DNS amplification attack in Knot Resolver



Published: 2020-05-19 | Updated: 2020-06-25
Risk Medium
Patch available YES
Number of vulnerabilities 1
CVE-ID CVE-2020-12667
CWE-ID CWE-400
Exploitation vector Network
Public exploit N/A
Vulnerable software
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Knot Resolver
Server applications / Other server solutions

Vendor Nic

Security Bulletin

This security bulletin contains one medium risk vulnerability.

1) Resource exhaustion

EUVDB-ID: #VU29248

Risk: Medium

CVSSv3.1: 6.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2020-12667

CWE-ID: CWE-400 - Resource exhaustion

Exploit availability: No

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to application does not properly control consumption of internal resources when processing NSDNAME in NS records. A remote attacker can perform traffic amplification via a crafted DNS answer from an attacker-controlled server. This vulnerability is dubbed "NXNSAttack".

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Knot Resolver: 1.0 - 5.1.0

CPE2.3 External links

http://cyber-security-group.cs.tau.ac.il/#
http://www.openwall.com/lists/oss-security/2020/05/19/2
http://en.blog.nic.cz/2020/05/19/nxnsattack-upgrade-resolvers-to-stop-new-kind-of-random-subdomain-attack/
http://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/76Y4FITMOH6RVPWAANGV7NB2ZHPJJGDQ/
http://www.knot-resolver.cz/2020-05-19-knot-resolver-5.1.1.html


Q & A

Can this vulnerability be exploited remotely?

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

Is there known malware, which exploits this vulnerability?

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



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