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SuSE: 2002:033 Critical Advisory: OpenSSL Buffer Overflow by Slapper Worm

On July 30, we (SuSe) released a security advisory concerning vulnerabilities in OpenSSL, including a buffer overflow in the SSL code. This vulnerability is currently being exploited by a worm called Slapper, propagating through Apache's mod_ssl module. . ______________________________________________________________________________ SuSE Security Announcement Package: openssl/Slapper worm Announcement-ID: SuSE-SA:2002:033 Date: Thu Sep 19 2002 Affected products: 7.0, 7.1, 7.2, 7.3, 8.0 SuSE Linux Database Server, SuSE eMail Server III, SuSE eMail Server 3.1, SuSE Linux Enterprise Server, SuSE Linux Firewall on CD, SuSE Linux Enterprise Server 7 SuSE Linux Office Server Vulnerability Type: buffer overflow Severity (1-10): 9 SuSE default package: yes Cross References: CVE CAN-2002-0655, CAN-2002-0656, CAN-2002-0659, SuSE-SA:2002:027 Content of this advisory: 1) vulnerabilities in openssl libraries; Slapper worm 2) pending vulnerabilities, solutions, workarounds 3) standard appendix (further information) ______________________________________________________________________________ 1) problem description, brief discussion, solution, upgrade information This advisory is issued in an attempt to clarify any issues surrounding the recently discovered Apache/mod_ssl worm. On July 30, we released a security advisory concerning vulnerabilities in OpenSSL, including a buffer overflow in the SSL code. This vulnerability (CVE CAN-2002-0656, also discussed in CERT Advisory is currently being exploited by a worm calledSlapper, propagating through Apache's mod_ssl module. It is worth noting that even though the worm infects Apache through mod_ssl, this is not a vulnerability in mod_ssl or Apache, but in the OpenSSL library used by mod_ssl. This also means that Apache may not be the only service vulnerable to an attack via the SSL bug. Similar exploits may be possible against cyrus-imapd, sendmail with TLS support, or sslwrap-enabled services. As a workaround, it is also possible to disable SSLv2 in mod_ssl (as described in our previous advisory SuSE-SA:2002:027; SUSE – Open-Source-Lösungen für Enterprise Server und Cloud | SUSE but you should be aware that this does not protect other SSL based servers that may be running on your machine. We have received numerous inquiries from SuSE users on whether the update packages provided by SuSE as part of SA:2002:027 fix this bug even though they do not contain the latest OpenSSL version recommended in various advisories. To clarify this, we would like to state that these packages DO FIX the bug exploited by the Slapper worm. Following established policy, we did this by applying a source code patch instead of upgrading to a newer version, because the latter usually causes serious problems for many users (in particular, different versions of OpenSSL libraries are not always API compatible). However, it turns out that a number of packages were statically linked against OpenSSL libraries: mod_ssl (SuSE Linux 7.0): We have released rebuilt mod_ssl packages linked against the most recent OpenSSL libraries. If you run mod_ssl on SuSE Linux 7.0, you must upgrade mod_ssl, too. sendmail-tls (SuSE Linux 7.1, 7.2, 7.3): Sendmail-tls, the SSL enabled version of sendmail, was linked statically against OpenSSL on SuSE 7.1, 7.2 and 7.3. The security impact of this problem is probablythe same as with Apache and mod_ssl. We are releasing rebuilt packages linked against the most OpenSSL libraries. Sendmail-tls is not part of the default installation profile. If you are using sendmail-tls, we strongly recommend you upgrade to the latest packages provided on our FTP servers. openssh (SuSE Linux 7.1, 7.2 and 7.3): Ssh and sshd do not use any SSL functionality, and thus are not susceptible to the type of attack carried out by the Slapper worm. To date, we are not aware of any way to exploit them. We nevertheless recommend to upgrade to the latest versions provided on our FTP site. freeswan (SuSE Linux 7.1, 7.2): FreeSWAN includes a utility named fswcert for creating and manipulating X.509 certificates, which is also linked statically against libcrypto. To date, we are not aware of any way to exploit them. We nevertheless recommend to upgrade to the latest versions provided on our FTP site as soon as they become available (2002 Sep 20). ______________________________________________________________________________ 2) Pending vulnerabilities in SuSE Distributions and Workarounds: mod_php4: we are preparing an update of mod_php4 addressing various vulnerabilities that have been published recently. ______________________________________________________________________________ 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 toprove 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 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 This email address is being protected from spambots. You need JavaScript enabled to view it. ), 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 to verify the signature of the package, where 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 -" tobe root): gpg --batch; gpg < announcement.txt | gpg --import SuSE Linux distributions version 7.1 and thereafter install the key " This email address is being protected from spambots. You need JavaScript enabled to view it. " 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 . - SuSE runs two security mailing lists to which any interested party may subscribe: This email address is being protected from spambots. You need JavaScript enabled to view it. - general/linux/SuSE security discussion. All SuSE security announcements are sent to this list. To subscribe, send an email to . This email address is being protected from spambots. You need JavaScript enabled to view it. - SuSE's announce-only mailing list. Only SuSE's security annoucements are sent to this list. To subscribe, send an email to . For general information or the frequently asked questions (faq) send mail to: or respectively. ==================================================================== SuSE's security contact is or . The 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. Type Bits/KeyID Date User ID pub 2048R/3D25D3D9 1999-03-06 SuSE Security Team pub 1024D/9C800ACA 2000-10-19 SuSE Package Signing Key . Swift intervention is needed for OpenSSL and Slapper worm vulnerabilities in SuSE's Apache server configurations..OpenSSL Exploits, Slapper Worm Advisory, SuSE Security, Buffer Overflow Threats, Apache Risks. . Severity: Critical. LinuxSecurity.com Team

Apr 06, 2024 •Critical SuSE