Samba 3.0 DoS Vulnerabilities (CAN-2004-0807 & CAN-2004-0808)

[Gerald (Jerry) Carter]

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Subject:	Samba 3.0.x Denial of Service Flaw

Summary:	(i) A DoS bug in smbd may allow an
		unauthenticated user to cause smbd to
		spawn new processes each one entering
		an infinite loop.  After sending a sufficient
		amount of packets it is possible to exhaust
		the memory resources on the server.

		(ii) A DoS bug in nmbd may allow an attacker
		to remotely crash the nmbd daemon.

Affected
Versions:	Defect (i) affects Samba 3.0.x prior to and
		including v3.0.6.

		Defect (ii) affects Samba 3.0.x prior to
		and including v3.0.6.

Patch
Availability:	The patch file for Samba 3.0.5 addressing both
		bugs (samba-3.0.5-DoS.patch) can be downloaded
		from
		http://download.samba.org/samba/ftp/patches/security/


Description
- -----------

CAN-2004-0807: A defect in smbd's ASN.1 parsing allows an
attacker to send a specially crafted packet during the
authentication request which will send the newly spawned
smbd process into an infinite loop.  Given enough of these
packets, it is possible to exhaust the available memory
on the server.

CAN-2004-0808: A defect in nmbd's process of mailslot packets
can allow an attacker to anonymously crash nmbd.


Protecting Unpatched Servers
- ----------------------------

The Samba Team always encourages users to run the latest stable
release as a defense of against attacks.  However, under certain
circumstances it may not be possible to immediately upgrade
important installations.  In such cases, administrators should
read the "Server Security" documentation found at
http://www.samba.org/samba/docs/server_security.html.


Credits
- --------

Both security issues were reported to Samba developers by
iDEFENSE (http://www.idefense.com/).  The defect discovery
was anonymously reported to iDEFENSE via their Vulnerability
Contributor Program (http://www.idefense.com/poi/teams/vcp.jsp).


- --
Our Code, Our Bugs, Our Responsibility.


				-- The Samba Team


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