oss-security - Re: CVE-2012-0862 assignment notification: xinetd enables unintentional services over tcpmux port

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Message-ID: <20120510070852.GA25491@openwall.com>
Date: Thu, 10 May 2012 11:08:52 +0400
From: Solar Designer <solar@...nwall.com>
To: oss-security@...ts.openwall.com
Cc: thomas.swan@...il.com, bbraun@...ack.net
Subject: Re: CVE-2012-0862 assignment notification: xinetd enables unintentional services over tcpmux port

On Wed, May 09, 2012 at 05:31:25PM +0200, Stefan Cornelius wrote:
> Thomas Swan of FedEx reported a service disclosure flaw in xinetd.
> xinetd allows for services to be configured with the TCPMUX or
> TCPMUXPLUS service types, which makes those services available on port
> 1, as per RFC 1078 [1], if the tcpmux-server service is enabled.  When
> the tcpmux-server service is enabled, xinetd would expose _all_ enabled
> services via the tcpmux port, instead of just the configured service(s).
> This could allow a remote attacker to bypass firewall restrictions and
> access services via the tcpmux port.
> 
> In order for enabled services handled by xinetd to be exposed via the
> tcpmux port, the tcpmux-server service must be enabled (by default it is
> disabled).
> 
> This has been assigned CVE-2012-0862.

This is now reported fixed in xinetd 2.3.15.  From xinetd-2.3.15/CHANGELOG:

2.3.15
        If the address we're binding to is a multicast address, do the
                multicast join.
        Merge the Fedora patch to turn off libwrap processing on tcp
                rpc services. Patch xinetd-2.3.12-tcp_rpc.patch.
        Merge the Fedora patch to add labeled networking.
                Patch xinetd-2.3.14-label.patch r1.4.
        Merge the Fedora patch to fix getpeercon() for labeled networking
                in MLS environments.
                Patch xinetd-2.3.14-contextconf.patch r1.1
        Merge the Fedora patch for int->ssize_t.
                Patch xinetd-2.3.14-ssize_t.patch r1.1
                Some modifications to this patch were necessary.
        Change compiler flags, -Wconversion generates excessive and
                unnecessary warnings with gcc, particularly all
                cases of ntohs(uint16_t).
                http://gcc.gnu.org/bugzilla/show_bug.cgi?id=6614
                Additionally add -Wno-unused to prevent unnecessary
                warnings regarding unused function parameters when
                the function is a callback conforming to a standard
                interface.
        Change version number to 2.3.15devel, indicating an interim
                developmental source snapshot.
        Merge patch from Thomas Swan regarding CVE-2012-0862

SHA-256 of xinetd-2.3.15.tar.gz that I just downloaded is
bf4e060411c75605e4dcbdf2ac57c6bd9e1904470a2f91e01ba31b50a80a5be3.
Unfortunately, there's no signature.

While we're at it, if anyone cares about these xinetd builtin services
and their issues (and it seems so), I think xinetd 2.3.14+ dropping
bad_port_check() is also a vulnerability that distros need to patch.
We do:

http://cvsweb.openwall.com/cgi/cvsweb.cgi/Owl/packages/xinetd/xinetd-2.3.14-up-revert-bad_port_check.diff?rev=1.1

(haven't updated to 2.3.15 yet, but that patch will stay the same - it
merely re-introduces the checks that existed in 2.3.13 and below).

Alexander

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