CVE-2018-5738
Some versions of BIND can improperly permit recursive query service to unauthorized clients
CVSS 5.3 MEDIUMEPSS 11.1%
Em resumo
Servidores DNS BIND podem permitir acidentalmente que qualquer cliente na internet faça consultas recursivas quando deveriam permitir apenas clientes confiáveis. Isso acontece devido a um erro de configuração introduzido no final de 2017, expondo potencialmente o servidor a abuso e ataques.
Detalhe técnico
Uma regressão na análise de configuração do BIND faz com que a configuração 'allow-recursion' herde incorretamente padrões permissivos de 'allow-query' quando nenhuma lista de correspondência explícita é configurada, permitindo consultas recursivas não autorizadas de todos os hosts. A vulnerabilidade afeta versões 9.9.12, 9.10.7, 9.11.x, 9.12.0-P2 e 9.13.0 do BIND quando a recursão está ativada e allow-query-cache/allow-query carecem de valores explícitos, resultando em vetores de amplificação DNS e envenenamento de cache.
Resumo gerado e traduzido por IA a partir da descrição 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