__________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN NXT BIND 8.2.x Overflow Vulnerability June 13, 2000 13:00 GMT Number K-050 ______________________________________________________________________________ PROBLEM: BIND versions 8.2, 8.2.1 and 8.2.2 will allow a buffer overflow condition, resulting in illegal remote access. PLATFORM: Red Hat, Solaris, FreeBSD, OpenBSD, NetBSD, Slackware. DAMAGE: A remote user will be able to gain root on the DNS server. SOLUTION: Upgrade BIND to version 8.2.2-P2. Preferably upgrade to the latest version 8.2.2-P5. ______________________________________________________________________________ VULNERABILITY The risk is HIGH. The exploit is publicly available. ASSESSMENT: ______________________________________________________________________________ Please note that older versions of BIND are not included in this discussion of the NXT Buffer Overflow vulnerability. There are security issues with older releases and should be upgraded to the latest release - 8.2.2-P5. If it is not possible to upgrade from version 4.x, for whatever reason, it is recommended that 4.9.7 be used. Scanning activity has increased on port 53 (named service). The scans are looking for systems running BIND version 8.2, 8.2.1 or 8.2.2. These versions of BIND are known to be on released versions of: Slackware 7.0 Red Hat 6.0, 6.1 Solaris 2.6, 2.7 Caldera OpenLinux 2.2 FreeBSD 3.2 OpenBSD 2.5 NetBSD 1.4.1 To determine the version of BIND running on a server type: dig @ version.bind chaos txt on any UNIX machine with the dig command installed. The output of the dig command will look like the following: ; <<>> DiG 8.2 <<>> @127.0.0.1 version.bind chaos txt ; (1 server found) ;; res options: init recurs defnam dnsrch ;; got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 6 ;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0 ;; QUERY SECTION: ;; version.bind, type = TXT, class = CHAOS ;; ANSWER SECTION: VERSION.BIND. 0S CHAOS TXT "8.2.2-P5" ;; Total query time: 4 msec ;; FROM: computer to SERVER: 127.0.0.1 ;; WHEN: Tue Jun 13 06:28:22 2000 ;; MSG SIZE sent: 30 rcvd: 63 Inside the ;; ANSWER SECTION is the version of BIND running on the server. How the exploit works The exploit requires two systems to be successful. The first is a DNS server that will have an altered DNS table. The second machine is where the attack will take place. Intruders alter a valid DNS server's (we will call this box [SERVER 1]) lookup table to point toward their computer [hacker.com] as the Authoritative Name Server for that domain. Intruders then prompt your DNS server to resolve [hacker.com]. [SERVER 1] passes the information back to your DNS server for the Authoritative Name Server for [hacker.com]. Your DNS server then goes to [hacker.com] looking to complete the query. Once your DNS server queries [hacker.com] for resolution, BIND runs and the buffer overflow condition occurs. Once the buffer overflow is executed, the following command is executed in the source code obtained by CIAC: cd /; uname -a; pwd; id;. The named service will crash as a result of the buffer overflow. To get the latest release of BIND (8.2.2-P5), go to: http://www.isc.org/products/BIND/bind8.html The following vendor patches are available as of May 25, 2000: Red Hat Linux 6.x: Intel: ftp://updates.redhat.com/6.1/i386/bind-8.2.2_P3-1.i386.rpm ftp://updates.redhat.com/6.1/i386/bind-devel-8.2.2_P3-1.i386.rpm ftp://updates.redhat.com/6.1/i386/bind-utils-8.2.2_P3-1.i386.rpm Alpha: ftp://updates.redhat.com/6.0/alpha/bind-8.2.2_P3-1.alpha.rpm ftp://updates.redhat.com/6.0/alpha/bind-devel-8.2.2_P3-1.alpha.rpm ftp://updates.redhat.com/6.0/alpha/bind-utils-8.2.2_P3-1.alpha.rpm Sparc: ftp://updates.redhat.com/6.0/sparc/bind-8.2.2_P3-1.sparc.rpm ftp://updates.redhat.com/6.0/sparc/bind-devel-8.2.2_P3-1.sparc.rpm ftp://updates.redhat.com/6.0/sparc/bind-utils-8.2.2_P3-1.sparc.rpm Source packages: ftp://updates.redhat.com/6.1/SRPMS/bind-8.2.2_P3-1.src.rpm Caldera ftp://ftp.calderasystems.com/pub/OpenLinux/updates/2.3/current SlackWare 7.0: ftp.cdrom.com:/pub/linux/slackware-7.0/patches/bind.tgz Sun Solaris 7.0_x86: Sun patch 107019-02 Sun patch 106939-03 Sun Solaris 7.0: Sun patch 107018-02 Sun patch 106938-03 _______________________________________________________________________________ CIAC wishes to acknowledge the contributions of Security Focus for 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). CIAC is located at the Lawrence Livermore National Laboratory in Livermore, California. CIAC is also a founding member of FIRST, the Forum of Incident Response and Security Teams, a global organization established to foster cooperation and coordination among computer security teams worldwide. CIAC services are available to DOE, DOE contractors, and the NIH. CIAC can be contacted at: Voice: +1 925-422-8193 FAX: +1 925-423-8002 STU-III: +1 925-423-2604 E-mail: ciac@llnl.gov For emergencies and off-hour assistance, DOE, DOE contractor sites, and the NIH may contact CIAC 24-hours a day. During off hours (5PM - 8AM PST), use one of the following methods to contact CIAC: 1. Call the CIAC voice number 925-422-8193 and leave a message, or 2. Call 888-449-8369 to send a Sky Page to the CIAC duty person or 3. Send e-mail to 4498369@skytel.com, or 4. Call 800-201-9288 for the CIAC Project Leader. Previous CIAC notices, anti-virus software, and other information are available from the CIAC Computer Security Archive. World Wide Web: http://www.ciac.org/ (or http://ciac.llnl.gov -- they're the same machine) Anonymous FTP: ftp.ciac.org (or ciac.llnl.gov -- they're the same machine) Modem access: +1 (925) 423-4753 (28.8K baud) +1 (925) 423-3331 (28.8K baud) PLEASE NOTE: Many users outside of the DOE, ESnet, and NIH computing communities receive CIAC bulletins. If you are not part of these communities, please contact your agency's response team to report incidents. Your agency's team will coordinate with CIAC. The Forum of Incident Response and Security Teams (FIRST) is a world-wide organization. A list of FIRST member organizations and their constituencies can be obtained via WWW at http://www.first.org/. This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation or favoring by the United States Government or the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or the University of California, and shall not be used for advertising or product endorsement purposes. 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