In res/res_rtp_asterisk.c in Asterisk 11.x before 11.25.2, 13.x before 13.17.1, and 14.x before 14.6.1 and Certified Asterisk 11.x before 11.6-cert17 and 13.x before 13.13-cert5, unauthorized data disclosure (media takeover in the RTP stack) is possible with careful timing by an attacker. The "strictrtp" option in rtp.conf enables a feature of the RTP stack that learns the source address of media for a session and drops any packets that do not originate from the expected address. This option is enabled by default in Asterisk 11 and above. The "nat" and "rtp_symmetric" options (for chan_sip and chan_pjsip, respectively) enable symmetric RTP support in the RTP stack. This uses the source address of incoming media as the target address of any sent media. This option is not enabled by default, but is commonly enabled to handle devices behind NAT. A change was made to the strict RTP support in the RTP stack to better tolerate late media when a reinvite occurs. When combined with the symmetric RTP support, this introduced an avenue where media could be hijacked. Instead of only learning a new address when expected, the new code allowed a new source address to be learned at all times. If a flood of RTP traffic was received, the strict RTP support would allow the new address to provide media, and (with symmetric RTP enabled) outgoing traffic would be sent to this new address, allowing the media to be hijacked. Provided the attacker continued to send traffic, they would continue to receive traffic as well.

The remote host is affected by the vulnerability described in GLSA-201710-29 (Asterisk: Multiple vulnerabilities)

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

    A remote attacker could execute arbitrary code, cause a denial of       service condition, or cause an unauthorized data disclosure by enticing a       user to run malicious code.
  Workaround :

    There is no known workaround at this time.

According to its SIP banner, the version of Asterisk running on the remote host is 11.x prior to 11.25.3, 13.x prior to 13.17.2, 14.x prior to 14.6.2, 11.6 prior to 11.6-cert18, or 13.13 prior to 13.13-cert6. It is therefore, affected by an information disclosure vulnerability due to insufficient RTCP packet validation. A remote attacker could potentially read buffer contents and redirect where the next RTCP report goes.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The Asterisk project reports :

This is a follow up advisory to AST-2017-005.

Insufficient RTCP packet validation could allow reading stale buffer contents and when combined with the 'nat' and 'symmetric_rtp' options allow redirecting where Asterisk sends the next RTCP report.

The RTP stream qualification to learn the source address of media always accepted the first RTP packet as the new source and allowed what AST-2017-005 was mitigating. The intent was to qualify a series of packets before accepting the new source address.

The RTP/RTCP stack will now validate RTCP packets before processing them.

According to its SIP banner, the version of Asterisk running on the remote host is 11.x prior to 11.25.2, 13.x prior to 13.17.1, 14.x prior to 14.6.1, 11.6 prior to 11.6-cert17, or 13.13 prior to 13.13-cert5. It is therefore, affected by multiple vulnerabilities as described in AST-2017-005, AST-2017-006, and AST-2017-007.

Note for AST-2017-005, only 11.4.0 is affected in the 11.x branch.

Also note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The Asterisk project reports :

AST-2017-005 - A change was made to the strict RTP support in the RTP stack to better tolerate late media when a reinvite occurs. When combined with the symmetric RTP support this introduced an avenue where media could be hijacked. Instead of only learning a new address when expected the new code allowed a new source address to be learned at all times.

AST-2017-006 - The app_minivm module has an 'externnotify' program configuration option that is executed by the MinivmNotify dialplan application. The application uses the caller-id name and number as part of a built string passed to the OS shell for interpretation and execution. Since the caller-id name and number can come from an untrusted source, a crafted caller-id name or number allows an arbitrary shell command injection.

Multiple vulnerabilities have been discovered in Asterisk, an open source PBX and telephony toolkit, which may result in disclosure of RTP connections or the execution of arbitrary shell commands.

For additional information please refer to the upstream advisories:
http://downloads.asterisk.org/pub/security/AST-2017-005.html, http://downloads.asterisk.org/pub/security/AST-2017-006.html

ID	Name	Product	Family	Severity
104230	GLSA-201710-29 : Asterisk: Multiple vulnerabilities	Nessus	Gentoo Local Security Checks	critical
104042	Asterisk 11.x < 11.25.3 / 13.x < 13.17.2 / 14.x < 14.6.2 / 11.6 < 11.6-cert18 / 13.13 < 13.13-cert6 RTP/RTCP information leak (AST-2017-008)	Nessus	Misc.	high
103346	FreeBSD : asterisk -- RTP/RTCP information leak (c2ea3b31-9d75-11e7-bb13-001999f8d30b)	Nessus	FreeBSD Local Security Checks	high
102958	Asterisk 11.x < 11.25.2 / 11.6 < 11.6-cert17 / 13.x < 13.17.1 / 14.x < 14.6.1 / 13.13 < 13.13-cert5 Multiple Vulnerabilities (AST-2017-005 - AST-2017-007)	Nessus	Misc.	critical
102940	FreeBSD : asterisk -- Unauthorized data disclosure and shell access command injection in app_minivm (c599f95c-8ee5-11e7-8be8-001999f8d30b)	Nessus	FreeBSD Local Security Checks	critical
102931	Debian DSA-3964-1 : asterisk - security update	Nessus	Debian Local Security Checks	critical

Detections

Analytics

CVE-2017-14099

high

Tenable Plugins

critical

high

high

critical

critical

critical