Published:
28 February 1999
Protect yourself against future threats.
-----BEGIN PGP SIGNED MESSAGE----- =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-1999.028 -- NetBSD Security Advisory 1999-004 traceroute can create untraceable packet floods 01 March 1999 =========================================================================== The NetBSD Foundation, Inc. has released the following advisory concerning a vulnerability in traceroute. This vulnerability may allow remote users to create untraceable packet floods. - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- NetBSD Security Advisory 1999-004 ================================= Topic: traceroute can create untraceable packet floods Version: NetBSD 1.3.3 and prior; NetBSD-current until 19990217 Severity: Unauthorized users can flood remote hosts with a forged source address. Abstract ======== By feeding traceroute(1) with invalid arguments the time delay between packets sent is set to zero resulting in all packets sent out very fast, possibly flooding the remote host with packets containing a false source address. Technical Details ================= When setting the wait time for each packet the argument was not sanity checked possibly causing select(2) to return immediately after sending out a packet instead of waiting for reply. The return value of a select(2) call was not properly checked causing a flood of packets to be sent to the remote host. This is exacerbated by the fact that traceroute(1) allowed non-root users to set the source address for these packets, allowing them to appear to come from any address, possibly making it extremely difficult to identify the real source of the flood. Solutions and Workarounds ========================= A patch is available for the NetBSD 1.3.3 source, which fixes the above problems. You may find this patch on the NetBSD ftp server: ftp://ftp.NetBSD.ORG/pub/NetBSD/misc/security/patches/19990217-traceroute The patch contains details on how to apply it. As a temporary measure, you can allow only privileged users to run traceroute by disabling its setuid bit: chmod u-s /usr/sbin/traceroute Thanks To ========= Thanks go out to the members of the Bugtraq mailing list where this problem was first discussed. Also, many thanks to Curt Sampson <cjs@NetBSD.ORG> who fixed the problem in NetBSD-current and to Hubert Feyrer <hubertf@NetBSD.ORG> for the patch to NetBSD-1.3.3 and the coordination of this security advisory. More Information ================ Information about NetBSD and NetBSD security can be found at http://www.NetBSD.ORG/ and http://www.NetBSD.ORG/Security/. Copyright 1999, The NetBSD Foundation, Inc. All Rights Reserved. $NetBSD: NetBSD-SA1999-004.txt,v 1.1 1999/02/28 00:45:56 mrg Exp $ - -----BEGIN PGP SIGNATURE----- Version: 2.6.3ia Charset: noconv iQCVAwUBNtiSnD5Ru2/4N2IFAQHN+gQAyRP/VTze3CFwM5HFkVv20IjIHnCYWuHH s+QRhxukEXVgLJJ8w85WXoWSdKj8VPpsIZcZFOp5ceSLKc5IRL2U4k4ys/ChTNF7 /WOywEbZPkSljiaWTMAxwQpYhacEnFfAodc/ALsqSE61ZQTNU3k2ZFogfYZQDdZZ fGLxyQtc3vs= =lxzQ - -----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 will 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 iQCVAwUBNuO2ICh9+71yA2DNAQEo7QQAnPsQcxFxQpE0BUWkdnR0ztHe7a5hr/xA 39Ih7fn9bMC5ZG9NijiZI0kdL52f29lXhf3sTzt6a5wzi+FKq0Jav5ZA4rLroIJ0 dV+X/x6p+vsnSUun31beQsWl/rRaTuTxyFi5CiyPvF66YBdyYg6MSQff7A3TpLFq eCvJWltSvJc= =0sar -----END PGP SIGNATURE-----