16148
IBM
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IBM AIX has been confirmed vulnerable. IBM's response is as follows:
The version of ttdbserver shipped with AIX is vulnerable. We are
currently working on the following fixes which will be available soon:
APAR 4.1.x: IX81440
APAR 4.2.x: IX81441
APAR 4.3.x: IX81442
Until the official APARs are available, a temporary fix can be
downloaded via anonymous ftp from:
ftp://aix.software.ibm.com/aix/efixes/security/ttdbserver.tar.Z
TriTeal
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An official response from TriTeal is as follows:
The ToolTalk vulnerability will be fixed in the TED4.4 release. For
earlier versions of TED, please contact the TriTeal technical support
department at <support@triteal.com> or at
http://www.triteal.com/support.
Xi Graphics
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An official response from Xi Graphics is as follows:
Xi Graphics Maximum CDE v1.2.3 is vulnerable to this attack. A patch
to correct this problem will be placed on our FTP site by 8/28/1998:
ftp.xig.com:/pub/updates/cde/1.2.3/C1203.002.tar.gz
ftp.xig.com:/pub/updates/cde/1.2.3/C1203.002.txt
Users of Maximum CDE v1.2.3 are urged to install this update.
Silicon Graphics
- ----------------
The Security Labs team at Network Associates has confirmed that SGI
IRIX 6.3 is vulnerable to this attack. SGI's security team has been
contacted and informed of the vulnerability. No repair information
has been made available from Silicon Graphics regarding this problem.
Other Vendors
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If any uncertainty exists with regards to whether a given vendor not
listed in this advisory is vulnerable to this attack, we recommend
contacting them via their support/security channels for more
information.
========================================================================
ACKNOWLEDGEMENTS
The NAI Security Labs Team would like to thank the HP & IBM Security
Response
Teams, CERT/CC & AUSCERT for their contributions to this advisory.
=======================================================================
ABOUT THE NETWORK ASSOCIATES SECURITY LABS
The Security Labs at Network Associates hosts some of the most
important
research in computer security today. With over 28 published security
advisories published in the last 2 years, the Network Associates
security
auditing teams have been responsible for the discovery of many of the
Internet's most serious security flaws. This advisory represents our
ongoing commitment to provide critical information to the security
community.
For more information about the Security Labs at Network Associates,
see our website at http://www.nai.com or contact us at
<seclabs@nai.com>.
=======================================================================
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