chan_sip.c in the SIP channel driver in Asterisk Open Source 1.6.x before 1.6.2.18.1 and 1.8.x before 1.8.4.3 does not properly handle '\0' characters in SIP packets, which allows remote attackers to cause a denial of service (memory corruption) or possibly have unspecified other impact via a crafted packet.

The remote host is affected by the vulnerability described in GLSA-201110-21 (Asterisk: Multiple vulnerabilities)

    Multiple vulnerabilities have been discovered in Asterisk. Please review       the CVE identifiers referenced below for details.
  Impact :

    An unauthenticated remote attacker may execute code with the privileges       of the Asterisk process or cause a Denial of Service.
  Workaround :

    There is no known workaround at this time.

The Asterisk Development Team has announced the final maintenance release of Asterisk, version 1.6.2.19. This release is available for immediate download at http://downloads.asterisk.org/pub/telephony/asterisk/

Please note that Asterisk 1.6.2.19 is the final maintenance release from the 1.6.2 branch. Support for security related issues will continue until April 21, 2012. For more information about support of the various Asterisk branches, see https://wiki.asterisk.org/wiki/display/AST/Asterisk+Versions

The release of Asterisk 1.6.2.19 resolves several issues reported by the community and would have not been possible without your participation. Thank you!

The following is a sample of the issues resolved in this release :

  - Don't broadcast FullyBooted to every AMI connection The     FullyBooted event should not be sent to every AMI     connection every time someone connects via AMI. It     should only be sent to the user who just connected.
    (Closes issue #18168. Reported, patched by FeyFre)

  - Fix thread blocking issue in the sip TCP/TLS     implementation. (Closes issue #18497. Reported by vois.
    Tested by vois, rossbeer, kowalma, Freddi_Fonet. Patched     by dvossel)

  - Don't delay DTMF in core bridge while listening for DTMF     features. (Closes issue #15642, #16625. Reported by     jasonshugart, sharvanek. Tested by globalnetinc, jde.
    Patched by oej, twilson)

  - Fix chan_local crashs in local_fixup() Thanks OEJ for     tracking down the issue and submitting the patch.
    (Closes issue #19053. Reported, patched by oej)

  - Don't offer video to directmedia callee unless caller     offered it as well (Closes issue #19195. Reported,     patched by one47)

Additionally security announcements AST-2011-008, AST-2011-010, and AST-2011-011 have been resolved in this release.

For a full list of changes in this release, please see the ChangeLog :

http://downloads.asterisk.org/pub/telephony/asterisk/ChangeLog-1.6.2.1 9 The Asterisk Development Team has announced the release of Asterisk versions 1.4.41.1, 1.6.2.18.1, and 1.8.4.3, which are security releases.

These releases are available for immediate download at http://downloads.asterisk.org/pub/telephony/asterisk/releases

The release of Asterisk 1.4.41.1, 1.6.2.18, and 1.8.4.3 resolves several issues as outlined below :

  - AST-2011-008: If a remote user sends a SIP packet     containing a null, Asterisk assumes available data     extends past the null to the end of the packet when the     buffer is actually truncated when copied. This causes     SIP header parsing to modify data past the end of the     buffer altering unrelated memory structures. This     vulnerability does not affect TCP/TLS connections. --     Resolved in 1.6.2.18.1 and 1.8.4.3

  - AST-2011-009: A remote user sending a SIP packet     containing a Contact header with a missing left angle     bracket (<) causes Asterisk to access a NULL pointer. --     Resolved in 1.8.4.3

  - AST-2011-010: A memory address was inadvertently     transmitted over the network via IAX2 via an option     control frame and the remote party would try to access     it. -- Resolved in 1.4.41.1, 1.6.2.18.1, and 1.8.4.3

The issues and resolutions are described in the AST-2011-008, AST-2011-009, and AST-2011-010 security advisories.

For more information about the details of these vulnerabilities, please read the security advisories AST-2011-008, AST-2011-009, and AST-2011-010, which were released at the same time as this announcement.

For a full list of changes in the current releases, please see the ChangeLog :

http://downloads.asterisk.org/pub/telephony/asterisk/releases/ChangeLo g-1.4.41.1 http://downloads.asterisk.org/pub/telephony/asterisk/releases/ChangeLo g-1.6.2.18.1 http://downloads.asterisk.org/pub/telephony/asterisk/releases/ChangeLo g-1.8.4.3

Security advisories AST-2011-008, AST-2011-009, and AST-2011-010 are available at :

http://downloads.asterisk.org/pub/security/AST-2011-008.pdf http://downloads.asterisk.org/pub/security/AST-2011-009.pdf http://downloads.asterisk.org/pub/security/AST-2011-010.pdf

Note that Tenable Network Security has extracted the preceding description block directly from the Fedora security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

Paul Belanger reported a vulnerability in Asterisk identified as AST-2011-008(CVE-2011-2529 ) through which an unauthenticated attacker may crash an Asterisk server remotely. A package containing a NULL char causes the SIP header parser to alter unrelated memory structures.

Jared Mauch reported a vulnerability in Asterisk identified as AST-2011-009through which an unauthenticated attacker may crash an Asterisk server remotely. If a user sends a package with a Contact header with a missing left angle bracket (<) the server will crash. A possible workaround is to disable chan_sip.

The vulnerability identified as AST-2011-010(CVE-2011-2535 ) reported about an input validation error in the IAX2 channel driver. An unauthenticated attacker may crash an Asterisk server remotely by sending a crafted option control frame.

According to the version in its SIP banner, the version of Asterisk running on the remote host is potentially affected by multiple denial of service vulnerabilities :

  - If a remote user sends a SIP packet with a NULL,     Asterisk reads data past the NULL even though the     buffer is actually truncated when copied, which     could lead to an application crash. (AST-2011-008)

  - A remote user sending a SIP packet containing a Contact     header with a missing left angle bracket causes Asterisk     to access a NULL pointer, which could cause the     application to crash. (AST-2011-009)

  - A memory address can be inadvertently transmitted over     the network via IAX2 via an option control frame, which     would cause the remote party to try to access it.
    (AST-2011-010)

The version of Asterisk running on the remote host is potentially affected by multiple denial of service vulnerabilities : 

  - If a remote user sends a SIP packet with a null, Asterisk reads data past the null even though the buffer is actually truncated when copied, which could lead to an application crash. (AST-2011-008)

  - A remote user sending a SIP packet containing a Contact header with a missing left angle bracket causes Asterisk to access a null pointer which could cause the application to crash. (AST-2011-009)

  - A memory address can be inadvertently transmitted over the network via IAX2 via an option control frame which would cause the remote party to try to access it. (AST-2011-010)

The Asterisk Development Team reports :

AST-2011-008: If a remote user sends a SIP packet containing a NULL, Asterisk assumes available data extends past the null to the end of the packet when the buffer is actually truncated when copied. This causes SIP header parsing to modify data past the end of the buffer altering unrelated memory structures. This vulnerability does not affect TCP/TLS connections.

AST-2011-009: A remote user sending a SIP packet containing a Contact header with a missing left angle bracket causes Asterisk to access a NULL pointer.

AST-2011-010: A memory address was inadvertently transmitted over the network via IAX2 via an option control frame and the remote party would try to access it.

Possible enumeration of SIP users due to differing authentication responses.

ID	Name	Product	Family	Type	Severity
56625	GLSA-201110-21 : Asterisk: Multiple vulnerabilities	Nessus	Gentoo Local Security Checks	Local	high
55581	Fedora 14 : asterisk-1.6.2.19-1.fc14 (2011-8914)	Nessus	Fedora Local Security Checks	Local	medium
55554	Debian DSA-2276-1 : asterisk - multiple denial of service	Nessus	Debian Local Security Checks	Local	medium
55457	Asterisk Multiple Channel Drivers Denial of Service (AST-2011-008 / AST-2011-009 / AST-2011-010)	Nessus	Denial of Service	Remote	medium
5969	Asterisk Multiple Channel Drivers Denial of Service (AST-2011-008/AST-2011-009/AST-2011-010)	Nessus Network Monitor	Generic		medium
55430	FreeBSD : Asterisk -- multiple vulnerabilities (40544e8c-9f7b-11e0-9bec-6c626dd55a41)	Nessus	FreeBSD Local Security Checks	Local	medium

Detections

Analytics

CVE-2011-2529

critical

Tenable Plugins

high

medium

medium

medium

medium

medium