[VOIPSEC] ASA-2007-014: Stack buffer overflow in IAX2 channel driver
Raul Siles
raul.siles at gmail.com
Tue Jul 17 20:45:04 CDT 2007
May I suggest everyone to also review the other three new
vulnerabilities (015 to 017)?
Thanks!
--
Raul Siles
--
The Asterisk development team has released Asterisk versions 1.2.22 and
1.4.8.
These releases contain fixes for four critical security vulnerabilities.
One of these vulnerabilities is a remotely exploitable stack buffer
overflow, which could allow an attacker to execute arbitrary code on the
target machine. The other three are all remotely exploitable crash
vulnerabilities.
We have released Asterisk Security Advisories for each of the
vulnerabilities. The current version of each advisory can be downloaded
from the ftp site.
http://ftp.digium.com/pub/asa/ASA-2007-014.pdf
* Affected systems include those that bridge calls between chan_iax2
and any channel driver that uses RTP for media
http://ftp.digium.com/pub/asa/ASA-2007-015.pdf
* Affected systems include any system that has chan_iax2 enabled
http://ftp.digium.com/pub/asa/ASA-2007-016.pdf
* Affected systems include any system that has chan_skinny enabled
http://ftp.digium.com/pub/asa/ASA-2007-017.pdf
* Affected systems include any 1.4 system that has any channel driver
that uses RTP for media enabled
All users that have systems that meet any of the criteria listed above
should upgrade as soon as possible.
Thank you very much for your support.
--
On 7/18/07, Kevin P. Fleming <kpfleming at digium.com> wrote:
> Asterisk Project Security Advisory - ASA-2007-014
>
> +------------------------------------------------------------------------+
> | Product | Asterisk |
> |----------------------+-------------------------------------------------|
> | Summary | Stack buffer overflow in IAX2 channel driver |
> |----------------------+-------------------------------------------------|
> | Nature of Advisory | Exploitable Stack Buffer Overflow |
> |----------------------+-------------------------------------------------|
> | Susceptibility | Remote Unauthenticated Sessions |
> |----------------------+-------------------------------------------------|
> | Severity | Critical |
> |----------------------+-------------------------------------------------|
> | Exploits Known | No |
> |----------------------+-------------------------------------------------|
> | Reported On | July 12, 2007 |
> |----------------------+-------------------------------------------------|
> | Reported By | Russell Bryant, Digium, Inc. |
> |----------------------+-------------------------------------------------|
> | Posted On | July 17, 2007 |
> |----------------------+-------------------------------------------------|
> | Last Updated On | July 17, 2007 |
> |----------------------+-------------------------------------------------|
> | Advisory Contact | Russell Bryant <russell at digium.com> |
> |----------------------+-------------------------------------------------|
> | CVE Name | CVE-2007-3762 |
> +------------------------------------------------------------------------+
>
> +------------------------------------------------------------------------+
> | Description | The Asterisk IAX2 channel driver, chan_iax2, has a |
> | | remotely exploitable stack buffer overflow |
> | | vulnerability. It occurs when chan_iax2 is passed a |
> | | voice or video frame with a data payload larger than 4 |
> | | kB. This is exploitable by sending a very large RTP |
> | | frame to an active RTP port number used by Asterisk when |
> | | the other end of the call is an IAX2 channel. Exploiting |
> | | this issue can cause a crash or allow arbitrary code |
> | | execution on a remote machine. |
> | | |
> | | The specific conditions that trigger the vulnerability |
> | | are the following: |
> | | |
> | | * iax2_write() is called with a frame with the |
> | | following properties |
> | | |
> | | * a voice or video frame |
> | | |
> | | * Its 4-byte timestamp has the same high 2 bytes |
> | | as the previous frame that was sent |
> | | |
> | | * Its format is the one currently expected |
> | | |
> | | * Its data payload is larger than 4 kB |
> | | |
> | | iax2_write() calls iax2_send() to send the frame. Inside |
> | | of iax2_send(), there is a conditional check to |
> | | determine whether the frame should be sent immediately |
> | | (the now variable) or queued for transmission later. |
> | | |
> | | If the frame is going to be transmitted later, an |
> | | iax_frame struct is dynamically allocated with a data |
> | | buffer that has the exact buffer size needed to |
> | | accommodate for the provided ast_frame data. However, if |
> | | the frame is being sent immediately, it uses a stack |
> | | allocated iax_frame, with a data buffer size of 4096 |
> | | bytes. |
> | | |
> | | Later, the iax_frame_wrap() function is used to copy the |
> | | data from the ast_frame struct into the iax_frame |
> | | struct. This function assumes the iax_frame data buffer |
> | | has enough space for all of the data in the ast_frame. |
> +------------------------------------------------------------------------+
>
> +------------------------------------------------------------------------+
> | Resolution | This issue is only exploitable when the system is |
> | | configured in such a way that calls between channels that |
> | | use RTP and IAX2 channels are possible. Also, some |
> | | additional protection against arbitrary code execution is |
> | | provided if the call involves transcoding between audio |
> | | formats as this will change the contents of the frame |
> | | payload. |
> | | |
> | | All users that have systems that connect calls between |
> | | channels that use RTP and IAX2 channels should |
> | | immediately update to versions listed in the corrected in |
> | | section of this advisory. |
> +------------------------------------------------------------------------+
>
> +------------------------------------------------------------------------+
> | Affected Versions |
> |------------------------------------------------------------------------|
> | Product | Release | |
> | | Series | |
> |----------------------------------+-------------+-----------------------|
> | Asterisk Open Source | 1.0.x | All versions |
> |----------------------------------+-------------+-----------------------|
> | Asterisk Open Source | 1.2.x | All versions prior to |
> | | | 1.2.22 |
> |----------------------------------+-------------+-----------------------|
> | Asterisk Open Source | 1.4.x | All versions prior to |
> | | | 1.4.8 |
> |----------------------------------+-------------+-----------------------|
> | Asterisk Business Edition | A.x.x | All versions |
> |----------------------------------+-------------+-----------------------|
> | Asterisk Business Edition | B.x.x | All versions prior to |
> | | | B.2.2.1 |
> |----------------------------------+-------------+-----------------------|
> | AsteriskNOW | pre-release | All versions prior to |
> | | | beta7 |
> |----------------------------------+-------------+-----------------------|
> | Asterisk Appliance Developer Kit | 0.x.x | All versions prior to |
> | | | 0.5.0 |
> |----------------------------------+-------------+-----------------------|
> | s800i (Asterisk Appliance) | 1.0.x | All versions prior to |
> | | | 1.0.2 |
> +------------------------------------------------------------------------+
>
> +------------------------------------------------------------------------+
> | Corrected In |
> |------------------------------------------------------------------------|
> | Product | Release |
> |-------------------+----------------------------------------------------|
> | Asterisk Open | 1.2.22 and 1.4.8, available from |
> | Source | ftp://ftp.digium.com/pub/telephony/asterisk |
> |-------------------+----------------------------------------------------|
> | Asterisk Business | B.2.2.1, available from the Asterisk Business |
> | Edition | Edition user portal on http://www.digium.com or |
> | | |
> | | via Digium Technical Support |
> |-------------------+----------------------------------------------------|
> | AsteriskNOW | Beta7, available from http://www.asterisknow.org/. |
> | | Beta5 and Beta6 users can update using the system |
> | | update feature in the appliance control panel. |
> |-------------------+----------------------------------------------------|
> | Asterisk | 0.5.0, available from |
> | Appliance | |
> | Developer Kit | ftp://ftp.digium.com/pub/telephony/aadk/ |
> |-------------------+----------------------------------------------------|
> | s800i (Asterisk | 1.0.2 |
> | Appliance) | |
> +------------------------------------------------------------------------+
>
> +------------------------------------------------------------------------+
> | Links | |
> +------------------------------------------------------------------------+
>
> +------------------------------------------------------------------------+
> | 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://ftp.digium.com/pub/asa/ASA-2007-014.pdf. |
> +------------------------------------------------------------------------+
>
> +------------------------------------------------------------------------+
> | Revision History |
> |------------------------------------------------------------------------|
> | Date | Editor | Revisions Made |
> |-------------------+-------------------------+--------------------------|
> | July 17, 2007 | russell at digium.com | Initial Release |
> +------------------------------------------------------------------------+
>
> Asterisk Project Security Advisory - ASA-2007-014
> Copyright (c) 2007 Digium, Inc. All Rights Reserved.
> Permission is hereby granted to distribute and publish this advisory in its
> original, unaltered form.
>
>
>
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