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AUSCERT External Security Bulletin Redistribution
ESB-97.095 -- Sun Security Bulletin #00147
Vulnerability in talkd
25 July 1997
Sun Microsystems, Inc. has released the following advisory concerning a
vulnerability in the talkd program. This vulnerability may allow local
and remote users to gain root access. This vulnerability has been publically
discussed and reported in AUSCERT advisory AA-97.01.
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.
A mirror of the patches mentioned in this advisory are available from:
Previous advisories and external security bulletins can be retrieved from:
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: firstname.lastname@example.org
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: #00147
Date: July 24, 1997
Cross-Ref: AUSCERT AA-97.01, CERT CA-97.04
Title: Vulnerability in talkd
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.
1. Bulletins Topics
Sun announces the release of patches for Solaris 2.5.1, 2.5, 2.4, and 2.3
(SunOS 5.5.1, 5.5, 5.4, and 5.3), SunOS 4.1.4 and 4.1.3_U1 which relate to
a vulnerability in the talkd program.
Sun strongly recommends that you install the patches listed in section 4
immediately on systems running SunOS 5.5.1, 5.5, 5.4, 5.3, 4.1.4, and
4.1.3_U1. Exploit information is publicly available.
2. Who is Affected
Vulnerable: SunOS versions 5.5.1, 5.5.1_x86, 5.5, 5.5_x86,
5.4, 5.4_x86, 5.3, 4.1.4, and 4.1.3_U1
The vulnerability is fixed in the upcoming release of Solaris.
3. Understanding the Vulnerability
The program talk provides a two-way, screen-oriented conversation between
users. The daemon talkd notitifes a user that another user wishes to
initiate a talk conversation. When a user initiates a talk conversation,
talkd performs a name service lookup for the name of the initiating host.
Due to insufficient bounds checking on the buffer where the hostname is
stored, it is possible to overwrite the internal stack space of the talkd
program. As talkd is setuid root, this vulnerability may be exploited by
intruders to remotely execute arbitrary commands with root privileges. To
exploit this vulnerability, attackers have to be able to make a network
connection to the vulnerable talkd program and provide corrupt hostname
information to that host.
4. List of Patches
The vulnerability in talkd is fixed by the following patches:
OS version Patch ID
SunOS 5.5.1 104692-01
SunOS 5.5.1_x86 104693-01
SunOS 5.5 104690-01
SunOS 5.5_x86 104691-01
SunOS 5.4 104701-01
SunOS 5.4_x86 104702-01
SunOS 5.3 104698-01
SunOS 4.1.4 104998-01
SunOS 4.1.3_U1 104997-01
5. Checksum Table
The checksum table below shows the BSD checksums (SunOS 4.1.x: /bin/sum;
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
These checksums may not apply if you obtain patches from your answer
File Name BSD SVR4 MD5
_______________ ________ _________ ________________________________
104692-01.tar.Z 05337 97 5296 194 0F45E5B9CCAD276AE166CAFFE9110799
104693-01.tar.Z 44228 97 39970 194 32D62F61E350AA6B50FBD2A4BA1059CA
104690-01.tar.Z 26808 97 47810 194 E4360074D6BB751C22406F1962556138
104691-01.tar.Z 07788 97 37926 194 B3519CA85BCD2CD818B1712B655E260F
104701-01.tar.Z 03035 85 2323 169 FCBEEAADE24029B9E5B0FB3CFAEE9CCE
104702-01.tar.Z 14433 85 29616 169 922599D5FF853181A9671070C7213F0D
104698-01.tar.Z 25487 85 52869 169 337DD394B381E4D61BA7E590ED1BBAD7
104998-01.tar.Z 46836 10 15721 19 8C62C5B5E0965BB0E0D3B5B835D98670
104997-01.tar.Z 21171 10 10506 19 DE1AE78A37570FD597AA39844554A3C7
Sun acknowledges with thanks AUSCERT and CERT/CC for their assistance in the
preparation of this bulletin.
Sun, AUSCERT, and CERT/CC are members of FIRST, the Forum of Incident Response
and Security Teams. For more information about FIRST, visit the FIRST web site
A. Patches listed in this bulletin are available to all Sun customers via
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