SB2020051922 - DNS amplification attack in Knot Resolver
Published: May 19, 2020 Updated: June 25, 2020
Security Bulletin ID
SB2020051922
Severity
Medium
Patch available
YES
Number of vulnerabilities
1
Exploitation vector
Remote access
Highest impact
Denial of service
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 security vulnerability.
1) Resource exhaustion (CVE-ID: CVE-2020-12667)
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".
Remediation
Install update from vendor's website.
References
- http://cyber-security-group.cs.tau.ac.il/#
- http://www.openwall.com/lists/oss-security/2020/05/19/2
- https://en.blog.nic.cz/2020/05/19/nxnsattack-upgrade-resolvers-to-stop-new-kind-of-random-subdomain-attack/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/76Y4FITMOH6RVPWAANGV7NB2ZHPJJGDQ/
- https://www.knot-resolver.cz/2020-05-19-knot-resolver-5.1.1.html