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2017-04 Security Bulletin: SRX, vSRX and J-Series: Multiple vulnerabilities in ISC BIND named.

  [JSA10785] Show Article Properties


Product Affected:
These issues can affect any SRX, vSRX and J-Series with DNS Proxy server enabled.
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 and CVE-2016-8864 have been addressed in Junos OS 12.1X46-D65, 12.3X48-D45, 15.1X49-D70 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 and 1245686 and are visible on the Customer Support website.
 
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.
 
Modification History:
2017-04-12: Initial release.
 
Related Links:
CVSS Score:
7.5 (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
Risk Level:
High
Risk Assessment:
Information for how Juniper Networks uses CVSS can be found at KB 16446 "Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories."