#VU29577 Improper access control in PowerDNS Recursor - CVE-2020-14196

Vulnerability identifier: #VU29577

Vulnerability risk: Medium

CVSSv4.0: 2.9 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/U:Green]

CVE-ID: CVE-2020-14196

CWE-ID: CWE-284

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
PowerDNS Recursor
Server applications / DNS servers

Vendor: PowerDNS.COM B.V.

Description

The vulnerability allows a remote attacker to gain unauthorized access to otherwise restricted functionality.

The vulnerability exists due to  ACL applied to the internal web server via "webserver-allow-from" is not properly enforced. A remote attacker can send HTTP queries to the internal web server, bypassing the restriction.

Successful exploitation of the vulnerability requires that the the API webserver is enabled (not the default value).

Mitigation
Install updates from vendor's website.

Vulnerable software versions

PowerDNS Recursor: 4.1.0 rc1 - 4.1.16, 4.2.0 alpha1 - 4.2.2, 4.3.0 rc1 - 4.3.1

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External links
https://doc.powerdns.com/recursor/security-advisories/powerdns-advisory-2020-04.html
https://www.openwall.com/lists/oss-security/2020/07/01/1

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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. However, proof of concept for this vulnerability is available.