Date: Wed, 06 Apr 2011 20:18:12 +0200 From: Jan Lieskovsky <jlieskov@...hat.com> To: oss-security@...ts.openwall.com CC: "Steven M. Christey" <coley@...us.mitre.org>, Jiri Popelka <jpopelka@...hat.com> Subject: Re: CVE Request -- dhcp: DoS (excessive CPU use) by opening an OMAPI connection Jan Lieskovsky wrote: > > Hello Josh, Steve, vendors, > > A security flaw was found in the way DHCP (Dynamic Host Configuration > Protocol) > server processed remote connections when the dhcpd was configured to > provide > Object Management API (OMAPI) capability. A remote attacker could use > this flaw > to cause denial of service (excessive CPU use and dhcpd daemon > unreachability). > > References: >  https://bugzilla.novell.com/show_bug.cgi?id=680298 >  https://lists.isc.org/pipermail/dhcp-users/2011-February/012780.html >  https://lists.isc.org/pipermail/dhcp-users/2011-February/012781.html >  https://bugzilla.redhat.com/show_bug.cgi?id=666441 >  http://www.mentby.com/Group/dhcp-users/omapi-not-working-in-420.html > > Note: Though looks as minor / low severity issue, under proper > configuration > looks to be a way, how to get dhcpd completely unresponsive for > further > requests. > > Could you allocate a CVE id for this? (though opened for discussion if this > being more to be a bug, than a real security issue). The dhcpd(8) manual page:  http://linux.die.net/man/8/dhcpd suggests it's possible to "The control object allows you to shut the server down." [the Control Object section], but it also states: "OMAPI clients connect to the server using TCP/IP, authenticate, and can then examine the server's current status and make changes to it." and "The DHCP server exports the following objects: lease, host, failover-state and group." so not sure, if any (unprivileged) OMAPI client could shut down the server. Hopefully Jiri / someone else more familiar with OMAPI feature could shed more light into this (if each OMAPI client is able to shut down the dhcpd server => just bug or just privileged / authenticated one => potential DoS). Thanks && Regards, Jan. -- Jan iankko Lieskovsky / Red Hat Security Response Team
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