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Product Affected

These issues can affect any SRX, vSRX and J-Series with DNS Proxy server enabled.

Severity

High

Severity Assessment (CVSS) Score

7.5 (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)

Problem

ISC BIND software included with Junos OS on SRX, vSRX and J-Series devices has been upgraded to resolve the following vulnerabilities:

CVE	CVSS base score	Summary
CVE-2016-2776	7.5 (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)	buffer.c in named in ISC BIND does not properly construct responses, which allows remote attackers to cause a denial of service (assertion failure and daemon exit) via a crafted query.
CVE-2016-8864	7.5 (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)	named in ISC BIND allows remote attackers to cause a denial of service (assertion failure and daemon exit) via a DNAME record in the answer section of a response to a recursive query, related to db.c and resolver.c.
CVE-2016-9131	7.5 (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)	named in ISC BIND allows remote attackers to cause a denial of service (assertion failure and daemon exit) via a malformed response to an RTYPE ANY query.
CVE-2016-9147	7.5 (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)	named in ISC BIND allows remote attackers to cause a denial of service (assertion failure and daemon exit) via a response containing an inconsistency among the DNSSEC-related RRsets.
CVE-2016-9444	7.5 (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)	named in ISC BIND 9.x before 9.9.9-P5, 9.10.x before 9.10.4-P5, and 9.11.x before 9.11.0-P2 allows remote attackers to cause a denial of service (assertion failure and daemon exit) via a crafted DS resource record in an answer.

These issues only affect devices where DNS proxy service is enabled.

DNS proxy feature is disabled by default.

Juniper SIRT is not aware of any malicious exploitation of these vulnerabilities on Juniper products.

Solution

CVE-2016-2776 has been addressed in Junos OS 12.1X46-D65, 12.3X48-D45, 15.1X49-D70, and all subsequent releases.

CVE-2016-8864 has been addressed in Junos OS 12.3X48-D60, 15.1X49-D120, 17.3R2, 17.4R1 , and all subsequent releases.

CVE-2016-9131, CVE-2016-9147 and CVE-2016-9444 have been addressed in Junos OS 12.1X46-D66, 12.3X48-D50, 15.1X49-D80 , and all subsequent releases.

This issues are being tracked as PR 1219438, 1228678, 1245686, and 1307435, and are visible on the Customer Support website.

How to obtain fixed software:

Security vulnerabilities in Junos are fixed in the next available Maintenance Release of each supported Junos version. In some cases, a Maintenance Release is not planned to be available in an appropriate time-frame. For these cases, Service Releases are made available in order to be more timely. Security Advisory and Security Notices will indicate which Maintenance and Service Releases contain fixes for the issues described. Upon request to JTAC , customers will be provided download instructions for a Service Release. Although Juniper does not provide formal Release Note documentation for a Service Release, a list of "PRs fixed" can be provided on request.

Workaround

DNS proxy service may be disabled to workaround all these issues.

You may view the status of DNS proxy service via the command:

  show system services dns-proxy statistics 
...
DNS proxy statistics        :
    Status            		: enabled
...

Accepting DNS queries only from trusted network would mitigate CVE-2016-2776 which requires a malicious client side request to trigger the named crash.

Firewall filters limiting receipt of DNS queries on TCP and UDP port 53 can be implemented for different hosted groups of DNS servers; external DNS servers should be separate from internal DNS servers. External DNS servers should only accept DNS queries from internal DNS servers and reject externally facing DNS queries if using BIND.

A layered approach utilizing non-BIND based DNS servers may be taken as well; non-BIND servers can be deployed for externally hosted domains, and servers using BIND can be deployed internally.

In addition to the recommendations listed above, it is a good security practice to limit the exploitable attack surface of critical infrastructure networking equipment. Use access lists or firewall filters to limit access to the devices only from trusted, administrative networks or hosts.

Severity Assessment

Information for how Juniper Networks uses CVSS can be found at KB 16446 [juniper.net] "Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories."

Modification History