CVE-2020-25684

A flaw was found in dnsmasq before version 2.83. When getting a reply from a forwarded query, dnsmasq checks in the forward.c:reply_query() if the reply destination address/port is used by the pending forwarded queries. However, it does not use the address/port to retrieve the exact forwarded query, substantially reducing the number of attempts an attacker on the network would have to perform to forge a reply and get it accepted by dnsmasq. This issue contrasts with RFC5452, which specifies a query's attributes that all must be used to match a reply. This flaw allows an attacker to perform a DNS Cache Poisoning attack. If chained with CVE-2020-25685 or CVE-2020-25686, the attack complexity of a successful attack is reduced. The highest threat from this vulnerability is to data integrity.

A flaw was found in dnsmasq before version 2.83. When getting a reply from a forwarded query, dnsmasq checks in the forward.c:reply_query() if the reply destination address/port is used by the pending forwarded queries. However, it does not use the address/port to retrieve the exact forwarded query, substantially reducing the number of attempts an attacker on the network would have to perform to forge a reply and get it accepted by dnsmasq. This issue contrasts with RFC5452, which specifies a query's attributes that all must be used to match a reply. This flaw allows an attacker to perform a DNS Cache Poisoning attack. If chained with CVE-2020-25685 or CVE-2020-25686, the attack complexity of a successful attack is reduced. The highest threat from this vulnerability is to data integrity.

Se encontró un fallo en dnsmasq versiones anteriores a 2.83. Al obtener una respuesta de una consulta reenviada, dnsmasq comprueba en forward.c:reply_query() si la dirección y puerto de destino de la respuesta es utilizado por las consultas reenviadas pendientes. Sin embargo, no usa la dirección y puerto para recuperar la consulta reenviada exacta, lo que reduce sustancialmente la cantidad de intentos que un atacante en la red tendría que realizar para falsificar una respuesta y lograr que dnsmasq la acepte. Este problema contrasta con RFC5452, que especifica los atributos de una consulta que deben ser usados para hacer coincidir una respuesta. Este fallo permite a un atacante realizar un ataque de envenenamiento de caché de DNS. Si está encadenado con CVE-2020-25685 o CVE-2020-25686, se reduce la complejidad del ataque de un ataque con éxito. La mayor amenaza de esta vulnerabilidad es la integridad de los datos