-----BEGIN PGP SIGNED MESSAGE----- CERT Advisory CA-2002-10 Format String Vulnerability in rpc.rwalld Original release date: May 1, 2002 Last revised: -- Source: CERT/CC A complete revision history can be found at the end of this file. Systems Affected * Sun Solaris 2.5.1, 2.6, 7, and 8 Overview The rwall daemon (rpc.rwalld) is a utility that is used to listen for wall requests on the network. When a request is received, it calls wall, which sends the message to all terminals of a time-sharing system. A format string vulnerability may permit an intruder to execute code with the privileges of the rwall daemon. A proof of concept exploit is publicly available, but we have not seen active scanning or exploitation of this vulnerability. I. Description rpc.rwalld is a utility that listens for remote wall requests. Wall is used to send a message to all terminals of a time-sharing system. If the wall command cannot be executed, the rwall daemon will display an error message. An intruder can consume system resources and potentially prevent wall from executing, which would trigger the rwall daemon's error message. A format string vulnerability exists in the code that displays the error message. This vulnerability may permit the intruder to execute code with the privileges of the rwall daemon. This vulnerability may be exploited both locally and remotely, although remote exploitation is significantly more difficult. II. Impact An intruder can execute code with the privileges of the rwall daemon, typically root. III. Solution Apply a patch Appendix A contains information provided by vendors for this advisory. If a patch is not available, disable the rwall daemon (rpc.rwalld) in inetd.conf until a patch can be applied. If disabling the rwall daemon is not an option, implement a firewall to limit access to rpc.rwalld (typically port 32777/UDP). Note that this will not mitigate all vectors of attack. Appendix A. - Vendor Information This appendix contains information provided by vendors for this advisory. As vendors report new information to the CERT/CC, we will update this section and note the changes in our revision history. If a particular vendor is not listed below, please check the Vulnerability Note (VU#638099) or contact your vendor directly. Hewlett-Packard HP is not vulnerable. IBM IBM's AIX operating system, versions 4.3.x and 5.1L, is not susceptible to the vulnerability described. NetBSD NetBSD has never been vulnerable to this problem. Sun Microsystems Sun confirms that there is a format string vulnerability in rpc.rwalld(1M) which affects Solaris 2.5.1, 2.6, 7 and 8. However, this issue relies on a combination of events, including the exhaustion of system resources, which are difficult to control by a remote user in order to be exploited. Disabling rpc.rwalld(1M) in inetd.conf(4) is the recommended workaround until patches are available. Sun is currently generating patches for this issue and will be releasing a Sun Security Bulletin once the patches are available. The bulletin will be available from: http://sunsolve.sun.com/security Sun patches are available from: http://sunsolve.sun.com/securitypatch _________________________________________________________________ The CERT Coordination Center acknowledges "GOBBLES" as the discoverer of this vulnerability and thanks Sun Microsystems for their technical information. _________________________________________________________________ Feedback can be directed to the author: Jason A. Rafail ______________________________________________________________________ This document is available from: http://www.cert.org/advisories/CA-2002-10.html ______________________________________________________________________ CERT/CC Contact Information Email: firstname.lastname@example.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/ To subscribe to the CERT mailing list for advisories and bulletins, send email to email@example.com. Please include in the body of your message subscribe cert-advisory * "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. _________________________________________________________________ Conditions for use, disclaimers, and sponsorship information Copyright 2002 Carnegie Mellon University. Revision History May 1, 2002: Initial release -----BEGIN PGP SIGNATURE----- Version: PGP 6.5.8 iQCVAwUBPNAuCKCVPMXQI2HJAQFPggP8CfV9uws6+YunrdNbxwEbKKopLCFRsL1Y Lk243wORHm3ocuWRWsqqWueaP/OuvG7lDS+0vOIsZlxUeKVZWWREUH8Lm2FMi3BB FRPTUWmjYqi3UcywqFnnZspXM+s9jL/fpRFBH1aqhIrpodB3+7HxqWEitll5vAJ4 c0WFy5v6S9k= =RnyP -----END PGP SIGNATURE-----
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