-----BEGIN PGP SIGNED MESSAGE----- =========================================================================== AA-97.03 AUSCERT Advisory ftpd Signal Handling Vulnerability 29 January 1997 Last Revised: 19 August, 1997 Added vendor information for Silicon Graphics Inc. A complete revision history is at the end of this file. - --------------------------------------------------------------------------- AUSCERT has received information that there is a vulnerability in some versions of ftpd distributed and installed under various Unix platforms. This vulnerability may allow regular and anonymous ftp users to read or write to arbitrary files with root privileges. The vulnerabilities in ftpd affect various third party and vendor versions of ftpd. AUSCERT recommends that sites take the steps outlined in section 3 as soon as possible. This advisory will be updated as more information becomes available. - --------------------------------------------------------------------------- 1. Description AUSCERT has received information concerning a vulnerability in some vendor and third party versions of the Internet File Transfer Protocol server, ftpd(8). This vulnerability is caused by a signal handling routine increasing process privileges to root, while still continuing to catch other signals. This introduces a race condition which may allow regular, as well as anonymous ftp, users to access files with root privileges. Depending on the configuration of the ftpd server, this may allow intruders to read or write to arbitrary files on the server. This attack requires an intruder to be able to make a network connection to a vulnerable ftpd server. Sites should be aware that the ftp services are often installed by default. Sites can check whether they are allowing ftp services by checking, for example, /etc/inetd.conf: # grep -i '^ftp' /etc/inetd.conf Note that on some systems the inetd configuration file may have a different name or be in a different location. Please consult your documentation if the configuration file is not found in /etc/inetd.conf. If your site is offering ftp services, you may be able to determine the version of ftpd by checking the notice when first connecting. The vulnerability status of specific vendor and third party ftpd servers can be found in Section 3. Information involving this vulnerability has been made publicly available. 2. Impact Regular and anonymous users may be able to access arbitrary files with root privileges. Depending on the configuration, this may allow anonymous, as well as regular, users to read or write to arbitrary files on the server with root privileges. 3. Workarounds/Solution AUSCERT recommends that sites prevent the possible exploitation of this vulnerability by immediately applying vendor patches if they are available. Specific vendor information regarding this vulnerability is given in Section 3.1. If the ftpd supplied by your vendor is vulnerable and no patches are available, sites may wish to install a third party ftpd which does not contain the vulnerability described in this advisory (Section 3.2). 3.1 Vendor patches The following vendors have provided information concerning the vulnerability status of their ftpd distribution. Detailed information has been appended in Appendix A. If your vendor is not listed below, you should contact your vendor directly. Berkeley Software Design, Inc. Digital Equipment Corporation Hewlett-Packard Corporation IBM Corporation Red Hat Software Silicon Graphics Inc. Sun Microsystems The FreeBSD Project The NetBSD Project The OpenBSD Project Washington University ftpd (Academ beta version) Wietse Venema's logdaemon ftpd 3.2 Third party ftpd distributions AUSCERT has received information that the following third party ftpd distributions do not contain the signal handling vulnerability described in this advisory: wu-ftpd 2.4.2-beta-12 logdaemon 5.6 ftpd Sites should ensure they are using the current version of this software. Information on these distributions is contained in Appendix A. Sites should note that these third party ftpd distributions may offer some different functionality to vendor versions of ftpd. AUSCERT advises sites to read the documentation provided with the above third party ftpd distributions before installing. ........................................................................... Appendix A Berkeley Software Design, Inc. (BSDI) ===================================== BSD/OS 2.1 is vulnerable to the ftpd problem described in this advisory. Patches have been issued and may be retrieved via the email server or from: ftp://ftp.bsdi.com/bsdi/patches/patches-2.1/U210-033 Digital Equipment Corporation ============================= DIGITAL UNIX Versions: 3.2c, 3.2de1, 3.2de2, 3.2f, 3.2g, 4.0, 4.0a, 4.0b, 4.0c SOLUTION: This potential security vulnerability has been resolved and may be obtained from your normal Digital support channel or from the following URL. NOTE: Previously released singular ECO patches that were identified for this problem have been superseded in the aggregate versions of the ECO patch kits. ftp://ftp.service.digital.com/patches/public/dunix (Select the appropriate version and it's aggregate patch kit). Please refer to the applicable README notes information prior to the installation of patch kits on your system. - DIGITAL EQUIPMENT CORPORATION Hewlett-Packard Corporation =========================== AUSCERT has been informed that Hewlett-Packard has covered this in their security bulletin HPSBUX9702-055, 19 February 1997. The security bulletin contains pointers to the patches: SOLUTION: Apply patch: PHNE_10008 for all platforms with HP-UX releases 9.X PHNE_10009 for all platforms with HP-UX releases 10.0X/10.10 PHNE_10010 for all platforms with HP-UX releases 10.20 PHNE_10011 for all platforms with HP-UX releases 10.20 (kftpd) AVAILABILITY: All patches are available now. IBM Corporation =============== See the appropriate release below to determine your action. AIX 3.2 ------- Apply the following fix to your system: APAR - IX65536 (PTF - U447700) To determine if you have this PTF on your system, run the following command: lslpp -lB U447700 AIX 4.1 ------- Apply the following fix to your system: APAR - IX65537 To determine if you have this PTF on your system, run the following command: instfix -ik IX65537 Or run the following command: lslpp -h bos.net.tcp.client Your version of bos.net.tcp.client should be 4.1.5.3 or later. AIX 4.2 ------- Apply the following fix to your system: APAR - IX65538 To determine if you have this APAR on your system, run the following command: instfix -ik IX65538 Or run the following command: lslpp -h bos.net.tcp.client Your version of bos.net.tcp.client should be 4.2.1.0 or later. 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://service.software.ibm.com/aixsupport/ 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. Red Hat Software ================ The signal handling code in wu-ftpd has some security problems which allows users to read all files on your system. A new version of wu-ftpd is now available for Red Hat 4.0 which Red Hat suggests installing on all of your systems. This new version uses the same fix posted to redhat-list@redhat.com by Savochkin Andrey Vladimirovich. Users of Red Hat Linux versions earlier then 4.0 should upgrade to 4.0 and then apply all available security packages. Users whose computers have direct internet connections may apply this update by using one of the following commands: Intel: rpm -Uvh ftp://ftp.redhat.com/updates/4.0/i386/wu-ftpd-2.4.2b11-9.i386.rpm Alpha: rpm -Uvh ftp://ftp.redhat.com/updates/4.0/axp/wu-ftpd-2.4.2b11-9.axp.rpm SPARC: rpm -Uvhftp://ftp.redhat.com/updates/4.0/sparc/wu-ftpd-2.4.2b11-9.sparc.rpm All of these packages have been signed with Red Hat's PGP key. Silicon Graphics Inc. ===================== AUSCERT has been informed that Silicon Graphics Inc. has released patches which address the vulnerability discussed in this advisory. AUSCERT recommends that sites apply theses patches as soon as possible. OS Version Vulnerable? Patch # Other Actions ---------- ----------- ------- ------------- IRIX 3.x yes not avail Note 1 IRIX 4.x yes not avail Note 1 IRIX 5.0.x yes not avail Note 1 IRIX 5.1.x yes not avail Note 1 IRIX 5.2 yes not avail Note 1 IRIX 5.3 yes 2292 IRIX 6.0.x yes not avail Note 1 IRIX 6.1 yes not avail Note 1 IRIX 6.2 yes 1485 IRIX 6.3 no IRIX 6.4 no Note 1 recommends upgrading the operating system or disabling the ftp service. These patches can be retrieved from: http://www.sgi.com/Support/Secur/security.html Silicon Graphics has also released a security bulletin containing information on the above patches. The original release of this bulletin can be retrieved from: ftp://sgigate.sgi.com/security/19970801-01-PX Sun Microsystems ================ Sun Microsystems has informed AUSCERT that the ftpd distributed with Sun OS and Solaris is not vulnerable to this problem. The FreeBSD Project =================== The FreeBSD Project has informed AUSCERT that the vulnerability described in this advisory has been fixed in FreeBSD 2.1.7, all versions of FreeBSD 2.2 and FreeBSD-current (from January 27th, 1997). All previous versions of FreeBSD are vulnerable. The NetBSD Project =================== NetBSD (all versions) have the ftpd vulnerability described in this advisory. It has since been fixed in NetBSD-current. NetBSD have also made patches available and they can be retrieved from: ftp://ftp.netbsd.org/pub/NetBSD/misc/security/19970123-ftpd The OpenBSD Project =================== OpenBSD 2.0 did have the vulnerability described in this advisory, but has since been fixed in OpenBSD 2.0-current (from January 5, 1997). wu-ftpd Academ beta version =========================== The current version of wu-ftpd (Academ beta version), wu-ftpd 2.4.2-beta-12, does not contain the vulnerability described in this advisory. Sites using earlier versions should upgrade to the current version immediately. At the time of writing, the current version can be retrieved from: ftp://ftp.academ.com/pub/wu-ftpd/private/ logdaemon Distribution ====================== The current version of Wietse Venema's logdaemon (5.6) package contains an ftpd utility which addresses the vulnerability described in this advisory. Sites using earlier versions of this package should upgrade immediately. The current version of the logdaemon package can be retrieved from: ftp://ftp.win.tue.nl/pub/security/ ftp://ftp.auscert.org.au/pub/mirrors/ftp.win.tue.nl/logdaemon/ ftp://ftp.cert.dfn.de/pub/tools/net/logdaemon/ The MD5 checksum for Version 5.6 of the logdaemon package is: MD5 (logdaemon-5.6.tar.gz) = 5068f4214024ae56d180548b96e9f368 ........................................................................... - --------------------------------------------------------------------------- AUSCERT thanks David Greenman, Wietse Venema (visiting IBM T.J. Watson Research) and Stan Barber (Academ Consulting Services) for their contributions in finding solutions to this vulnerability. Thanks also to Dr Leigh Hume (Macquarie University), CERT/CC, and DFNCERT for their assistance in this matter. AUSCERT also thanks those vendors that provided feedback and patch information contained in this advisory. - --------------------------------------------------------------------------- The AUSCERT team have made every effort to ensure that the information contained in this document is accurate. However, the decision to use the information described is the responsibility of each user or organisation. The appropriateness of this document for an organisation or individual system should be considered before application in conjunction with local policies and procedures. AUSCERT takes no responsibility for the consequences of applying the contents of this document. If you believe that your system has been compromised, contact AUSCERT or your representative in FIRST (Forum of Incident Response and Security Teams). AUSCERT is located at The University of Queensland within the Prentice Centre. AUSCERT is a full member of the Forum of Incident Response and Security Teams (FIRST). AUSCERT maintains an anonymous FTP service which is found on: ftp://ftp.auscert.org.au/pub/. This archive contains past SERT and AUSCERT Advisories, and other computer security information. AUSCERT also maintains a World Wide Web service which is found on: http://www.auscert.org.au/. Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 4477 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AUSCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). On call after hours for emergencies. Postal: Australian Computer Emergency Response Team c/- Prentice Centre The University of Queensland Brisbane Qld. 4072. AUSTRALIA ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Revision History 19 Aug, 1997 Added vendor information for Silicon Graphics Inc. 12 Aug, 1997 Updated vendor information for DIGITAL UNIX. 17 Jun, 1997 Added updated vendor information Digital Equipment Corporation, for Hewlett-Packard Corporation, IBM Corporation, Sun Microsystems and The FreeBSD Project. 18 Apr, 1997 Added vendor information for DIGITAL UNIX. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -----BEGIN PGP SIGNATURE----- Version: 2.6.3i Charset: noconv Comment: ftp://ftp.auscert.org.au/pub/auscert/AUSCERT_PGP.key iQCVAwUBM/mIWyh9+71yA2DNAQEadAQAgHH7Z00piecZALjDF7lr/F7NtLv3uVow PKbE0T9Y1FfWGH+BTyflT912kdn6+He4jvG+oJZI0JwVGsFk6qHudhdA7pSiriwp v4iGNFYxZP9RuNgVNE/JUka9Yj4AUgHBMJyPmh+4Z2PtmcXS0JUO2jD9/VDUbZU8 9Tp1JRjaHKw= =J80Y -----END PGP SIGNATURE-----