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-----BEGIN PGP SIGNED MESSAGE----- =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2001.113 -- FreeBSD-SA-01:28.timed timed allows remote denial of service 13 March 2001 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: timed Vendor: FreeBSD Operating System: FreeBSD BSD Impact: Denial of Service Access Required: Remote - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- ============================================================================= FreeBSD-SA-01:28 Security Advisory FreeBSD, Inc. Topic: timed allows remote denial of service Category: core Module: timed Announced: 2001-03-12 Credits: Discovered during internal source code auditing Affects: All released versions of FreeBSD 3.x, 4.x. FreeBSD 3.5-STABLE prior to the correction date. FreeBSD 4.2-STABLE prior to the correction date. Corrected: 2001-03-10 (FreeBSD 3.5-STABLE) 2001-01-07 (FreeBSD 4.2-STABLE) FreeBSD only: NO I. Background timed(8) is a server for the Time Synchronisation Protocol, for synchronising the system clocks of multiple clients. II. Problem Description Malformed packets sent to the timed daemon could cause it to crash, thereby denying service to clients if timed is not run under a watchdog process which causes it to automatically restart in the event of a failure. The timed daemon is not run in this way in the default invocation from /etc/rc.conf using the timed_enable variable. The timed daemon is not enabled by default, and its use is not recommended (FreeBSD includes ntpd(8), the network time protocol daemon, which provides superior functionality). All versions of FreeBSD 3.x and 4.x prior to the correction date including 3.5.1-RELEASE and 4.2-RELEASE are vulnerable to this problem, if they have been configued to run timed. It was corrected prior to the forthcoming release of FreeBSD 4.3. III. Impact Remote users can cause the timed daemon to crash, denying service to clients. IV. Workaround Implement packet filtering at perimeter firewalls or on the local machine using ipfw(8)/ipf(8) to prevent untrusted users from connecting to the timed service. The timed daemon listens on UDP port 525 by default. V. Solution Upgrade your vulnerable FreeBSD system to 3.5-STABLE or 4.2-STABLE after the respective correction dates. To patch your present system: download the relevant patch from the below location, and execute the following commands as root: # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-01:28/timed.patch # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-01:28/timed.patch.asc This patch has been verified to apply to FreeBSD 4.2-RELEASE and FreeBSD 3.5.1-RELEASE. It may or may not apply to older releases. Verify the detached PGP signature using your PGP utility. # cd /usr/src/usr.sbin/timed/timed # patch -p < /path/to/patch # make depend && make all install Kill and restart timed to cause the changes to take effect. If you have started timed with non-standard options (e.g. by setting timed_flags in /etc/rc.conf) then the below command will need to be modified appropriately. # killall -KILL timed # /usr/sbin/timed - -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.4 (FreeBSD) Comment: For info see http://www.gnupg.org iQCVAwUBOq1emVUuHi5z0oilAQEYEwP/cPNMQO7LjlEs2/MyxJwVKpQLRzmprJjQ i2QpXEvkZgXSxAcIh15jNsR1TPwUnzCRWHZ5touw0DxTbTbMsnzRVx0/P5jGmQCT 6n5Z11puyEg336zET+tGhVnEt9Ybm7Z/h7Et+njVRTVqbe2AtpFeSbI5NXlZCgs6 ZUYxdLUhfPM= =Dw88 - -----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 iQCVAwUBOq4KZCh9+71yA2DNAQHqMAP/fbriixc5wAHTJ3mvCpI8EemqA5sLfxqN YJwFT1SRv/gefbJepP153xfloc5zYzBQjgHTl+9NqvgF0wDzsvyZfXrUfZFQHrcW CmG0BijJ8zAz8DcEyy9m1iR//794eiO+rZRGRLfYMqBo8whSiZGpDkNaiwKh1HII WFdH5LIwPCQ= =3dRN -----END PGP SIGNATURE-----