Vulnerability Note VU#726548

Voice mail systems allow administrative access based on Caller ID

Overview

Certain voice mail systems trust Calling Number Identification (CNID, Caller ID) to authenticate administrative access to voice mail accounts. Caller ID can be easily spoofed, allowing an attacker to gain control over a vulnerable voice mailbox.

I. Description

Some voice mail systems use Caller ID to authenticate administrative access to individual voice mail accounts. If the Caller ID of an inbound call matches the number assigned to the telephone associated with the voice mailbox, the system assumes that the call is originating from that phone, and the call is routed to the voice mailbox with administrative privileges. The party originating the call can then listen to and delete messages, modify the greeting, and perform other administrative functions. Some systems ring the phone first, others do not.

Caller ID can be readily spoofed using freely available PBX software and a H.323/VOIP gateway service, and possibly via other methods. Caller ID should not be trusted for authentication.

Depending on available product features and default configurations, voice mail service providers may or may not have the option to use Caller ID to authenticate administrative access to voice mail accounts. There are two groups represented in the Systems Affected section of this document: voice mail product/system vendors and voice mail service providers. A vendor is noted as "Not Vulnerable" if their products do not allow Caller ID to be used for authentication by default or do not allow it at all. A service provider is noted as "Not Vulnerable" if their voice mail services do not rely on Caller ID for authentication.

II. Impact

An attacker can gain administrative access to a voice mailbox. Depending on the system, the attacker could listen to and delete messages, change the greeting message, or make other modifications. By changing the greeting message, an attacker may be able to charge calls to an account with a vulnerable voice mail system:

http://www.wired.com/news/infostructure/0,1377,58517,00.html

Any system that relies solely on caller ID for authentication may be vulnerable to impersonation or spoofing attacks.

III. Solution

Require password authentication

If possible, configure voice mail systems to require a password/PIN to authenticate access to administrative account functions. A unique default password should be assigned to each voice mail account.

Systems Affected

Vendor	Status	Date Notified
3Com	Unknown	30-May-2003
Alcatel	Unknown	30-May-2003
Allied Telesis	Unknown	31-Jan-2007
AT&T	Unknown	30-May-2003
Avaya	Not Vulnerable	24-Jun-2003
Cable and Wireless	Not Vulnerable	30-May-2003
Cisco Systems, Inc.	Unknown	2-Jun-2003
Hewlett-Packard Company	Unknown	2-Jun-2003
IBM Corporation	Unknown	30-May-2003
Lucent Technologies	Vulnerable	7-Aug-2003
MCI	Unknown	8-Aug-2003
Mediatrix Telecom Inc	Not Vulnerable	2-Jul-2003
MetaSwitch	Unknown	31-Jan-2007
Mitel	Not Vulnerable	30-May-2003
Motorola	Unknown	30-May-2003
NetIQ	Unknown	31-Jan-2007
Nokia	Unknown	30-May-2003
Nortel Networks, Inc.	Vulnerable	15-Jul-2003
Pingtel	Not Vulnerable	5-Jun-2003
Polycom	Unknown	31-Jan-2007
Qwest	Unknown	8-Aug-2003
RAD Data Communications	Unknown	31-Jan-2007
SBC	Unknown	8-Aug-2003
Shoreline Communication	Not Vulnerable	23-Jun-2003
Siemens	Unknown	4-Jun-2003
Sphere	Unknown	31-Jan-2007
Sprint	Vulnerable	30-May-2003
StarVox	Unknown	31-Jan-2007
T-Mobile	Vulnerable	30-May-2003

References

http://www.cpsr.org/program/caller-id/caller-id.html
http://www.eff.org/Privacy/Caller_ID/
http://www.wired.com/news/infostructure/0,1377,58517,00.html
http://www.securityfocus.com/news/6158
http://www.securityfocus.com/news/9061
http://www.securityfocus.com/news/9419

Credit

This vulnerability was reported by Gus Bourg.

This document was written by Art Manion.

Other Information

Date Public:	2007-01-30
Date First Published:	2007-01-30
Date Last Updated:	2007-03-30
CERT Advisory:
CVE-ID(s):
NVD-ID(s):
US-CERT Technical Alerts:
Metric:	9.22
Document Revision:	29

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Produced 2007 by US-CERT, a government organization
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