CERT^® Advisory CA-1990-12 SunOS TIOCCONS Vulnerability

A complete revision history is at the end of this file.

The following information was sent to us from Sun Microsystems. It contains availability information regarding a fix for a vulnerability in SunOS 4.1 and SunOS 4.1.1. (A version for SunOS 4.0.3 is currently in testing and should be available shortly.) For more information, please contact Sun Microsystems at 1-800-USA-4SUN.

Sun Microsystems Security Bulletin

Sun expressly disclaims all liability for any misuse of this information by any third party.

These patches are available through your local Sun answer centers worldwide. As well as through anonymous ftp to ftp.uu.net:~ftp/sun-dist

sum of SunOS 4.1 tarfile 100187-01.tar.Z  : 14138   142
sum of SunOS 4.1.1 tarfile 100188-01.tar.Z: 24122   111

README information follows:

SunOS release: 4.1.1

Unbundled Product:

Unbundled Release:

Topic:

BugId's fixed with this patch: 1008324

Architectures for which this patch is available: sun3 sun3x sun4 sun4c

Patches which may conflict with this patch:

Obsoleted by: Next major release of SunOS

Problem Description: TIOCCONS can be used to re-direct console output/input away from "console"

Patch contains kernel object modules for:

/sys/sun?/OBJ/cons.o
/sys/sun?/OBJ/zs_async.o
/sys/sun?/OBJ/mcp_async.o
/sys/sun?/OBJ/mti.o

NOTE: The sun4c does not use mti.o nor mcp_async.o since this architecture does not have VME slots and therefore cannot use the ALM-2 Asynchronous Line Multiplexor or Systech MTI-800/1600. So those modules are not needed.

The fix consists of adding permission checking to setcons, the routine that does the work of console redirection, and changing its callers to supply additional information required for the check and to see whether or not the check succeeded. Setcons now uses uid and gid information supplied to it as new arguments to perform a VOP_ACCESS call for VREAD permission on the console. If the caller doesn't have permission to read from the console, setcons rejects the redirection attempt.

Install

As Root:

# mv /sys/sun?/OBJ/cons.o /sys/sun?/OBJ/cons.o.orig
# mv /sys/sun?/OBJ/tty_pty.o /sys/sun?/OBJ/tty_pty.o.orig
# mv /sys/sun?/OBJ/zs_async.o /sys/sun?/OBJ/zs_async.o.orig
# mv /sys/sun?/OBJ/mcp_async.o /sys/sun?/OBJ/mcp_async.o.orig
# mv /sys/sun?/OBJ/mti.o /sys/sun?/OBJ/mti.o.orig

# cp sun?/*.o /sys/sun?/OBJ/

rerun /etc/config <kernel-name> and do a "make" for the new kernel

Patch-ID# 100187-01
Keywords: TIOCCONS
Synopsis: SunOS 4.1 4.1_PSR_A: TIOCCONS redirection of console is a security violation.
Date: 17/Dec/90

SunOS release: 4.1 4.1_PSR_A

Unbundled Product:

Unbundled Release:

Topic:

BugId's fixed with this patch: 1008324

Architectures for which this patch is available: sun3 sun3x sun4 sun4c sun4-490_4.1_PSR_A

Patches which may conflict with this patch:

Obsoleted by: Next major release of SunOS

Problem Description

Patch contains kernel object modules for:

/sys/sun?/OBJ/cons.o
/sys/sun?/OBJ/zs_async.o
/sys/sun?/OBJ/mcp_async.o
/sys/sun?/OBJ/mti.o

NOTE: The sun4c does not use mti.o nor mcp_async.o since this architecture does not have VME slots and therefore cannot use the ALM-2 Asynchronous Line Multiplexed or Systech MTI-800/1600. So those modules are not needed.

The fix consists of adding permission checking to setcons, the routine that does the work of console redirection, and changing its callers to supply additional information required for the check and to see whether or not the check succeeded. Setcons now uses uid and gid information supplied to it as new arguments to perform a VOP_ACCESS call for VREAD permission on the console. If the caller doesn't have permission to read from the console, setcons rejects the redirection attempt.

Install

As Root:

# mv /sys/sun?/OBJ/cons.o /sys/sun?/OBJ/cons.o.orig
# mv /sys/sun?/OBJ/tty_pty.o /sys/sun?/OBJ/tty_pty.o.orig
# mv /sys/sun?/OBJ/zs_async.o /sys/sun?/OBJ/zs_async.o.orig
# mv /sys/sun?/OBJ/mcp_async.o /sys/sun?/OBJ/mcp_async.o.orig
# mv /sys/sun?/OBJ/mti.o /sys/sun?/OBJ/mti.o.orig

# cp sun?/*.o /sys/sun?/OBJ/

Please refer to the System and Network Administration Manual for details on how to configure and install a custom kernel.

CERT/CC Contact Information

Email: cert@cert.org
Phone: +1 412-268-7090 (24-hour hotline)
Fax: +1 412-268-6989
Postal address:

CERT Coordination Center
Software Engineering Institute
Carnegie Mellon University
Pittsburgh PA 15213-3890
U.S.A.

CERT/CC personnel answer the hotline 08:00-17:00 EST(GMT-5) / EDT(GMT-4) Monday through Friday; they are on call for emergencies during other hours, on U.S. holidays, and on weekends.

Using encryption

We strongly urge you to encrypt sensitive information sent by email. Our public PGP key is available from

http://www.cert.org/CERT_PGP.key

If you prefer to use DES, please call the CERT hotline for more information.

Getting security information

CERT publications and other security information are available from our web site

http://www.cert.org/

* "CERT" and "CERT Coordination Center" are registered in the U.S. Patent and Trademark Office.

NO WARRANTY
Any material furnished by Carnegie Mellon University and the Software Engineering Institute is furnished on an "as is" basis. Carnegie Mellon University makes no warranties of any kind, either expressed or implied as to any matter including, but not limited to, warranty of fitness for a particular purpose or merchantability, exclusivity or results obtained from use of the material. Carnegie Mellon University does not make any warranty of any kind with respect to freedom from patent, trademark, or copyright infringement.

Copyright 1990 Carnegie Mellon University.

September 17, 1997  Attacced copyright statement