Threat Level: green Handler on Duty: Brad Duncan

SANS ISC: ntpd upgrade to prevent spoofed looping SANS ISC InfoSec Forums

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ntpd upgrade to prevent spoofed looping

Martin wrote in to point to VU #568372. It contains a description of a vulnerability (CVE-2009-3563) in the reference implementation of ntpd, which will sound very familiar for any dog owner seeing his pet chase it's own tail. Basically all that's needed is a single spoofed packet to set of ntp daemons to start endlessly sending messages to themselves or to each-other.

Filtering in the short term is a possible workaround, but upgrading your ntp software to at least version 4.2.4p8 is a far better long term strategy.

Note that this software is often embedded in various devices and operating systems, so upgrading it might take a bit of effort in tracking it all down.

Swa Frantzen -- Section 66


760 Posts
Dec 9th 2009

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