FedCIRC Advisory FA-99-07 Original issue date: June 9, 1999 Source: CERT/CC Revised Date: July 22, 1999 Added link to IN-99-04 in the "Description" section. Systems Affected Systems running older versions of rpc.statd and automountd I. Description This advisory describes two vulnerabilities that are being used together by intruders to gain access to vulnerable systems. The first vulnerability is in rpc.statd, a program used to communicate state changes among NFS clients and servers. The second vulnerability is in automountd, a program used to automatically mount certain types of file systems. Both of these vulnerabilities have been widely discussed on public forums, such as [1]BugTraq, and some vendors have issued security advisories related to the problems discussed here. Because of the number of incident reports we have received, however, we are releasing this advisory to call attention to these problems so that system and network administrators who have not addressed these problems do so immediately. For more information about attacks using various RPC services please see CERTŪ Incident Note IN-99-04 [2]http://www.cert.org/incident_notes/IN-99-04.html The vulnerability in rpc.statd allows an intruder to call arbitrary rpc services with the privileges of the rpc.statd process. The called rpc service may be a local service on the same machine or it may be a network service on another machine. Although the form of the call is constrained by rpc.statd, if the call is acceptable to another rpc service, the other rpc service will act on the call as if it were an authentic call from the rpc.statd process. The vulnerability in automountd allows a local intruder to execute arbitrary commands with the privileges of the automountd process. This vulnerability has been widely known for a significant period of time, and patches have been available from vendors, but many systems remain vulnerable because their administrators have not yet applied the appropriate patches. By exploiting these two vulnerabilities simultaneously, a remote intruder is able to "bounce" rpc calls from the rpc.statd service to the automountd service on the same targeted machine. Although on many systems the automountd service does not normally accept traffic from the network, this combination of vulnerabilities allows a remote intruder to execute arbitrary commands with the administrative privileges of the automountd service, typically root. Note that the rpc.statd vulnerability described in this advisory is distinct from the vulnerabilities described in CERT Advisories [3]CA-96.09 and [4]CA-97.26. II. Impact The vulnerability in rpc.statd may allow a remote intruder to call arbitrary rpc services with the privileges of the rpc.statd process, typically root. The vulnerablility in automountd may allow a local intruder to execute arbitrary commands with the privileges of the automountd service. By combining attacks exploiting these two vulnerabilities, a remote intruder is able to execute arbitrary commands with the privileges of the automountd service. Note It may still be possible to cause rpc.statd to call other rpc services even after applying patches which reduce the privileges of rpc.statd. If there are additional vulnerabilities in other rpc services (including services you have written), an intruder may be able to exploit those vulnerabilities through rpc.statd. At the present time, we are unaware of any such vulnerabilitity that may be exploited through this mechanism. III. Solutions Install a patch from your vendor Appendix A contains input from vendors who have provided information for this advisory. We will update the appendix as we receive more information. If you do not see your vendor's name, the CERT/CC did not hear from that vendor. Please contact your vendor directly. Appendix A: Vendor Information Caldera Caldera's currently not shipping statd. Compaq Computer Corporation (c) Copyright 1998, 1999 Compaq Computer Corporation. All rights reserved. SOURCE: Compaq Computer Corporation Compaq Services Software Security Response Team USA This reported problem has not been found to affect the as shipped, Compaq's Tru64/UNIX Operating Systems Software. - Compaq Computer Corporation Data General We are investigating. We will provide an update when our investigation is complete. Hewlett-Packard Company HP is not vulnerable. The Santa Cruz Operation, Inc. No SCO products are vulnerable. Silicon Graphics, Inc. % IRIX % rpc.statd IRIX 6.2 and above ARE NOT vulnerable. IRIX 5.3 is vulnerable, but no longer supported. % automountd With patches from SGI Security Advisory 19981005-01-PX installed, IRIX 6.2 and above ARE NOT vulnerable. % Unicos Currently, SGI is investigating and no further information is available for public release at this time. As further information becomes available, additional advisories will be issued via the normal SGI security information distribution method including the wiretap mailing list. SGI Security Headquarters [5]http://www.sgi.com/Support/security Sun Microsystems Inc. The following patches are available: rpc.statd: Patch OS Version _____ __________ 106592-02 SunOS 5.6 106593-02 SunOS 5.6_x86 104166-04 SunOS 5.5.1 104167-04 SunOS 5.5.1_x86 103468-04 SunOS 5.5 103469-05 SunOS 5.5_x86 102769-07 SunOS 5.4 102770-07 SunOS 5.4_x86 102932-05 SunOS 5.3 The fix for this vulnerability was integrated in SunOS 5.7 (Solaris 7) before it was released. automountd: 104654-05 SunOS 5.5.1 104655-05 SunOS 5.5.1_x86 103187-43 SunOS 5.5 103188-43 SunOS 5.5_x86 101945-61 SunOS 5.4 101946-54 SunOS 5.4_x86 101318-92 SunOS 5.3 SunOS 5.6 (Solaris 2.6) and SunOS 5.7 (Solaris 7) are not vulnerable. Sun security patches are available at: [6]http://sunsolve.sun.com/pub-cgi/show.pl?target=patches/patch -license&nav=pub-patches _______________________________________________________________ Our thanks to Olaf Kirch of Caldera for his assistance in helping us understand the problem and Chok Poh of Sun Microsystems for his assistance in helping us construct this advisory. _______________________________________________________________ This document is available from: [7]http://www2.fedcirc.gov/advisories/FA-99-07.html _______________________________________________________________ FedCIRC Contact Information Email: [8]fedcirc@fedcirc.gov Phone: +1 888-282-0870 (24-hour toll-free hotline) Phone: +1 412-268-6321 (24-hour hotline) Fax: +1 412-268-6989 Postal address: FedCIRC CERT Coordination Center Software Engineering Institute Carnegie Mellon University Pittsburgh PA 15213-3890 U.S.A. FedCIRC personnel answer the hotline 08:00-20:00 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 [9]http://www2.fedcirc.gov/keys.html If you prefer to use DES, please call the FedCIRC hotline for more information. Getting security information FedCIRC publications and other security information are available from our web site [10]http://www.fedcirc.gov/ FedCIRC (Federal Computer Incident Response Capability) is operated by the CERT/CC for the U.S. General Services Administration. FedCIRC provides security services to U.S. Federal civilian agencies. Copyright 1999 Carnegie Mellon University. Conditions for use, disclaimers, and sponsorship information can be found in [11]http://www.cert.org/legal_stuff.html * "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. Revision History July 22, 1999 Added link to IN-99-04 in the "Description" section. References 1. http://www.netspace.org/lsv-archive/bugtraq.html 2. http://www.cert.org/incident_notes/IN-99-04.html 3. http://www.cert.org/advisories/CA-96.09.rpc.statd.html 4. http://www.cert.org/advisories/CA-97.26.statd.html 5. http://www.sgi.com/Support/security/ 6. http://sunsolve.sun.com/pub-cgi/show.pl?target=patches/patch-license&nav=pub-patches 7. http://www2.fedcirc.gov/advisories/FA-99-07.html 8. mailto:fedcirc@fedcirc.gov 9. http://www2.fedcirc.gov/keys.html 10. http://www.fedcirc.gov/ 11. http://www.cert.org/legal_stuff.html