Allele Security Alert
Record smuggling when adding ECS or XPF
PowerDNS DNSDist up to and including 1.3.2
PowerDNS DNSDist 1.3.3
Proof of concept
An issue has been found in PowerDNS DNSDist allowing a remote attacker to craft a DNS query with trailing data such that the addition of a record by dnsdist, for example an OPT record when adding EDNS Client Subnet, might result in the trailing data being smuggled to the backend as a valid record while not seen by dnsdist. This is an issue when dnsdist is deployed as a DNS Firewall and used to filter some records that should not be received by the backend. This issue occurs only when either the ‘useClientSubnet’ or the experimental ‘addXPF’ parameters are used when declaring a new backend.
PowerDNS Security Advisory for dnsdist 2018-08: Record smuggling when adding ECS or XPF
PowerDNS Security Advisories for dnsdist 2018-08
If there is any error in this alert or you wish a comprehensive analysis, let us know.
Last modified: November 8, 2018