Published:
04 June 1997
Protect yourself against future threats.
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AUSCERT External Security Bulletin Redistribution
ESB-97.070 -- Sun Security Bulletin #00141
Vulnerability in getopt(3)
5 June 1997
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Sun Microsystems, Inc. has released the following advisory concerning a
vulnerability in getopt. This vulnerability may allow local users to gain
root access.
The following security bulletin is provided as a service to AUSCERT's
members. As AUSCERT did not write this document, AUSCERT has had no
control over its content. As such, the decision to use any or all of this
information is the responsibility of each user or organisation, and should
be done so in accordance with site policies and procedures.
Contact information for Sun Microsystems, Inc. is included in the Security
Bulletin below. If you have any questions or need further information,
please contact them directly.
Previous advisories and external security bulletins can be retrieved from:
http://www.auscert.org.au/information/advisories.html
If you believe that your system has been compromised, contact AUSCERT or your
representative in FIRST (Forum of Incident Response and Security Teams).
Internet Email: auscert@auscert.org.au
Facsimile: (07) 3365 4477
Telephone: (07) 3365 4417 (International: +61 7 3365 4417)
AUSCERT personnel answer during Queensland business hours
which are GMT+10:00 (AEST).
On call after hours for emergencies.
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Sun Microsystems, Inc. Security Bulletin
Bulletin Number: #00141
Date: 4 June 1997
Cross-Ref:
Title: Vulnerability in getopt(3)
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Permission is granted for the redistribution of this Bulletin, so long as
the Bulletin is not edited and is attributed to Sun Microsystems. Portions
may also be excerpted for re-use in other security advisories so long as
proper attribution is included.
Any other use of this information without the express written consent of
Sun Microsystems is prohibited. Sun Microsystems expressly disclaims all
liability for any misuse of this information by any third party.
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1. Bulletins Topics
Sun announces the release of patches for Solaris 2.5.1, 2.5, and 2.4
(SunOS 5.5.1, 5.5, and 5.4) that relate to a vulnerability with the
getopt(3) function in the libc library. Any privileged program (setuid
or setgid) that uses getopt(3) may exploit the vulnerability to gain root
access.
Sun estimates the release of patches for Solaris 2.4_x86 and 2.3 (SunOS
5.4_x86 and 5.3) that relate to the same vulnerability will be available
within 1 week and 3 weeks respectively of the date of this bulletin.
Sun strongly recommends that you:
a. install the patches listed in section 5 immediately on every system
running SunOS 5.5.1, 5.5.1_x86, 5.5, 5.5_x86, or 5.4
b. apply the workarounds specified in section 4 immediately on every system
running SunOS 5.4_x86 or 5.3.
2. Who is Affected
Vulnerable: SunOS versions 5.5.1, 5.5.1_x86, 5.5, 5.5_x86,
5.4, 5.4_x86, and 5.3.
Not vulnerable: All other supported versions of SunOS
This vulnerability is fixed in the upcoming release of Solaris.
3. Understanding the Vulnerability
The getopt(3) function parses options from a program's command list.
Due to insufficient bounds checking by getopt(3) while processing command
line arguments, it is possible to overwrite the internal stack space of
programs that use getopt(3). This may allow users to cause programs using
getopt(3) to execute arbitrary commands by supplying carefully crafted
arguments to these programs. If these programs are setuid or setgid, then
these commands may be run with those privileges.
Any dynamically or statically linked setuid or setgid program that uses
getopt(3) may be vulnerable.
4. Workarounds
4.1 Dynamically linked programs
The vulnerability can be exploited by using getopt(3) to print error
messages when an invalid option is discovered. These messages can be
suppressed by setting "opterr" (a global libc variable) to zero by doing
the following:
As root, execute the following command:
# adb -w /lib/libc.so.1
Type the following:
opterr?W0
The system will respond with:
opterr: 0x1 = 0x0
Type Control-D to exit adb.
Note that this workaround will suppress getopt(3) error messages from
all dynamically linked executables.
4.2 Statically linked programs
The workaround in 4.1 cannot be applied to statically linked setuid or
setgid programs. Other than /usr/sbin/static/rcp, Sun is not aware of any
other statically linked executable that uses getopt(3). The vulnerability
in the rcp program can be closed by removing the setuid bit with a command
such as the following:
chmod 555 /usr/sbin/static/rcp
The rcp program is typically run as root during system boot or recovery
only.
5. The vulnerability relating to getopt(3) is fixed by the following patches:
OS version Patch ID
---------- --------
SunOS 5.5.1 103612-23
SunOS 5.5.1_x86 103613-23
SunOS 5.5 103187-25
SunOS 5.5_x86 103188-25
SunOS 5.4 101945-49
SunOS 5.4_x86 101946-43 (to be released in 1 week)
SunOS 5.3 101318-87 (to be released in 3 weeks)
6. Checksum Table
The checksum table below shows the BSD checksums (SunOS 5.x: /usr/ucb/sum),
SVR4 checksums (SunOS 5.x: /usr/bin/sum), and the MD5 digital signatures
for the above-mentioned patches that are available from:
ftp://sunsolve1.sun.com/pub/patches/patches.html
These checksums may not apply if you obtain patches from your answer
centers.
File Name BSD SVR4 MD5
- --------------- --------- --------- --------------------------------
103612-23.tar.Z 58756 3133 30630 6266 80BFC84479DAED881141250D924C6B1A
103613-23.tar.Z 25868 2829 1295 5657 5AE2770752A17D853029B539EF94B783
103187-25.tar.Z 64511 3195 17448 6389 36120E6EB91C100EB302CE2FEE96739A
103188-25.tar.Z 07195 2880 23176 5760 6707EAB1BD10B845F535E131836F8DC5
101945-49.tar.Z 25995 10899 19660 21798 D67A5744C87BAD1A31D87AED6DC3C362
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Sun acknowledges with thanks AUSCERT, CERT/CC, and DFNCERT for their assistance
in the preparation of this bulletin.
Sun, AUSCERT, CERT/CC, and DFNCERT are members of FIRST, the Forum of Incident
Response and Security Teams. For more information about FIRST, visit the FIRST
web site at "http://www.first.org/".
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APPENDICES
A. Patches listed in this bulletin are available to all Sun customers via
World Wide Web at:
ftp://sunsolve1.sun.com/pub/patches/patches.html
Customers with Sun support contracts can also obtain patches from local
Sun answer centers and SunSITEs worldwide.
B. To report or inquire about a security problem with Sun software, contact
one or more of the following:
- Your local Sun answer centers
- Your representative computer security response team, such as CERT
- Sun Security Coordination Team. Send email to:
security-alert@sun.com
C. To receive information or subscribe to our CWS (Customer Warning System)
mailing list, send email to:
security-alert@sun.com
with a subject line (not body) containing one of the following commands:
Command Information Returned/Action Taken
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