Protect yourself against future threats.
-----BEGIN PGP SIGNED MESSAGE----- =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2000.352 -- FreeBSD-SA-00:71 mgetty can create or overwrite files 21 November 2000 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: mgetty Vendor: FreeBSD Ports Collection Operating System: FreeBSD BSD Linux Impact: Denial of Service Access Required: Local Ref: ESB-2000.259 - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- ============================================================================= FreeBSD-SA-00:71 Security Advisory FreeBSD, Inc. Topic: mgetty can create or overwrite files Category: ports Module: mgetty Announced: 2000-11-20 Credits: Stan Bubrouski <satan@FASTDIAL.NET> Affects: Ports collection prior to the correction date. Corrected: 2000-9-10 Vendor status: Updated version released FreeBSD only: NO I. Background mgetty is a replacement for the getty utility designed for use with data and fax modems. II. Problem Description The mgetty port, versions prior to 1.1.22.8.17, contains a vulnerability that may allow local users to create or overwrite any file on the system. This is due to the faxrunqd daemon (which usually runs as root) following symbolic links when creating a .last_run file in the world-writable /var/spool/fax/outgoing/ directory. This presents a denial of service attack since the attacker can cause critical system files to be overwritten, but it is not believed the attacker has the ability to control the contents of the overwritten file. Therefore the possibility of using this attack to elevate privileges is believed to be minimal. The mgetty port is not installed by default, nor is it "part of FreeBSD" as such: it is part of the FreeBSD ports collection, which contains over 4100 third-party applications in a ready-to-install format. The ports collections shipped with FreeBSD 3.5.1 and 4.1.1 contain this problem since it was discovered after the releases, but it was corrected prior to the release of FreeBSD 4.2. FreeBSD makes no claim about the security of these third-party applications, although an effort is underway to provide a security audit of the most security-critical ports. III. Impact Unprivileged local users may create or overwrite any file on the system. If you have not chosen to install the mgetty port/package, then your system is not vulnerable to this problem. IV. Workaround Deinstall the mgetty port/package, if you you have installed it. V. Solution One of the following: 1) Upgrade your entire ports collection and rebuild the mgetty port. 2) Deinstall the old package and install a new package dated after the correction date, obtained from: ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-3-stable/comms/mgetty-1.1.22.8.17.tgz ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-4-stable/comms/mgetty-1.1.22.8.17.tgz ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/alpha/packages-4-stable/comms/mgetty-1.1.22.8.17.tgz ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-5-current/comms/mgetty-1.1.22.8.17.tgz ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/alpha/packages-5-current/comms/mgetty-1.1.22.8.17.tgz 3) download a new port skeleton for the mgetty port from: http://www.freebsd.org/ports/ and use it to rebuild the port. 4) Use the portcheckout utility to automate option (3) above. The portcheckout port is available in /usr/ports/devel/portcheckout or the package can be obtained from: ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-3-stable/devel/portcheckout-2.0.tgz ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-4-stable/devel/portcheckout-2.0.tgz ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/alpha/packages-4-stable/devel/portcheckout-2.0.tgz ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-5-current/devel/portcheckout-2.0.tgz ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/alpha/packages-5-current/devel/portcheckout-2.0.tgz - -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.4 (FreeBSD) Comment: For info see http://www.gnupg.org iQCVAwUBOhmWG1UuHi5z0oilAQE5jAP+Lj1qI76n/cHjmfR05NTckZ4EI1Fkt708 zZfEL9B4y8FCgluw9nLNhVKHYjkQFg/b0SEgBetElPu+k6ivcu9EqI2Gk4RIyT82 HJFqOOnvX2yodMgZo1NozEot3aw3DIQg8TFs0Z/w0E4e+02iCytPmZYfrE5vbWif q1qAcFpgJWE= =l2yv - -----END PGP SIGNATURE----- - --------------------------END INCLUDED TEXT-------------------- This security bulletin is provided as a service to AusCERT's members. As AusCERT did not write the document quoted above, AusCERT has had no control over its content. The decision to use any or all of this information is the responsibility of each user or organisation, and should be done so in accordance with site policies and procedures. NOTE: This is only the original release of the security bulletin. It may not be updated when updates to the original are made. If downloading at a later date, it is recommended that the bulletin is retrieved directly from the original authors to ensure that the information is still current. Contact information for the authors of the original document is included in the Security Bulletin above. If you have any questions or need further information, please contact them directly. Previous advisories and external security bulletins can be retrieved from: http://www.auscert.org.au/Information/advisories.html If you believe that your system has been compromised, contact AusCERT or your representative in FIRST (Forum of Incident Response and Security Teams). Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 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. -----BEGIN PGP SIGNATURE----- Version: 2.6.3i Charset: noconv Comment: ftp://ftp.auscert.org.au/pub/auscert/AUSCERT_PGP.key iQCVAwUBOlSNQih9+71yA2DNAQF/5gP8C4zm1AgX4sFkmpyJXRP+78g21eqckECz vR4bTeDMv5X9XcnohLKYApYAkb01yVZ086esB44ymtRXNQJZNJvEwMrzU6+GwDEj dR1G3Rjhbmaah6KtmQXcdieGBDsdtaHbbRh8YFfOFg5ysxJb7Bh0Q6QuXc92i4hf i0v4VDguIhE= =EWQK -----END PGP SIGNATURE-----