8.6 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
8.4 High
AI Score
Confidence
High
5 Medium
CVSS2
Access Vector
NETWORK
Access Complexity
LOW
Authentication
NONE
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
PARTIAL
AV:N/AC:L/Au:N/C:N/I:N/A:P
0.023 Low
EPSS
Percentile
88.5%
A malicious actor who intentionally exploits this lack of effective limitation on the number of fetches performed when processing referrals can, through the use of specially crafted referrals, cause a recursing server to issue a very large number of fetches in an attempt to process the referral. This has at least two potential effects: The performance of the recursing server can potentially be degraded by the additional work required to perform these fetches, and the attacker can exploit this behavior to use the recursing server as a reflector in a reflection attack with a high amplification factor. (CVE-2020-8616)
For more information, refer to ISC Security Advisory CVE-2020-8616 and the academic paper, NXNSAttack, prepared by the discoverers and reporters of this vulnerability.
Note: These links take you to resources outside of AskF5, and it is possible that the documents may be removed without our knowledge.
Impact
This vulnerability has at least two potential effects: the performance of the recursing server can potentially be degraded by the additional work required to perform these fetches, and the attacker can exploit this behavior to use the recursing server as a reflector in a reflection attack with a high amplification factor.
An attacker could exploit this vulnerability to generate a large number of communications between the BIG-IP system and the victim’s authoritative DNS server to cause a distributed denial-of-service (DDoS) attack.
8.6 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
8.4 High
AI Score
Confidence
High
5 Medium
CVSS2
Access Vector
NETWORK
Access Complexity
LOW
Authentication
NONE
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
PARTIAL
AV:N/AC:L/Au:N/C:N/I:N/A:P
0.023 Low
EPSS
Percentile
88.5%