Multiple vulnerabilities in Tooltalk database server

Multiple vulnerabilities in Tooltalk database server

Multiple vulnerabilities in Tooltalk database server

July 10th, 2002
CORE SECURITY TECHNOLOGIES

Date Published: 2002-07-10

Last Update: 2002-07-10

Advisory ID: CORE-20020528

Bugtraq ID: 5082, 5083

CVE Name: CVE-2002-0678, CVE-2002-0677

CERT: VU#975403, VU#299816

Title: Multiple vulnerabilities in Tooltalk database server.

Class: Implementation flaws

Remotely Exploitable: Yes

Locally Exploitable: Yes

Vendors contacted:

- Sun
CORE notification: 2002-06-10
CERT notification: 2002-06-11 4:32pm
Status:
.Vulnerable (original bug discovery on Solaris)
.Acknowledged notification on 2002-06-10
.Research in progress, no confirmation from Sun as of 2002-06-18
.Official statement forwardr by CERT: 2002-07-10

- HP
CORE notification: 2002-06-10
CERT notification: 2002-06-11
Status:
.Acknowledged notification on 2002-06-10
.Confirmed HP-UX vulnerable on 2002-06-11 and issued high priority lab fix request
.Official statement forwarded by CERT: 2002-07-10

- Compaq Computer Corporation
CORE notification: 2002-06-10
CERT notification: 2002-06-11 4:32pm
Status:
.Acknowledged notification on 2002-06-10
.Official statement forwarded by CERT: 2002-07-10

- SGI
CORE notification: 2002-06-10
CERT notification: 2002-06-11
Status:
.Acknowledged notification on 2002-06-18

- Xi Graphics (CDE for Linux)
CERT notification: 2002-06-12
Status:
.Confirmed vulnerable, fixes are available at the release date of this advisory
.Patches available : 2002-06-20

- IBM
CORE notification: 2002-06-10
CERT notification: 2002-06-11 4:32pm EST
Status:
.Confirmed vulnerable
.Official statement forwarded by CERT: 2002-07-10

- Caldera (SCO)
CERT notification: 2002-06-12 1:32pm
Status:
.Confirmed vulnerable
.Official statement forwarded by CERT: 2002-07-10

- Cray Inc.
CERT notification: 2002-06-12 1:19pm
Status:
.Acknoledged notification.
"Cray Inc. ships ToolTAlk wiht the CrayTools product but is not enabled by default
or used by any Cray provided application"

- Data General
CERT notification: 2002-06-12 1:19pm
Status:
N/A

- Fujitsu
CERT notification: 2002-06-12 1:19pm
Status:
.Acknowledged notification.
"Fujitsu's UXP/V is not vulnerable. Does not support any CDE functionalities"

- The Open Group
CERT notification: 2002-06-12 1:31pm
Status:
N/A

Release Mode: USER RELEASE


*Vulnerability Description:*

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.

Several security bugs were discovered in the rpc.ttdbserverd program that allow an attacker to:
- Overwrite 4 bytes of memory the running process with a zero (0x0L) value
- Remotely delete any file on the vulnerable host
- Locally create or overwrite any file on the vulnerable host with arbitrary contents.
- Remotely create arbitrary directory entries on the vulnerable host

These vulnerabilities by themselves can lead to remote and local compromise of the privilege root account on the vulnerable system.

Additionally these vulnerabilities may be used to build more reliable and effective exploit programs for previously published ToolTalk Database server vulnerabilities.

Exploit modules for the vulnerabilities described in this advisory are available inmediately for CORE IMPACT customers through the product support channel or as part of CORE IMPACT v1.1 or the July 2002 module update pack.


*Vulnerable Packages:*

Solaris 2.5.1 2.6 7 8 9
HP-UX 10.10 10.20 11.00 11.11
Tru64 v4.0f, v4.0g, v5.0a, v5.1, v5.1a
Xi Graphics deXtop CDE v2.1
IBM AIX 4.3.3 and 5.1.0
Caldera Open UNIX and Caldera UNIXware

Not confirmed but suspected vulnerable
- SGI IRIX 5.2-6.5.x

Not vulnerable
- Fujitsu UXP/V
- Cray Inc, CrayTools
- Caldera OpenLinux
- SCO OpenServer


*Solution/Vendor Information/Workaround*

Caldera, Inc.

Caldera Open UNIX and Caldera UnixWare provide the CDE ttdbserverd daemon, and are vulnerable to these issues. We have prepared fixes for those two operating systems, and will make them available as soon as these issues are made public.

SCO OpenServer and Caldera OpenLinux do not provide CDE, and are therefore not vulnerable.


Compaq Computer Corporation

CROSS REFERENCE: SSRT2251

At this time Compaq does have solutions in final testing and will publish HP Tru64 UNIX security bulletin (SSRT2251) with patch information as soon as testing has completed and kits are available from the support ftp web site.

A recommended workaround however is to disable rpc.ttdbserver until solutions are available. This should only create a potential problem for public software packages applications that use the RPC-based ToolTalk database server. This step should be evaluated against the risks identified, your security measures environment, and potential impact of other products that may use the ToolTalk database server.

To disable rpc.ttdbserverd:

+ Comment out the following line in /etc/inetd.conf:
rpc.ttdbserverd stream tcp swait root
/usr/dt/bin/rpc.ttdbserverd rpc.ttdbserverd
+ Force inetd to re-read the configuration file by
executing the inetd -hcommand.

Note: The internet daemon should kill the currently running rpc.ttdbserver. If not, manually kill any existing rpc.ttdbserverd process.


Cray, Inc.

Cray, Inc. does include ToolTalk within the CrayTools product. However, rpc.ttdbserverd is not turned on or used by any Cray provided application. Since a site may have turned this on for their own use, they can always remove the binary /opt/ctl/bin/rpc.ttdbserverd if they are concerned.


Fujitsu

Fujitsu's UXP/V operating system is not affected by the vulnerability reported in VU#975403 [or VU#299816] because UXP/V does not support any CDE functionalties.


Hewlett-Packard Company

HP9000 Series 700/800 running HP-UX releases 10.10, 10.20, 11.00, and 11.11 are vulnerable.

Until patches are available, install the appropriate file to replace rpc.ttdbserver.

Download rpc.ttdbserver.tar.gz from the ftp site. This file is temporary and will be deleted when patches are available from the standard HP web sites, including itrc.hp.com.

System: hprc.external.hp.com (192.170.19.51)
Login: ttdb1
Password: ttdb1
FTP Access: ftp://ttdb1:ttdb1@hprc.external.hp.com/
ftp://ttdb1:ttdb1@192.170.19.51/
File: rpc.ttdbserver.tar.gz
MD5: da1be3aaf70d0e2393bd9a03feaf4b1d

An HP security bulletin will be released with more information.


IBM Corporation

The CDE desktop product shipped with AIX is vulnerable to both the issues detailed above in the advisory. This affects AIX releases 4.3.3 and 5.1.0 An efix package will be available shortly from the IBM software ftp site. The efix packages can be downloaded from ftp.software.ibm.com/aix/efixes/security. This directory contains a README file that gives further details on the efix packages.

The following APARs will be available in the near future:
- AIX 4.3.3: IY32368
- AIX 5.1.0: IY32370


SGI

SGI acknowledges the ToolTalk vulnerabilities reported by CERT and is currently investigating. No further information is available at this time.

For the protection of all our customers, SGI does not disclose, discuss or confirm vulnerabilities until a full investigation has occurred and any necessary patch(es) or release streams are available for all vulnerable and supported IRIX operating systems. 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. As further information becomes available, additional advisories will be issued via the normal SGI security information distribution methods including the wiretap mailing list on http://www.sgi.com/support/security/.


Sun Microsystems, Inc.

The Solaris RPC-based ToolTalk database server, rpc.ttdbserverd, is vulnerable to the two vulnerabilities [VU#975403 VU#299816] described in this advisory in all currently supported versions of Solaris:

- Solaris 2.5.1, 2.6, 7, 8, and 9

Patches are being generated for all of the above releases. Sun will publish a Sun Security Bulletin and a Sun Alert for this issue. The Sun Alert will be available from:
> http://sunsolve.sun.com

The patches will be available from:
> http://sunsolve.sun.com/securitypatch

Sun Security Bulletins are available from:
> http://sunsolve.sun.com/security


The Open Group

N/A


Xi Graphics

Xi Graphics deXtop CDE v2.1 is vulnerable to this attack. A update correcting this issue will be available on our ftp site once this vulnerability has been publically announced.

When announced, the update and accompanying text file will be:

ftp://ftp.xig.com/pub/updates/dextop/2.1/DEX2100.016.tar.gz
ftp://ftp.xig.com/pub/updates/dextop/2.1/DEX2100.016.txt

Most sites do not need to use the ToolTalk server daemon. Xi Graphics Security recommends that non-essential services are never enabled. To disable the ToolTalk server on your system, edit /etc/inetd.conf and comment out, or remove, the 'rpc.ttdbserver' line. Then, either restart inetd, or reboot your machine.

Workarounds

If patches are not available from your vendor these workarounds can be implemented:

- Disable the vulnerable service
To do so, it is needed to comment out or remove the lines that refer to rpc.ttdbserverd in /etc/inetd.conf and restart the inetd daemon.

- Block connections to the vulnerable service
Block access from untrusted networks to the ToolTalk Database server program. The program is identified as RPC program number 100083 and may service requests on port 629/tcp or any other port. Use the rpcinfo program to determine on which port ttdbserver is servicing requests and block access to that port and the portmapper (111/tcp 111/udp) at the perimeter. This will not prevent exploitation from trusted networks.
In general it is advisable to block access from untrusted networks to ALL RPC services.


*Credits:*

These vulnerabilities were discovered and researched by Ricardo Quesada of the CORE IMPACT team at CORE SECURITY TECHNOLOGIES. We would like to thank CERT for their efforts coordinating the release of this advisory with CORE and the vendors.


*Technical Description - Exploit/Concept Code*

1) Overwriting portions of memory with 0L

The _TT_ISCLOSE procedure in ttdbserverd allows a client to close an open ToolTalk Database. The client needs only to perform a client call to the mentioned procedure passing a valid file descriptor as argument.

The server first checks if the authentication credentials passed in the procedure call (AUTH_UNIX) are valid for the requested operation. To do so, the server uses the file descriptor received as argument to index into a statically allocated table of structs of 24 bytes each named _tt_db_table. The table has 128 entries and each entry contains an struct with the following fields (the names given to the fields were chosen arbitrarly):

struct _tt_db_table_entry {
char * path;
int uid;
int mode;
int isopen;
int isopen2;
int aux;
};

The value in uid specifies the owner of the open database and a non zero value in the isopen field indicates that the file is open and in use.
Once the file is closed (or even if the operation fails) the _TT_ISCLOSE procedure resets the value of the isopen field to 0 to indicate that this entry in the table belongs to a file that is no longer open and in use.

A failure to perform proper range checks on the file descriptor used as index into the table allows an attacker to specify arbitrary portions of memory as table entries. By abusing this vulnerability an attacker could use the _TT_ISCLOSE procedure to overwrite portions of memory with a value of 0L. This attack is restricted to overwritting portions of memory at 24 bytes intervals (since that is the overall size of each
table entry). As we will see, the ability to do so will provide the means to perform more sophisticated attacks.


2) Deleting files remotely

The ttdbserverd program provides also a procedure to log transactions on a ToolTalk Database to a logfile. For this purpose the _TT_TRANSACTION procedure is used.

_TT_TRANSACTION receives a file descriptor and a list of records to log to the log file.
The filename for the logfile is kept in a statically allocated variable _tt_log_file.

Upon failure of a transaction operation, a generic error handler function is called and the logfile is deleted from the filesystem using the unlink() function call.

In Solaris 8 ( patch 110286-6 applied) the variable is located at:
0x0007636c 0x00000401 OBJT GLOB 0 .bss _tt_log_file

The filename for the log file is generated by concatenating the full pathname for the TT Database and the fixed string 'log_file'.

The variable is populated by the _TT_ISOPEN and _TT_TRANSACTION procedures, available to any local or remote ttdbserverd client.

A client can create a new TT database using the _TT_ISBUILD procedure call and subsequently use the _TT_TRANSACTION procedure to log transations on the newly created database to the file specified in _tt_log_file.

As described above, _TT_TRANSACTION will populate the _tt_log_file variable with the filename of the TT Database concatenated with the string 'log_file'. Therefore by creating (using _TT_ISBUILD) a TTDB named "////////etc/passwd012345689ABCDEF/file_table" and subsequently calling _TT_TRANSACTION with the valid file descriptor for that DB (received as result of the ISBUILD call) the _tt_log_file variable will end up as:

_tt_log_file = "////////etc/passwd012345689ABCDEF/log_file"

An attacker can now abuse the vulnerability described in 1) to insert a zero (and null terminate the string) leaving the _tt_log_file variable as follows:

_tt_log_file = "////////etc/passwd\0\0\0\045689ABCDEF/log_file"

Once this has been done, a call to _TT_TRANSACTION with an *invalid* file descriptor as argument (i.e. -2) will trigger the unlink in the error handler function, effectively removing the file specified in the _tt_log_file variable from the file system.

This technique can be used by an attacker to remove any file or directory on the vulnerable host.


3) Creating / Overwriting any local file

The _TT_TRANSACTION procedure follows symlinks when opening the log file in order to write the transaction log. By using a combination of the techniques described above an attacker can locally overwrite any file with any contents of her choice since the list of transaction records to log is passed by the client program.

Conclusion

This advisory describes techniques to abuse two vulnerabilities found in the CDE ttdbserver program:
- Improper checks on user suplied RPC arguments that lead to memory overwriting.
BID:5082 CERT: VU#975403 CVE:CAN-2002-0677

This is the file descriptor range check problem described in 1) and later used in 2)

- Lack of file system checks for file operations that lead to local file creation or overwriting.
This is the symlink problem described in 3)
BID:5083 CERT: VU#299816 CVE: CAN-2002-0678

The vulnerabilities and techniques described in this advisory can be abused by an attacker in order to gain privileged access to a vulnerable system both remotelly and locally, or in order to perform a denial of service attack (ie. deletion of *ANY* file remotely)

It is relevant to mention that vulnerabilities disclosed very recently (see BID:4639/CVE:NOT-ASSIGNED and BID:3382 /CVE:CAN-2001-0717) rely on the attacker's ability to make file system operations to fail in order to exploit those bugs.

Additionally, the ability to overwrite *any* portion of the process memory with a value of 0L may provide other possible attack scenarios for remote or local compromise of the vulnerable host.


*DISCLAIMER:*

The contents of this advisory are copyright (c) 2002 CORE SECURITY TECHNOLOGIES and may be distributed freely provided that no fee is charged for this distribution and proper credit is given.

$Id: ttdbserver.txt,v 1.9 2002/07/11 00:27:43 iarce Exp $