PowerDNS Security Advisory 2019-03: Insufficient validation in the HTTP remote backend

• CVE: CVE-2019-3871
• Date: March 18th 2019
• Affects: PowerDNS Authoritative up to and including 4.1.6
• Not affected: 4.1.7, 4.0.7
• Severity: High
• Impact: Denial of Service, Information Disclosure, Content spoofing
• Exploit: This problem can be triggered via crafted queries
• Risk of system compromise: No
• Solution: Upgrade to a non-affected version

An issue has been found in PowerDNS Authoritative Server when the HTTP remote backend is used in RESTful mode (without post=1 set), allowing a remote user to cause the HTTP backend to connect to an attacker-specified host instead of the configured one, via a crafted DNS query. This can be used to cause a denial of service by preventing the remote backend from getting a response, content spoofing if the attacker can time its own query so that subsequent queries will use an attacker-controlled HTTP server instead of the configured one, and possibly information disclosure if the Authoritative Server has access to internal servers.

This issue has been assigned CVE-2019-3871.

PowerDNS Authoritative up to and including 4.1.6 is affected. Please note that at the time of writing, PowerDNS Authoritative 3.4 and below are no longer supported, as described in https://doc.powerdns.com/authoritative/appendices/EOL.html.

We would like to thank Adam Dobrawy, Frederico Silva and Gregory Brzeski from HyperOne.com for finding and subsequently reporting this issue!