CVE-2025-40778 e CVE-2025-40780: Vulnerabilidades de Envenenamento de Cache no BIND 9

Ruslan Mikhalov Chief of Threat Research at SOC Prime

CVE-2025-40778 e CVE-2025-40780: Vulnerabilidades de Envenenamento de Cache no BIND 9

Detection stack

AIDR
Alert
ETL
Query

Relatório de Ameaça
Detecções
Simulações

Análise

CVE-2025-40778 e CVE-2025-40780 são vulnerabilidades de envenenamento de cache de alta severidade no BIND 9, o servidor DNS mais amplamente implantado no mundo, usado por ISPs, empresas e redes governamentais. Em 22 de outubro de 2025, a ISC divulgou três falhas exploráveis remotamente no BIND 9: CVE-2025-40778, CVE-2025-40780 (ambos CVSS 8.6) e CVE-2025-8677 (CVSS 7.5), todas acessíveis através da rede sem autenticação. CVE-2025-40778 surge de um manuseio excessivamente permissivo de registros de recursos não solicitados, permitindo que resolvedores recursivos armazenem em cache dados que violam as regras de bailiwick e habilitando envenenamento de cache que redireciona usuários para infraestrutura controlada por atacantes. CVE-2025-40780 enfraquece a randomização de portas de origem e IDs de consulta, tornando mais fácil para atacantes prever valores e “vencer” respostas falsificadas em trânsito. CVE-2025-8677 complementa esses problemas abusando de registros DNSKEY malformados para empurrar o uso da CPU para 100%, criando condições de DoS que amplificam campanhas de envenenamento de cache.

Investigação

A investigação do CVE-2025-40778, CVE-2025-40780, e CVE-2025-8677 deve começar com um inventário completo de sua infraestrutura DNS. Identifique cada resolvedor recursivo BIND 9, incluindo instâncias internas, de laboratório e “esquecidas”, e mapeie cada servidor para sua exata versão BIND e função (recursivo, autorizado, forwarder, validando). De acordo com a ISC, implantações afetadas devem ser atualizadas para 9.18.41, 9.20.15 ou 9.21.14 (ou Preview 9.18.41-S1 / 9.20.15-S1). Para CVE-2025-40778, procure sinais de envenenamento de cache: registros em cache para nomes nunca consultados, registros adicionais inesperados, ou mudanças súbitas de IP para domínios de alto valor sem atualizações de DNS planejadas. Para CVE-2025-40780, busque abuso de entropia: rajadas de respostas falsificadas ou repetidas de IPs não confiáveis, altos volumes de consultas semelhantes e avisos de TLS ou navegador no lado do cliente. Como CVE-2025-8677 pode desencadear DoS, monitore por SERVFAIL/timeouts repetidos, zonas DNSSEC estranhas, e picos de CPU ou latência ligados a consultas específicas.

Mitigação

Para CVE-2025-40778, CVE-2025-40780 e CVE-2025-8677, a ISC lista nenhuma solução alternativa — aplicar patches no BIND 9 é a principal defesa. Resolvedores recursivos devem ser atualizados para 9.18.41, 9.20.15 ou 9.21.14, ou para versões Preview 9.18.41-S1 / 9.20.15-S1, verificando que os pacotes da distribuição correspondam às orientações da ISC. Ao mesmo tempo, endureça a configuração do resolvedor restringindo a recursão a clientes e redes internas confiáveis, evitando resolvedores abertos na internet e aplicando verificações de bailiwick rigorosas com aceitação mínima de registros adicionais. Ative a validação DNSSEC em resolvedores recursivos, monitore taxas de falha para sinais de manipulação e adicione controles de nível de rede para filtrar e limitar as taxas de tráfego DNS suspeito ou atividade de resolvedor não autorizado. Finalmente, melhore o monitoramento com alertas sobre mudanças súbitas de IP para domínios críticos, picos em SERVFAIL/timeouts, consultas repetidas, ou anomalias no manuseio de DNSKEY que possam indicar exploração do CVE-2025-8677.

Resposta

Se você suspeita que sua infraestrutura DNS foi alvo ou comprometida, possivelmente via CVE-2025-40778, CVE-2025-40780 ou CVE-2025-8677, comece estabilizando e protegendo os serviços DNS. Onde possível, faça failover para resolvedores secundários com patches e restrinja acesso externo a aqueles vulneráveis enquanto os mantém acessíveis internamente para análise. Limpe os caches dos resolvedores para remover entradas envenenadas e verifique registros para zonas internas de alto valor com fontes autorizadas antes de reutilizá-los. Valide a integridade do DNS verificando resoluções de IP e status DNSSEC para domínios críticos (IdPs, e-mail, VPN, portais de admin., pagamentos) contra registradores e logs de mudanças. Preserve logs BIND, logs do sistema e capturas de pacotes para revisão forense, procurando evidências de redirecionamento para sites de phishing, portais SSO falsos ou servidores de e-mail não autorizados. Após aplicar patches, redistribua com configs endurecidas, detecções atualizadas em SIEM e informe suas equipes sobre os riscos de envenenamento de cache DNS e novas salvaguardas.

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Name	Descripiton
PHPSESSID	Preserves user session state across page requests. Cookie generated by applications based on the PHP language. This is a general purpose identifier used to maintain user session variables. It is normally a random generated number, how it is used can be specific to the site, but a good example is maintaining a logged-in status for a user between pages.
sp_i	Used to store information about authenticated User.
sp_r	Used to store information about authenticated User.
sp_a	Used to store information about authenticated User.

Name	Descripiton
tuuid	Collects anonymous data related to the user's visits to the website, such as the number of visits, average time spent on the website and what pages have been loaded.
tuuid_last_update	Collects anonymous data related to the user's visits to the website, such as the number of visits, average time spent on the website and what pages have been loaded.
um	Collects anonymous data related to the user's visits to the website, such as the number of visits, average time spent on the website and what pages have been loaded.
umeh	Collects anonymous data related to the user's visits to the website, such as the number of visits, average time spent on the website and what pages have been loaded.
na_sc_x	Used by the social sharing platform AddThis to keep a record of parts of the site that has been visited in order to recommend other parts of the site.
APID	Collects anonymous data related to the user's visits to the website.
IDSYNC	Collects anonymous data related to the user's visits to the website.
_cc_aud	Collects anonymous statistical data related to the user's website visits, such as the number of visits, average time spent on the website and what pages have been loaded. The purpose is to segment the website's users according to factors such as demographics and geographical location, in order to enable media and marketing agencies to structure and understand their target groups to enable customised online advertising.
_cc_cc	Collects anonymous statistical data related to the user's website visits, such as the number of visits, average time spent on the website and what pages have been loaded. The purpose is to segment the website's users according to factors such as demographics and geographical location, in order to enable media and marketing agencies to structure and understand their target groups to enable customised online advertising.
_cc_dc	Collects anonymous statistical data related to the user's website visits, such as the number of visits, average time spent on the website and what pages have been loaded. The purpose is to segment the website's users according to factors such as demographics and geographical location, in order to enable media and marketing agencies to structure and understand their target groups to enable customised online advertising.
_cc_id	Collects anonymous statistical data related to the user's website visits, such as the number of visits, average time spent on the website and what pages have been loaded. The purpose is to segment the website's users according to factors such as demographics and geographical location, in order to enable media and marketing agencies to structure and understand their target groups to enable customised online advertising.
dpm	Via a unique ID that is used for semantic content analysis, the user's navigation on the website is registered and linked to offline data from surveys and similar registrations to display targeted ads.
acs	Collects anonymous data related to the user's visits to the website, such as the number of visits, average time spent on the website and what pages have been loaded, with the purpose of displaying targeted ads.
clid	Collects anonymous data related to the user's visits to the website, such as the number of visits, average time spent on the website and what pages have been loaded, with the purpose of displaying targeted ads.
KRTBCOOKIE_#	Registers a unique ID that identifies the user's device during return visits across websites that use the same ad network. The ID is used to allow targeted ads.
PUBMDCID	Registers a unique ID that identifies the user's device during return visits across websites that use the same ad network. The ID is used to allow targeted ads.
PugT	Registers a unique ID that identifies the user's device during return visits across websites that use the same ad network. The ID is used to allow targeted ads.
ssi	Registers a unique ID that identifies a returning user's device. The ID is used for targeted ads.
_tmid	Registers a unique ID that identifies the user's device upon return visits. The ID is used to target ads in video clips.
wam-sync	Used by the advertising platform Weborama to determine the visitor's interests based on pages visits, content clicked and other actions on the website.
wui	Used by the advertising platform Weborama to determine the visitor's interests based on pages visits, content clicked and other actions on the website.
AFFICHE_W	Used by the advertising platform Weborama to determine the visitor's interests based on pages visits, content clicked and other actions on the website.
B	Collects anonymous data related to the user's website visits, such as the number of visits, average time spent on the website and what pages have been loaded. The registered data is used to categorise the users' interest and demographical profiles with the purpose of customising the website content depending on the visitor.
1P_JAR	These cookies are used to gather website statistics, and track conversion rates.
APISID	Google set a number of cookies on any page that includes a Google reCAPTCHA. While we have no control over the cookies set by Google, they appear to include a mixture of pieces of information to measure the number and behaviour of Google reCAPTCHA users.
HSID	Google set a number of cookies on any page that includes a Google reCAPTCHA. While we have no control over the cookies set by Google, they appear to include a mixture of pieces of information to measure the number and behaviour of Google reCAPTCHA users.
NID	Google set a number of cookies on any page that includes a Google reCAPTCHA. While we have no control over the cookies set by Google, they appear to include a mixture of pieces of information to measure the number and behaviour of Google reCAPTCHA users.
SAPISID	Google set a number of cookies on any page that includes a Google reCAPTCHA. While we have no control over the cookies set by Google, they appear to include a mixture of pieces of information to measure the number and behaviour of Google reCAPTCHA users.
SID	Google set a number of cookies on any page that includes a Google reCAPTCHA. While we have no control over the cookies set by Google, they appear to include a mixture of pieces of information to measure the number and behaviour of Google reCAPTCHA users.
SIDCC	Security cookie to protect users data from unauthorised access.
SSID	Google set a number of cookies on any page that includes a Google reCAPTCHA. While we have no control over the cookies set by Google, they appear to include a mixture of pieces of information to measure the number and behaviour of Google reCAPTCHA users.
__utmx	This cookie is associated with Google Website Optimizer, a tool designed to help site owners improve their wbesites. It is used to distinguish between two varaitions a webpage that might be shown to a visitor as part of an A/B split test. This helps site owners to detemine which version of a page performs better, and therefore helps to improve the website.
__utmxx	This cookie is associated with Google Website Optimizer, a tool designed to help site owners improve their wbesites. It is used to distinguish between two varaitions a webpage that might be shown to a visitor as part of an A/B split test. This helps site owners to detemine which version of a page performs better, and therefore helps to improve the website.

Name	Descripiton
_hjid	Hotjar cookie. This cookie is set when the customer first lands on a page with the Hotjar script. It is used to persist the random user ID, unique to that site on the browser. This ensures that behavior in subsequent visits to the same site will be attributed to the same user ID.
_hjIncludedInSample	This cookie is associated with web analytics functionality and services from Hot Jar, a Malta based company. It uniquely identifies a visitor during a single browser session and indicates they are included in an audience sample.
intercom-id-[xxx]	This cookie is used by Intercom as a session so that users can continue a chat as they move through the site.
intercom-session-[xxx]	Used to keeping track of sessions and remember logins and conversations.
demdex	Via a unique ID that is used for semantic content analysis, the user's navigation on the website is registered and linked to offline data from surveys and similar registrations to display targeted ads.
CookieConsent	Stores the user's cookie consent state for the current domain.
__cfduid	Used by the content network, Cloudflare, to identify trusted web traffic.
ss	These cookies enable the website to provide enhanced functionality and personalisation . They may be set by us or by third party providers whose services we have added to our pages. These services may include the Live Chat facility, Contact Us form(s), the Product Quotation forms and submission process, and the Email Newsletter sign up functionality .

Name	Descripiton
_ga	This cookie name is asssociated with Google Universal Analytics - which is a significant update to Google's more commonly used analytics service. This cookie is used to distinguish unique users by assigning a randomly generated number as a client identifier. It is included in each page. Registers a unique ID that is used to generate statistical data on how the visitor uses the website. request in a site and used to calculate visitor, session and campaign data for the sites analytics reports. By default it is set to expire after 2 years, although this is customisable by website owners.
_gat	Used by Google Analytics to throttle request rate. This cookie name is associated with Google Universal Analytics, according to documentation it is used to throttle the request rate - limiting the collection of data on high traffic sites. It expires after 10 minutes.
_gid	This cookie name is asssociated with Google Universal Analytics. This appears to be a new cookie and as of Spring 2017 no information is available from Google. It appears to store and update a unique value for each page visited. Registers a unique ID that is used to generate statistical data on how the visitor uses the website.
IDE	Used by Google DoubleClick to register and report the website user's actions after viewing or clicking one of the advertiser's ads with the purpose of measuring the efficacy of an ad and to present targeted ads to the user.
r/collect	Used by Google DoubleClick to register and report the website user's actions after viewing or clicking one of the advertiser's ads with the purpose of measuring the efficacy of an ad and to present targeted ads to the user.
test_cookie	Used to check if the user's browser supports cookies.
collect	Used to send data to Google Analytics about the visitor's device and behaviour. Tracks the visitor across devices and marketing channels.
ads/user-lists/#	These cookies may be set through our site by our advertising partners. They may be used by those companies to build a profile of your interests and show you relevant adverts on other sites.
c	Registers anonymised user data, such as IP address, geographical location, visited websites, and what ads the user has clicked, with the purpose of optimising ad display based on the user's movement on websites that use the same ad network.
khaos	Registers anonymised user data, such as IP address, geographical location, visited websites, and what ads the user has clicked, with the purpose of optimising ad display based on the user's movement on websites that use the same ad network.
put_#	Registers anonymised user data, such as IP address, geographical location, visited websites, and what ads the user has clicked, with the purpose of optimising ad display based on the user's movement on websites that use the same ad network.
rpb	Registers anonymised user data, such as IP address, geographical location, visited websites, and what ads the user has clicked, with the purpose of optimising ad display based on the user's movement on websites that use the same ad network.
rpx	Registers anonymised user data, such as IP address, geographical location, visited websites, and what ads the user has clicked, with the purpose of optimising ad display based on the user's movement on websites that use the same ad network.
tap.php	Registers anonymised user data, such as IP address, geographical location, visited websites, and what ads the user has clicked, with the purpose of optimising ad display based on the user's movement on websites that use the same ad network.