AST-2009-008: SIP responses expose valid usernames

           Asterisk Project Security Advisory - AST-2009-008

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| Product | Asterisk |
|----------------------±------------------------------------------------|
| Summary | SIP responses expose valid usernames |
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| Nature of Advisory | Information leak |
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| Susceptibility | Remote Unauthenticated Sessions |
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| Severity | Minor |
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| Exploits Known | No |
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| Reported On | October 26, 2009 |
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| Reported By | Patrik Karlsson <patrik AT cqure DOT net> |
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| Posted On | November 4, 2009 |
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| Last Updated On | November 4, 2009 |
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| Advisory Contact | Joshua Colp <jcolp AT digium DOT com> |
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| CVE Name | |
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| Description | It is possible to determine if a peer with a specific |
| | name is configured in Asterisk by sending a specially |
| | crafted REGISTER message twice. The username that is to |
| | be checked is put in the user portion of the URI in the |
| | To header. A bogus non-matching value is put into the |
| | username portion of the Digest in the Authorization |
| | header. If the peer does exist the second REGISTER will |
| | receive a response of "403 Authentication user name does |
| | not match account name". If the peer does not exist the |
| | response will be "404 Not Found" if alwaysauthreject is |
| | disabled and "401 Unauthorized" if alwaysauthreject is |
| | enabled. |
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| Resolution | Upgrade to one of the versions below, or apply one of the |
| | patches specified in the Patches section. |
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| Links | |
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| Asterisk Project Security Advisories are posted at |
| http://www.asterisk.org/security |
| |
| This document may be superseded by later versions; if so, the latest |
| version will be posted at |
| http://downloads.digium.com/pub/security/AST-2009-008.pdf and |
| http://downloads.digium.com/pub/security/AST-2009-008.html |
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           Asterisk Project Security Advisory - AST-2009-008
          Copyright (c) 2009 Digium, Inc. All Rights Reserved.

Permission is hereby granted to distribute and publish this advisory in its
original, unaltered form.