____________________________________________________________________________ SuSE Security Announcement Package: dhcp/dhcp-server Announcement-ID: SuSE-SA:2002:019 Date: Wednesday, May 22th 2002 13:30 MEST Affected products: 7.2, 7.3, 8.0 SuSE Linux Database Server SuSE eMail Server III SuSE Linux Enterprise Server for S/390 SuSE Linux Connectivity Server SuSE Linux Enterprise Server 7 Vulnerability Type: remote command execution Severity (1-10): 4 SuSE default package: no Other affected systems: all systems using ISC DHCP server 3.x Content of this advisory: 1) security vulnerability resolved: format string bug in dynamic DNS code problem description, discussion, solution and upgrade information 2) pending vulnerabilities, solutions, workarounds 3) standard appendix (further information) ____________________________________________________________________________ 1) problem description, brief discussion, solution, upgrade information The "Dynamic Host Configuration Protocol" (DHCP) server from the Internet Software Consortium allows hosts on a TCP/IP network to request and be assigned IP addresses, and also to discover information about the network to which they are attached. A remote exploitable format string vulnerability was found in the logging routines of the dynamic DNS code of dhcpd. This vulnerability allows an attacker, usually within the LAN served by the DHCP server, to get remote root access to the host running dhcpd. The dhcp/dhcp-server package is not installed by default nor is the dynamic DNS feature enabled by default. As temporary workaround the dynamic DNS feature could be disabled via dhcpd's config file with the following lines: ddns-update-style none; ddns-updates off; After updating the package or modifying the config file you have to run: rcdhcpd restart as root to restart all instances of running dhcpd processes. Please download the update package for your distribution and verify its integrity by the methods listed in section 3) of this announcement. Then, install the package using the command "rpm -Fhv file.rpm" to apply the update. Our maintenance customers are being notified individually. The packages are being offered to install from the maintenance web. i386 Intel Platform: SuSE-8.0 ftp://ftp.suse.com/pub/suse/i386/update/8.0/n2/dhcp-server-3.0.1rc6-8.i386.rpm 754569c059f5f2c4f71397f6c6498f53 source rpm: ftp://ftp.suse.com/pub/suse/i386/update/8.0/zq1/dhcp-3.0.1rc6-8.src.rpm 82ab4455ae86a932a746778ca0cf06f1 SuSE-7.3 ftp://ftp.suse.com/pub/suse/i386/update/7.3/n2/dhcp-3.0rc12-47.i386.rpm 58bdf5e4e0622ba280fad0d649a36bdd source rpm: ftp://ftp.suse.com/pub/suse/i386/update/7.3/zq1/dhcp-3.0rc12-47.src.rpm 20abdc3bad4810971aa4cc959c133a9e SuSE-7.2 ftp://ftp.suse.com/pub/suse/i386/update/7.2/n2/dhcp-3.0rc4-27.i386.rpm 826ffc2524ad6a6b3b746e3c5e0e5413 source rpm: ftp://ftp.suse.com/pub/suse/i386/update/7.2/zq1/dhcp-3.0rc4-27.src.rpm 7bfd527698beef5a83e60577e7e02cfb Sparc Platform: SuSE-7.3 ftp://ftp.suse.com/pub/suse/sparc/update/7.3/n2/dhcp-3.0rc12-22.sparc.rpm 15ec49d27e7f8b61ec22616484e43996 source rpm: ftp://ftp.suse.com/pub/suse/sparc/update/7.3/zq1/dhcp-3.0rc12-22.src.rpm 1e3f0ee6da5684a49b31908f0e6ac9dd PPC Power PC Platform: SuSE-7.3 ftp://ftp.suse.com/pub/suse/ppc/update/7.3/n2/dhcp-3.0rc12-32.ppc.rpm 76914c072100dff6fdf781ed81f7afeb source rpm: ftp://ftp.suse.com/pub/suse/ppc/update/7.3/zq1/dhcp-3.0rc12-32.src.rpm 9ac78f35a529c24315f11184555c7f81 ____________________________________________________________________________ 2) Pending vulnerabilities in SuSE Distributions and Workarounds: - tcpdump/libpcap Various security and non-security related bugs were found in the code of tcpdump and libpcap. New RPMs are currently being build. ____________________________________________________________________________ 3) standard appendix: authenticity verification, additional information - Package authenticity verification: SuSE update packages are available on many mirror ftp servers all over the world. While this service is being considered valuable and important to the free and open source software community, many users wish to be sure about the origin of the package and its content before installing the package. There are two verification methods that can be used independently from each other to prove the authenticity of a downloaded file or rpm package: 1) md5sums as provided in the (cryptographically signed) announcement. 2) using the internal gpg signatures of the rpm package. 1) execute the command md5sum <name-of-the-file.rpm> after you downloaded the file from a SuSE ftp server or its mirrors. Then, compare the resulting md5sum with the one that is listed in the announcement. Since the announcement containing the checksums is cryptographically signed (usually using the key firstname.lastname@example.org), the checksums show proof of the authenticity of the package. We disrecommend to subscribe to security lists which cause the email message containing the announcement to be modified so that the signature does not match after transport through the mailing list software. Downsides: You must be able to verify the authenticity of the announcement in the first place. If RPM packages are being rebuilt and a new version of a package is published on the ftp server, all md5 sums for the files are useless. 2) rpm package signatures provide an easy way to verify the authenticity of an rpm package. Use the command rpm -v --checksig <file.rpm> to verify the signature of the package, where <file.rpm> is the filename of the rpm package that you have downloaded. Of course, package authenticity verification can only target an uninstalled rpm package file. Prerequisites: a) gpg is installed b) The package is signed using a certain key. The public part of this key must be installed by the gpg program in the directory ~/.gnupg/ under the user's home directory who performs the signature verification (usually root). You can import the key that is used by SuSE in rpm packages for SuSE Linux by saving this announcement to a file ("announcement.txt") and running the command (do "su -" to be root): gpg --batch; gpg < announcement.txt | gpg --import SuSE Linux distributions version 7.1 and thereafter install the key "email@example.com" upon installation or upgrade, provided that the package gpg is installed. The file containing the public key is placed at the toplevel directory of the first CD (pubring.gpg) and at ftp://ftp.suse.com/pub/suse/pubring.gpg-build.suse.de . - SuSE runs two security mailing lists to which any interested party may subscribe: firstname.lastname@example.org - general/linux/SuSE security discussion. All SuSE security announcements are sent to this list. To subscribe, send an email to <email@example.com>. firstname.lastname@example.org - SuSE's announce-only mailing list. Only SuSE's security annoucements are sent to this list. To subscribe, send an email to <email@example.com>. For general information or the frequently asked questions (faq) send mail to: <firstname.lastname@example.org> or <email@example.com> respectively. ===================================================================== SuSE's security contact is <firstname.lastname@example.org> or <email@example.com>. The <firstname.lastname@example.org> public key is listed below. ===================================================================== ____________________________________________________________________________ The information in this advisory may be distributed or reproduced, provided that the advisory is not modified in any way. In particular, it is desired that the cleartext signature shows proof of the authenticity of the text. SuSE Linux AG makes no warranties of any kind whatsoever with respect to the information contained in this security advisory. Bye, Thomas -- Thomas Biege <email@example.com> SuSE Linux AG,Deutschherrnstr. 15-19,90429 Nuernberg Function: Security Support & Auditing "lynx -source http://www.suse.de/~thomas/contact/thomas.asc | pgp -fka" Key fingerprint = 51 AD B9 C7 34 FC F2 54 01 4A 1C D4 66 64 09 83 -- Trete durch die Form ein, und trete aus der Form heraus.
May 22, 2002
SuSE Linux Advisory: dhcp/dhcp server
SuSE: "A remote exploitable format string vulnerability was found in the logging routines of the dynamic DNS code of dhcpd. This vulnerability allows an attacker, usually within the LAN served by the DHCP server, to get remote root access to the host running dhcpd."