CVE-2025-40778 y CVE-2025-40780: Vulnerabilidades de envenenamiento de caché en BIND 9

Ruslan Mikhalov Chief of Threat Research at SOC Prime

CVE-2025-40778 y CVE-2025-40780: Vulnerabilidades de envenenamiento de caché en BIND 9

Detection stack

AIDR
Alert
ETL
Query

Informe de Amenazas
Detecciones
Simulaciones

Análisis

CVE-2025-40778 y CVE-2025-40780 son vulnerabilidades de envenenamiento de caché de alta gravedad en BIND 9, el servidor DNS más implementado en el mundo, utilizado por ISP, empresas y redes gubernamentales. El 22 de octubre de 2025, ISC reveló tres fallas explotables remotamente en BIND 9: CVE-2025-40778, CVE-2025-40780 (ambos CVSS 8.6) y CVE-2025-8677 (CVSS 7.5), todos accesibles a través de la red sin autenticación. CVE-2025-40778 surge del manejo excesivamente permisivo de registros de recursos no solicitados, lo que permite a los resolutores recursivos almacenar en caché datos que violan las reglas de bailía y habilita el envenenamiento de caché que redirige a los usuarios a una infraestructura controlada por el atacante. CVE-2025-40780 debilita la aleatorización del puerto de origen y el ID de consulta, facilitando a los atacantes predecir valores y «ganar» respuestas falsificadas en tránsito. CVE-2025-8677 complementa estos problemas al abusar de registros DNSKEY mal formados para aumentar el uso de la CPU al 100%, creando condiciones de DoS que amplifican las campañas de envenenamiento de caché.

Investigación

La investigación de CVE-2025-40778, CVE-2025-40780 y CVE-2025-8677 debe comenzar con un inventario completo de su infraestructura DNS. Identifique cada resolutor recursivo BIND 9, incluidas instancias internas, de laboratorio y «olvidadas», y asigne cada servidor a su versión y función exactas de BIND (recursivo, autoritativo, reenviador, de validación). Según ISC, las implementaciones afectadas deben actualizarse a 9.18.41, 9.20.15 o 9.21.14 (o Preview 9.18.41-S1 / 9.20.15-S1). Para CVE-2025-40778, busque señales de envenenamiento de caché: registros en caché para nombres nunca consultados, registros adicionales inesperados o cambios repentinos de IP para dominios de alto valor sin actualizaciones planificadas de DNS. Para CVE-2025-40780, busque abuso de entropía: ráfagas de respuestas falsificadas o repetidas de IP no confiables, grandes volúmenes de consultas similares, y advertencias de TLS o navegador en el lado del cliente. Debido a que CVE-2025-8677 puede desencadenar DoS, monitoree búsquedas repetidas de SERVFAIL/tiempos de espera, zonas DNSSEC inusuales y picos de CPU o latencia vinculados a consultas específicas.

Mitigación

Para CVE-2025-40778, CVE-2025-40780 y CVE-2025-8677, ISC enumera no hay soluciones alternativas — parchear BIND 9 es la defensa principal. Los resolutores recursivos deben actualizarse a 9.18.41, 9.20.15 o 9.21.14, o a versiones Preview 9.18.41-S1 / 9.20.15-S1, verificando que los paquetes de la distribución coincidan con la guía de ISC. Al mismo tiempo, fortalezca la configuración del resolutor restringiendo la recurrencia a clientes de confianza y redes internas, evitando resolutores abiertos en Internet y aplicando una verificación estricta de bailía con una aceptación mínima de registros adicionales. Active la validación DNSSEC en resolutores recursivos, supervise las tasas de fallo para detectar señales de manipulación y añada controles a nivel de red para filtrar y limitar el tráfico DNS sospechoso o la actividad de resolutores deshonestos. Finalmente, mejore el monitoreo con alertas en cambios repentinos de IP para dominios críticos, picos en SERVFAIL/tiempos de espera, consultas repetidas o anomalías en el manejo de DNSKEY que puedan indicar la explotación de CVE-2025-8677.

Respuesta

Si sospecha que su infraestructura DNS ha sido objetivo o comprometida, posiblemente a través de CVE-2025-40778, CVE-2025-40780 o CVE-2025-8677, comience por estabilizar y proteger los servicios DNS. Cuando sea posible, falle hacia resolutores secundarios parcheados y restrinja el acceso externo a aquellos vulnerables mientras los mantiene accesibles internamente para análisis. Vacíe las cachés de los resolutores para eliminar entradas envenenadas y verifique registros para zonas internas de alto valor con fuentes autoritativas antes de reutilizarlas. Valide la integridad del DNS verificando resoluciones IP y el estado DNSSEC para dominios críticos (IdPs, correo electrónico, VPN, portales de administración, pagos) contra registradores y registros de cambios. Preserve registros de BIND, registros del sistema y capturas de paquetes para revisión forense, buscando evidencia de redirección a sitios de phishing, portales SSO falsos o servidores de correo no autorizados. Después de aplicar parches, redespliegue con configuraciones fortalecidas, detecciones SIEM actualizadas y brinde información a sus equipos sobre riesgos de envenenamiento de caché DNS y nuevas medidas de seguridad.

Reglas de Detección

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Notifícame

Instrucciones de Carga Útil

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Únase Gratis

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.