CVE-2018-5738
Some versions of BIND can improperly permit recursive query service to unauthorized clients
CVSS 5.3 MEDIUMEPSS 11.1%
En resumen
Los servidores DNS BIND pueden permitir accidentalmente que cualquier cliente en internet realice consultas recursivas cuando solo deberían permitir clientes de confianza. Esto ocurre por un error de configuración introducido a finales de 2017, exponiendo potencialmente el servidor a abuso y ataques.
Detalle técnico
Una regresión en el análisis de configuración de BIND causa que la configuración 'allow-recursion' herede incorrectamente valores permisivos de 'allow-query' cuando no se establecen listas de coincidencia explícitas, permitiendo consultas recursivas no autorizadas desde todos los hosts. La vulnerabilidad afecta versiones 9.9.12, 9.10.7, 9.11.x, 9.12.0-P2 y 9.13.0 de BIND cuando la recursión está habilitada y allow-query-cache/allow-query carecen de valores explícitos, resultando en vectores de amplificación DNS y envenenamiento de caché.
Resumen generado y traducido por IA a partir de la descripción oficial.
Change #4777 (introduced in October 2017) introduced an unforeseen issue in releases which were issued after that date, affecting which clients are permitted to make recursive queries to a BIND nameserver. The intended (and documented) behavior is that if an operator has not specified a value for the "allow-recursion" setting, it SHOULD default to one of the following: none, if "recursion no;" is set in named.conf; a value inherited from the "allow-query-cache" or "allow-query" settings IF "recursion yes;" (the default for that setting) AND match lists are explicitly set for "allow-query-cache" or "allow-query" (see the BIND9 Administrative Reference Manual section 6.2 for more details); or the intended default of "allow-recursion {localhost; localnets;};" if "recursion yes;" is in effect and no values are explicitly set for "allow-query-cache" or "allow-query". However, because of the regression introduced by change #4777, it is possible when "recursion yes;" is in effect and no match list values are provided for "allow-query-cache" or "allow-query" for the setting of "allow-recursion" to inherit a setting of all hosts from the "allow-query" setting default, improperly permitting recursion to all clients. Affects BIND 9.9.12, 9.10.7, 9.11.3, 9.12.0->9.12.1-P2, the development release 9.13.0, and also releases 9.9.12-S1, 9.10.7-S1, 9.11.3-S1, and 9.11.3-S2 from BIND 9 Supported Preview Edition.
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N