__________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN Multiple Vulnerabilities in BIND November 16, 1999 17:00 GMT Number K-007 ______________________________________________________________________________ PROBLEM: Six vulnerabilities have been identified in BIND, the popular domain name server from the Internet Software Consortium (ISC). The bugs are in 1) nxt, 2) sig, 3) so_linger, 4) fdmax, 5) maxdname, and 6) naptr. PLATFORM: BIND is distributed with many operating systems. DAMAGE: Exploits of these vulnerabilities could cause systems to crash or in the worst case, could allow an intruder to gain root access. SOLUTION: Apply vendor patches or update to the latest version of BIND. ______________________________________________________________________________ VULNERABILITY Risk is high. These vulnerabilities are being discussed on ASSESSMENT: Usenet newsgroups. ______________________________________________________________________________ [ Start CERT Advisory ] CERT Advisory CA-99-14 Multiple Vulnerabilities in BIND Original release date: November 10, 1999 Last revised: -- Source: CERT/CC A complete revision history is at the end of this file. Systems Affected * Systems running various versions of BIND I. Description Six vulnerabilities have been found in BIND, the popular domain name server from the Internet Software Consortium (ISC). One of these vulnerabilities may allow remote intruders to gain privileged access to name servers. Vulnerability #1: the "nxt bug" Some versions of BIND fail to properly validate NXT records. This improper validation could allow an intruder to overflow a buffer and execute arbitrary code with the privileges of the name server. NXT record support was introduced in BIND version 8.2. Prior versions of BIND, including 4.x, are not vulnerable to this problem. The ISC-supplied version of BIND corrected this problem in version 8.2.2. Vulnerability #2: the "sig bug" This vulnerability involves a failure to properly validate SIG records, allowing a remote intruder to crash named; see the impact section for additional details. SIG record support is found in multiple versions of BIND, including 4.9.5 through 8.x. Vulnerability #3: the "so_linger bug" By intentionally violating the expected protocols for closing a TCP session, remote intruders can cause named to pause for periods up to 120 seconds. Vulnerability #4: the "fdmax bug" Remote intruders can consume more file descriptors than BIND can properly manage, causing named to crash. Vulnerability #5: the "maxdname bug" Improper handling of certain data copied from the network could allow a remote intruder to disrupt the normal operation of your name server, possibly including a crash. Vulnerability #6: the "naptr bug" Some versions of BIND fail to validate zone information loaded from disk files. In environments with unusual combinations of permissions and protections, this could allow an intruder to crash named. Other recent BIND-related vulnerabilities AusCERT recently published a report describing denial-of-service attacks against name servers. These attacks are unrelated to the issues described in this advisory. For information on the denial-of-service attacks described by AusCERT, please see AusCERT Alert AL-1999.004 available at: ftp://ftp.auscert.org.au/pub/auscert/advisory/AL-1999.004.dns_dos II. Impact Vulnerability #1 By exploiting this vulnerability, remote intruders can execute arbitrary code with the privileges of the user running named, typically root. Vulnerabilities #2, #4, and #5 By exploiting these vulnerabilities, remote intruders can disrupt the normal operation of your name server, possibly causing a crash. Vulnerability #3 By periodically exercising this vulnerability, remote intruders can disrupt the ability of your name server to respond to legitimate queries. By intermittently exercising this vulnerability, intruders can seriously degrade the performance of your name server. Vulnerability #6 Local intruders who gain write access to your zone files can cause named to crash. III. Solution Apply a patch from your vendor or update to a later version of BIND Many operating system vendors distribute BIND with their operating system. Depending on your support procedures, arrangements, and contracts, you may wish to obtain BIND from your operating system vendor rather than directly from ISC. Appendix A contains information provided by vendors 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 Vendor Name Caldera See ftp://ftp.calderasystems.com/pub/OpenLinux/updates/2.3/current MD5s db1dda05dbe0f67c2bd2e5049096b42c RPMS/bind-8.2.2p3-1.i386.rpm 82bbe025ac091831904c71c885071db1 RPMS/bind-doc-8.2.2p3-1.i386.rpm 2f9a30444046af551eafd8e6238a50c6 RPMS/bind-utils-8.2.2p3-1.i386.rpm 0e4f041549bdd798cb505c82a8911198 SRPMS/bind-8.2.2p3-1.src.rpm Compaq Computer Corporation At the time of writing this document, Compaq is currently investigating the potential impact to Compaq's BIND release(s). As further information becomes available Compaq will provide notice of the completion/availability of any necessary patches through AES services (DIA, DSNlink FLASH and posted to the Services WEB page) and be available from your normal Compaq Services Support channel. Data General We are investigating. We will provide an update when our investigation is complete. Hewlett-Packard Company HP is vulnerable, see the chart in the ISC advisory for details on your installed version of BIND. Our fix strategy is under investigation, watch for updates to this CERT advisory in the CERT archives, or an HP security advisory/bulletin. IBM Corporation The bind8 shipped with AIX 4.3.x is vulnerable. We are currently working on the following APARs which will be available soon: APAR 4.3.x: IY05851 To Order APARs may be ordered using Electronic Fix Distribution (via FixDist) or from the IBM Support Center. For more information on FixDist, reference URL: http://aix.software.ibm.com/aix.us/swfixes/ or send e-mail to aixserv@austin.ibm.com with a subject of "FixDist". IBM and AIX are registered trademarks of International Business Machines Corporation. The Internet Software Consortium ISC has published an advisory regarding these problems, available at http://www.isc.org/products/BIND/bind-security-19991108.html The ISC advisory also includes a table summarizing which versions of BIND are susceptible to the vulnerabilities described in this advisory. OpenBSD As far as we know, we don't ship with any of those vulnerabilities. Santa Cruz Operation, Inc Security patches for the following SCO products will be made available at http://www.sco.com/security OpenServer 5.x.x, UnixWare 7.x.x, UnixWare 2.x.x Sun Microsystems Vulnerability #1 Solaris 2.3, 2.4, 2.5, 2.5.1, 2.6, and 7 are not vulnerable. Vulnerability #2 Solaris 2.3, 2.4, 2.5, 2.5.1, 2.6, and 7 are not vulnerable. Vulnerability #3 Solaris 2.3, 2.4, 2.5, 2.5.1, and 2.6 are not vulnerable. Sun will be producing patches for Solaris 7. Vulnerability #4 Solaris 2.3, 2.4, 2.5, 2.5.1, and 2.6 are not vulnerable. Solaris 7 is probably not vulnerable. We are still investigating. Vulnerability #5 Solaris 2.3, 2.4, 2.5, 2.5.1, and 2.6 are not vulnerable. Sun will be producing patches for Solaris 7. Vulnerability #6 Solaris 2.3, 2.4, 2.5, 2.5.1, and 2.6 are not vulnerable. Sun will be producing patches for Solaris 7. _________________________________________________________________ The CERT Coordination Center would like to thank David Conrad, Paul Vixie and Bob Halley of the Internet Software Consortium for notifying us of these problems and for their help in constructing the advisory, and Olaf Kirch of Caldera for notifying us of some of these problems and providing technical assistance and advice. ______________________________________________________________________ This document is available from: http://www.cert.org/advisories/CA-99-14-bind.html ______________________________________________________________________ [ End CERT Advisory ] ______________________________________________________________________________ CIAC wishes to acknowledge the contributions of CERT for the information contained in this bulletin. ______________________________________________________________________________ CIAC, the Computer Incident Advisory Capability, is the computer security incident response team for the U.S. Department of Energy (DOE) and the emergency backup response team for the National Institutes of Health (NIH). 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