Asterisk Project Security Advisory - IAX2 provides a different response during authentication when a user does not exist, as compared to when the password is merely wrong. This allows an attacker to scan a host to find specific users on which to concentrate password cracking attempts.
76953e16708f452e52817ab659a4b7c085e7394015faca6b640857c346d8b1de Asterisk Project Security Advisory - AST-2009-001
+------------------------------------------------------------------------+
| Product | Asterisk |
|----------------------+-------------------------------------------------|
| Summary | Information leak in IAX2 authentication |
|----------------------+-------------------------------------------------|
| Nature of Advisory | Unauthorized data disclosure |
|----------------------+-------------------------------------------------|
| Susceptibility | Remote Unauthenticated Sessions |
|----------------------+-------------------------------------------------|
| Severity | Minor |
|----------------------+-------------------------------------------------|
| Exploits Known | Yes |
|----------------------+-------------------------------------------------|
| Reported On | October 15, 2008 |
|----------------------+-------------------------------------------------|
| Reported By | http://www.unprotectedhex.com |
|----------------------+-------------------------------------------------|
| Posted On | January 7, 2009 |
|----------------------+-------------------------------------------------|
| Last Updated On | January 7, 2009 |
|----------------------+-------------------------------------------------|
| Advisory Contact | Tilghman Lesher < tlesher AT digium DOT com > |
|----------------------+-------------------------------------------------|
| CVE Name | CVE-2009-0041 |
+------------------------------------------------------------------------+
+------------------------------------------------------------------------+
| Description | IAX2 provides a different response during authentication |
| | when a user does not exist, as compared to when the |
| | password is merely wrong. This allows an attacker to |
| | scan a host to find specific users on which to |
| | concentrate password cracking attempts. |
| | |
| | The workaround involves sending back responses that are |
| | valid for that particular site. For example, if it were |
| | known that a site only uses RSA authentication, then |
| | sending back an MD5 authentication request would |
| | similarly identify the user as not existing. The |
| | opposite is also true. So the solution is always to send |
| | back an authentication response that corresponds to a |
| | known frequency with which real authentication responses |
| | are returned, when the user does not exist. This makes |
| | it very difficult for an attacker to guess whether a |
| | user exists or not, based upon this particular |
| | mechanism. |
+------------------------------------------------------------------------+
+------------------------------------------------------------------------+
| Resolution | Upgrade to revision 167259 of the 1.2 branch or 167260 of |
| | the 1.4 branch or one of the releases noted below. |
+------------------------------------------------------------------------+
+------------------------------------------------------------------------+
| Affected Versions |
|------------------------------------------------------------------------|
| Product | Release | |
| | Series | |
|----------------------------+---------+---------------------------------|
| Asterisk Open Source | 1.2.x | All version prior to 1.2.31 |
|----------------------------+---------+---------------------------------|
| Asterisk Open Source | 1.4.x | All versions prior to |
| | | 1.4.23-rc4 |
|----------------------------+---------+---------------------------------|
| Asterisk Open Source | 1.6.x | All versions prior to |
| | | 1.6.0.3-rc2 |
|----------------------------+---------+---------------------------------|
| Asterisk Addons | 1.2.x | Not affected |
|----------------------------+---------+---------------------------------|
| Asterisk Addons | 1.4.x | Not affected |
|----------------------------+---------+---------------------------------|
| Asterisk Addons | 1.6.x | Not affected |
|----------------------------+---------+---------------------------------|
| Asterisk Business Edition | A.x.x | All versions |
|----------------------------+---------+---------------------------------|
| Asterisk Business Edition | B.x.x | All versions prior to B.2.5.7 |
|----------------------------+---------+---------------------------------|
| Asterisk Business Edition | C.1.x.x | All versions prior to C.1.10.4 |
|----------------------------+---------+---------------------------------|
| Asterisk Business Edition | C.2.x.x | All versions prior to C.2.1.2.1 |
|----------------------------+---------+---------------------------------|
| AsteriskNOW | 1.5 | Not affected |
|----------------------------+---------+---------------------------------|
| s800i (Asterisk Appliance) | 1.2.x | All versions prior to 1.3.0 |
+------------------------------------------------------------------------+
+------------------------------------------------------------------------+
| Corrected In |
|------------------------------------------------------------------------|
| Product | Release |
|--------------------------------------------+---------------------------|
| Asterisk Open Source | 1.2.31 |
|--------------------------------------------+---------------------------|
| Asterisk Open Source | 1.4.22.1 |
|--------------------------------------------+---------------------------|
| Asterisk Open Source | 1.6.0.3 |
|--------------------------------------------+---------------------------|
| Asterisk Business Edition | B.2.5.7 |
|--------------------------------------------+---------------------------|
| Asterisk Business Edition | C.1.10.4 |
|--------------------------------------------+---------------------------|
| Asterisk Business Edition | C.2.1.2.1 |
|--------------------------------------------+---------------------------|
| s800i (Asterisk Appliance) | 1.3.0 |
+------------------------------------------------------------------------+
+------------------------------------------------------------------------+
| Patches |
|------------------------------------------------------------------------|
| URL |Branch|
|-----------------------------------------------------------------+------|
|http://downloads.digium.com/pub/security/AST-2009-001-1.2.diff |1.2 |
|-----------------------------------------------------------------+------|
|http://downloads.digium.com/pub/security/AST-2009-001-1.4.diff |1.4 |
|-----------------------------------------------------------------+------|
|http://downloads.digium.com/pub/security/AST-2009-001-1.6.0.diff |1.6.0 |
+------------------------------------------------------------------------+
+------------------------------------------------------------------------+
| Links | http://code.google.com/p/iaxscan/ |
+------------------------------------------------------------------------+
+------------------------------------------------------------------------+
| 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-2009-001.pdf and |
| http://downloads.digium.com/pub/security/AST-2009-001.html |
+------------------------------------------------------------------------+
+------------------------------------------------------------------------+
| Revision History |
|------------------------------------------------------------------------|
| Date | Editor | Revisions Made |
|-----------------+------------------------+-----------------------------|
| 2009-01-07 | Tilghman Lesher | Initial release |
+------------------------------------------------------------------------+
Asterisk Project Security Advisory - AST-2009-001
Copyright (c) 2009 Digium, Inc. All Rights Reserved.
Permission is hereby granted to distribute and publish this advisory in its
original, unaltered form.
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