Resource exhaustion in Nic Knot DNS

1) Resource exhaustion

EUVDB-ID: #VU39670

Risk: High

CVSSv4.0: 6.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber]

CVE-ID: CVE-2016-6171

CWE-ID: CWE-400 - Resource exhaustion

Exploit availability: No

Description

The vulnerability allows a remote non-authenticated attacker to a crash the entire system.

Knot DNS before 2.3.0 allows remote DNS servers to cause a denial of service (memory exhaustion and slave server crash) via a large zone transfer for (1) DDNS, (2) AXFR, or (3) IXFR.

Mitigation

Install update from vendor's website.

Vulnerable software versions

Knot DNS: 2.0.0 - 2.2.1

CPE2.3

• cpe:2.3:a:nic:knot_dns:2.0.0:*:*:*:*:*:*:*
• cpe:2.3:a:nic:knot_dns:2.0.1:*:*:*:*:*:*:*
• cpe:2.3:a:nic:knot_dns:2.0.2:*:*:*:*:*:*:*

External links

https://www.openwall.com/lists/oss-security/2016/07/06/3
https://www.openwall.com/lists/oss-security/2016/07/06/4
https://www.securityfocus.com/bid/91678
https://github.com/sischkg/xfer-limit/blob/master/README.md
https://gitlab.labs.nic.cz/labs/knot/blob/c546a70563ef4c7badb7cb5bdf6d1ba8e7adae82/NEWS
https://gitlab.labs.nic.cz/labs/knot/issues/464
https://lists.dns-oarc.net/pipermail/dns-operations/2016-July/015058.html

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

How the attacker can exploit this vulnerability?

The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.