The information has been provided by Oliver Goebel.
The original article can be found at: http://cert.uni-stuttgart.de/advisories/al-ip-touch-vlan-filtering.php
* Alcatel-Lucent OmniPCX Enterprise Release 7.0 and later with IEEE 802.1x authentication enabled and default configuration for the PC port of the mini switch integrated in IP Touch telephones
* Alcatel-Lucent OmniPCX Enterprise Release 7.0 and later when the PC port of the IP Touch telepone's mini switch either is configured to
- 'disabled port' with no daisy-chained computer system or
- 'filtering port' with a computer system is daisy-chained.
Note: IEEE 802.1x is not implemented in earlier versions of OmniPCX Enterprise nor on OmniPCX Office.
Insecure default configurations in Alcatel-Lucent's Voice-over-IP Telephone System OmniPCX Enterprise Release 7.0 and later can be exploited to gain un-authenticated access to the voice VLAN through daisy chained computer systems. By default the mini switch built into the IP Touch telephone is enabled in a configuration vulnerable to the issue described in this document. Changing the configuration in a specific way remediates the problem. The scope of this document is limited to 802.1x- and 801.1q-enabled infrastructures. In scenarios not using 802.1x authentication, access to the voice VLAN is trivial.
Alcatel-Lucent was contacted in 02-2007 and the publication of this announcement was co-ordinated with A-L's PSIRT and development department.
Who Should Read this Document:
* Users of Alcatel-Lucent OmniPCX Enterprise Release 7.0 and later operating Alcatel-Lucent IP Touch telephones in a network configuration that uses IEEE 802.1q (VLAN) technology to separate voice and data traffic (VLAN segmentation) and .
* Mini switch in Alcatel-Lucent IP Touch telephone when daisy-chaining a IEEE 802.1q capable computer system
* Physical access to the built-in mini switch in an Alcatel-Lucent IP Touch telephone; In a typical configuration this will be provided by a daisy-chained computer system. If this system is compromised, the attack can be performed remotely.
* Improper configuration of the PC port state on the IP Touch's mini switch; This is the default.
To successfully attack an infrastructure the following extra requirements must be met:
* IEEE 801.1q VLAN segmentation must be used to separate the "voice network" from other networks
* IEEE 802.1x authentication must be enabled to authenticate telephones and control their access to the voice VLAN
Both technologies are recommended and commonly used in VoIP environments.
* Un-authenticated access to the VLAN defined to separate voice traffic from data traffic
The built-in mini switch in Alcatel-Lucent IP-Touch telephones does not properly filter VLAN traffic received in multicast or broadcast mode and thus does not prevent it from being forwarded to daisy-chained equipment.
This fact effectively invalidates the IEEE 802.1x mechanism for daisy-chained devices because the daisy-chained device gets partial access to the tagged VLAN without performing an authentication. The telephone performs the authentication and then acts as a hub for a subset of the voice VLAN traffic.
If no cryptographic mechanisms are implemented, negotiations using broadcast or multicast traffic within the Voice-VLAN are done in clear text (e.g. DHCP, ARP). Hence, a daisy-chained device or PC is able to see this information.
Negotiations performed by the telephone using unicast traffic are not seen by the daisy-chained device. So, the device does not see the IP address assigned to the telephone because the DHCP server usually sends DHCPOFFER messages in unicast mode.
Nevertheless, daisy-chained devices can determine the telephone's hardware address by analyzing the broadcast traffic unintentionally sent from the switch. When initiating the DHCP process the telephone sends a broadcast message to the server that includes its hardware address.
A human attacker having physical access to the telephone can obtain the telephone's hardware address and IP address by using the 'Options' menu in the telephone's GUI. The GUI can be protected by a password preventing disclosure of the addresses to an unprivileged user.
This vulnerability can be exploited in the following scenarios:
1. An attacker having physical access to the mini switch in a telephone would be able to access the Voice VLAN and all resources available to the telephone. This could be used to conduct various attacks on the telephony equipment including some denial-of-service attacks and attempts to compromise the systems.
2. An attacker being able to remotely compromise a PC in a daisy-chained configuration would be able to gain partial access to the Voice VLAN and all ressources available to the telephone. This could be used to conduct various attacks on the telephony equipment including denial-of-service attacks and attempts to compromise the systems.
3. Since protocols and technology that are used to get access to the telephony VLAN are standardized, attacks can be automated. Consequently, a much higher threat arises from the fact that such attacks can be built into malware that automatically performs them and that can be deployed via a worm or bot. In a daisy-chained configuration an infected computer system can become a threat to the telephony network.
Users of OmniPCX Enterprise Release 7.x are advised to configure the PC port status to:
- 'disabled port' if no computer system is daisy-chained to the telephone or
- to 'filtering port' if a computer system is daisy-chained.
More Information on This Issue
* See Alcatel-Lucent PSIRT's Security Statements Page for Alcatel-Lucent's Announcement on this issue.
 http://en.wikipedia.org/wiki/DHCP, http://archive.cert.uni-stuttgart.de/rfc/rfc2131.txt and http://archive.cert.uni-stuttgart.de/rfc/rfc3315.txt
 http://en.wikipedia.org/wiki/Address_Resolution_Protocol, http://archive.cert.uni-stuttgart.de/rfc/rfc826.txt