¡El futuro de Confianza Cero y SASE es ahora! Ver a la carta

cerrar
cerrar
  • Por qué Netskope chevron

    Cambiar la forma en que las redes y la seguridad trabajan juntas.

  • Nuestros clientes chevron

    Netskope atiende a más de 3.000 clientes en todo el mundo, entre ellos más de 25 de las 100 empresas de Fortune

  • Nuestros Partners chevron

    Nos asociamos con líderes en seguridad para ayudarlo a asegurar su viaje a la nube.

La más Alta en Ejecución. Más Avanzada en Visión.

Netskope ha sido reconocido como Líder en el Gartner® Magic Quadrant™ de 2023 en SSE.

Obtenga el informe
Netskope ha sido reconocido como Líder en el Gartner® Magic Quadrant™ de 2023 en SSE.
Ayudamos a nuestros clientes a estar preparados para cualquier situación

See our customers
Woman smiling with glasses looking out window
La estrategia de venta centrada en el partner de Netskope permite a nuestros canales maximizar su expansión y rentabilidad y, al mismo tiempo, transformar la seguridad de su empresa.

Más información sobre los socios de Netskope
Group of diverse young professionals smiling
Tu red del mañana

Planifique su camino hacia una red más rápida, más segura y más resistente diseñada para las aplicaciones y los usuarios a los que da soporte.

Obtenga el whitepaper
Tu red del mañana
Introducing the Netskope One Platform

Netskope One is a cloud-native platform that offers converged security and networking services to enable your SASE and zero trust transformation.

Learn about Netskope One
Abstract with blue lighting
Adopte una arquitectura de borde de servicio de acceso seguro (SASE)

Netskope NewEdge es la nube privada de seguridad más grande y de mayor rendimiento del mundo y ofrece a los clientes una cobertura de servicio, un rendimiento y una resiliencia incomparables.

Más información sobre NewEdge
NewEdge
Netskope Cloud Exchange

Cloud Exchange (CE) de Netskope ofrece a sus clientes herramientas de integración eficaces para que saquen partido a su inversión en estrategias de seguridad.

Más información sobre Cloud Exchange
Vídeo de Netskope
  • Servicio de seguridad Productos Edge chevron

    Protéjase contra las amenazas avanzadas y en la nube y salvaguarde los datos en todos los vectores.

  • Borderless SD-WAN chevron

    Proporcione con confianza un acceso seguro y de alto rendimiento a cada usuario remoto, dispositivo, sitio y nube.

  • Secure Access Service Edge chevron

    Netskope SASE proporciona una solución SASE nativa en la nube, totalmente convergente y de un único proveedor.

La plataforma del futuro es Netskope

Intelligent Security Service Edge (SSE), Cloud Access Security Broker (CASB), Cloud Firewall, Next Generation Secure Web Gateway (SWG) y Private Access for ZTNA integrados de forma nativa en una única solución para ayudar a todas las empresas en su camino hacia el Servicio de acceso seguro Arquitectura perimetral (SASE).

Todos los productos
Vídeo de Netskope
Next Gen SASE Branch es híbrida: conectada, segura y automatizada

Netskope Next Gen SASE Branch converge Context-Aware SASE Fabric, Zero-Trust Hybrid Security y SkopeAI-Powered Cloud Orchestrator en una oferta de nube unificada, marcando el comienzo de una experiencia de sucursal completamente modernizada para la empresa sin fronteras.

Obtenga más información sobre Next Gen SASE Branch
Personas en la oficina de espacios abiertos.
Diseño de una arquitectura SASE para Dummies

Obtenga un ejemplar gratuito del único manual que necesitará sobre diseño de una arquitectura SASE.

Obtenga el eBook
Cambie a los servicios de seguridad en la nube líderes del mercado con una latencia mínima y una alta fiabilidad.

Más información sobre NewEdge
Lighted highway through mountainside switchbacks
Habilite de forma segura el uso de aplicaciones de IA generativa con control de acceso a aplicaciones, capacitación de usuarios en tiempo real y la mejor protección de datos de su clase.

Descubra cómo aseguramos el uso generativo de IA
Habilite de forma segura ChatGPT y IA generativa
Soluciones de confianza cero para implementaciones de SSE y SASE

Más información sobre Confianza Cero
Boat driving through open sea
Netskope logra la alta autorización FedRAMP

Elija Netskope GovCloud para acelerar la transformación de su agencia.

Más información sobre Netskope GovCloud
Netskope GovCloud
  • Recursos chevron

    Obtenga más información sobre cómo Netskope puede ayudarle a proteger su viaje hacia la nube.

  • Blog chevron

    Learn how Netskope enables security and networking transformation through security service edge (SSE)

  • Events and Workshops chevron

    Manténgase a la vanguardia de las últimas tendencias de seguridad y conéctese con sus pares.

  • Seguridad definida chevron

    Todo lo que necesitas saber en nuestra enciclopedia de ciberseguridad.

Podcast Security Visionaries

Elecciones, desinformación y seguridad
Este episodio analiza los aspectos de la seguridad electoral en torno al registro de votantes y los controles físicos en los lugares de votación.

Reproducir el pódcast
Blog: Elecciones, desinformación y seguridad
Últimos blogs

Read how Netskope can enable the Zero Trust and SASE journey through security service edge (SSE) capabilities.

Lea el blog
Sunrise and cloudy sky
SASE Week 2023: ¡Su viaje SASE comienza ahora!

Sesiones de repetición de la cuarta SASE Week.

Explorar sesiones
SASE Week 2023
¿Qué es Security Service Edge (SSE)?

Explore el lado de la seguridad de SASE, el futuro de la red y la protección en la nube.

Más información sobre el servicio de seguridad perimetral
Four-way roundabout
  • Empresa chevron

    Le ayudamos a mantenerse a la vanguardia de los desafíos de seguridad de la nube, los datos y la red.

  • Liderazgo chevron

    Nuestro equipo de liderazgo está firmemente comprometido a hacer todo lo necesario para que nuestros clientes tengan éxito.

  • Soluciones para clientes chevron

    Le apoyamos en cada paso del camino, garantizando su éxito con Netskope.

  • Formación y certificación chevron

    La formación de Netskope le ayudará a convertirse en un experto en seguridad en la nube.

Apoyar la sostenibilidad a través de la seguridad de los datos

Netskope se enorgullece de participar en Vision 2045: una iniciativa destinada a crear conciencia sobre el papel de la industria privada en la sostenibilidad.

Descubra más
Apoyando la sustentabilidad a través de la seguridad de los datos
Pensadores, constructores, soñadores, innovadores. Juntos, ofrecemos soluciones de seguridad en la nube de vanguardia para ayudar a nuestros clientes a proteger sus datos y usuarios.

Conozca a nuestro equipo
Group of hikers scaling a snowy mountain
El talentoso y experimentado equipo de servicios profesionales de Netskope proporciona un enfoque prescriptivo para su exitosa implementación.

Más información sobre servicios profesionales
Servicios profesionales de Netskope
Asegure su viaje de transformación digital y aproveche al máximo sus aplicaciones en la nube, web y privadas con la capacitación de Netskope.

Infórmese sobre Capacitaciones y Certificaciones
Group of young professionals working

Decoys, Phishing, and the Cloud: The Latest Fan-out Effect

Jan 18 2017
Etiquetas
Cloud Best Practices
Cloud Malware
Cloud Security
Cloudphishing
Netskope Threat Protection
Tools and Tips
Vulnerability Advisory

Netskope Threat Research Labs has observed phishing attacks using decoy PDF files, URL redirection, and Cloud Storage services to infect users and propagate malware. Because many organizations have default “allow” security policies for popular Cloud Storage services and PDF readers to let users take advantage of these useful services, these attacks pass through the corporate network to end users’ machines undetected. Moreover, as users collaborate and share through cloud services, these malicious files posing as PDFs “fan out” to shared users, creating a secondary propagation vector. We are calling this the “CloudPhishing Fan-out Effect.”

In this blog, we will detail the insidious nature of CloudPhishing and the secondary fan-out using two recently detected cases. We will also illustrate how an attack – even if unsuccessful – may leave the target vulnerable to future attacks. Additionally, we will outline the Netskope protection stance, and general best practices to handle this attack.

CloudPhishing Fan-out

The CloudPhishing fan-out effect occurs when a victim inadvertently shares the phishing document with colleagues, whether internal or external, via a cloud service. This is particularly insidious in the cloud, as shared users lose the context of the document’s external origin and may trust the internally shared document as if it were created internally. The visual depiction of the attack chain showing the CloudPhishing fan-out is shown in Figure 1.

Figure 1: CloudPhishing fanout effect within shared users in the cloud

One example of this threat is an invoice decoy document named “Invoice_2884.pdf” (MD5 – 987a95d47ea99fe32e4ce095c591383f), which has been shared in Microsoft OneDrive for Business. Other than having the file shared in OneDrive, the SaaS application is unrelated to the attack. This threat, seen in one of our customer environments, is detected by Netskope Active Threat Protection as Backdoor.Phishing.FW.

The decoy PDF is usually delivered as an email attachment named,“invoice” in an attempt to lure the victim into executing the file. When the user opens the PDFdocument and inadvertently clicks the hyperlink in the PDF, the decoy PDF retrieves a phished page referenced by the TinyURL service, as shown in Figure 2.

Figure 2: Visual depiction of the working of the PDF decoy, Invoice_2884.pdf

Analysis of the PDF decoy, Invoice_2884.pdf

On execution of the PDF decoy, “Invoice_2884.pdf,” the victim is presented with a secured PDF online document message, luring him or her to click on the “View On Adobe” hyperlink to view the document, as shown in Figure 3.

Figure 3: Message displayed on opening Invoice_2884.pdf

Upon clicking the “View on Adobe” hyperlink, the victim is displayed with a security warning message from Adobe that the document is trying to connect to the TinyURL redirection service link, as shown in Figure 4.

Figure 4: Invoice_2884.pdf connecting to TinyURL redirection service link

If this action is allowed without un-checking the “Remember this action…,” all future connections to TinyURL.com will be allowed without any security warning prompts from the victim’s machine, as shown in Figure 5. This, in effect, weakens the security posture of the endpoint against future attacks.

Figure 5: Connection to TinyURL.com set to “Always Allow”

Allowing this action paves a pathway for the attacker to carry out future actions by launching decoys from the allowed domains list.

The decoy PDF connects to the TinyURL link, http://TinyURL[.]com/he9n53x, as shown in Figure 6.

Figure 6: Hyperlink in the PDF decoy, Invoice_2884.pdf

The TinyURL link redirects to the link, http://www.pdf.anothersideofpeace[.]org/PO.htm. The attacker used the TinyURL link as an evasive tactic to hide the original link. At the time of analysis, the web page was down and not serving any content. This might be because the web page was removed or renamed. The web page was also blocked by the Chrome browser, as shown in Figure 7.

Figure 7: Blocked web page by Chrome browser

Similarly-themed PDF decoy strains

We identified similar strains of decoy PDF documents that retrieve phished pages hosted in several URL redirection services and Cloud Storage services. The visual depiction of protection via Netskope Active Threat Protection for the PDF decoy using Cloud Storage services for retrieving the phished pages and the CloudPhishing fan-out effect is shown in Figure 8.

Figure 8: Protection from the CloudPhishing Fan-out effect

Analysis of a Second CloudPhishing PDF decoy using Cloud Storage services

One case of the PDF decoy we observed using Cloud Storage services to deliver a phished page, was compressed in a ZIP archive named “Kindly confirm our inquiry.zip.” The ZIP file contained a PDF document named “Inquirys.PDF,” as shown in Figure 9.

Figure 9: CloudPhising PDF decoy present in the file, “Kindly confirm our inquiry.zip”

The PDF decoy, “Inquirys.PDF,” is detected by Netskope Active Threat Protection as Backdoor.Scm.EX.

Upon execution of the PDF decoy, the victim is presented with a message that the document is highly secured by Adobe and prompted to click on the “DOWNLOAD NOW” hyperlink to view the document, as shown in Figure 10.

Figure 10: Message displayed on execution of PDF decoy, “Inquirys.PDF”

Upon clicking the “DOWNLOAD NOW” hyperlink, the victim is presented with a message that the document is trying to connect to Dropbox, as shown in Figure 11.

Figure 11: “Inquirys.PDF” connecting to Dropbox

As mentioned earlier with the TinyURL redirection service, if this action is allowed without un-checking the “Remember this action…,” all future connections to dropbox.com will be allowed without any security warning prompt from the victim’s machine, as shown in Figure 12.

Figure 12: Connection to dropbox.com set to “Always Allow”

The decoy PDF connects to the Dropbox link, https://www.dropbox[.]com/s/bm0lqz2jf0ya4el/52439765REQ.html?dl=1, as shown in Figure 13.

Figure 13: Hyperlink in the PDF decoy, “Inquirys.PDF”

The download link retrieves a phished login page named “Inquire,h (1).html” to the user’s machine, as shown in Figure 14.

Figure 14: “Inquire,h (1).html” phished login page

The source of the phished page contains a POST action to the website, http://wisdomschool[.]cf/include/encrypted/davidmckiernan7.php, as shown in Figure 15.

Figure 15: Victim’s credentials uploaded to a website

Upon entering the login details in the phished page, the victim’s credentials are uploaded to the attacker’s address, as shown in Figure 16.

Figure 16: Packet capture showing the victim’s credentials being uploaded to a website

Once the credentials are uploaded to the website, the victim is redirected to the original login page, https://login.live.com, and is again asked to enter his or her credentials.

Default Allow Policy in Adobe Acrobat Reader Software

Our analysis showed that the Adobe Acrobat Reader prompts a security warning to the user when the document connects to a link. This feature allows any URL related to the domain that is on the allowed list. Based on the behavior seen in the latest version of the Adobe Acrobat Reader, we recommend users un-check the “Remember this action…” option while allowing the PDF to connect to an external link. We also advise users to hover their mouse over the hyperlink to confirm the link and also regularly monitor managed Internet access settings in the PDF reader’s Trust Manager.

The phishing PDF decoys showcase the use of URL redirectors and cloud services, and also a secondary propagation vector within the shared users leading to the CloudPhishing fan-out. By taking advantage of the “default allow” action in popular PDF readers, the attacker can easily deploy multiple attacks without getting the security warning after the first alert. This makes the attacker effectively a host for phishing pages or malicious payloads using URL redirection services and Cloud Storage services. Netskope has contacted Dropbox to take down the URL hosting the phished page. We will continue to monitor the decoy documents using Cloud Storage services and update our findings on the developments.

General Recommendations

Netskope recommends the following to combat CloudPhishing and malware threats:

  • Detect and remediate all threats at rest in sanctioned cloud services using a threat-aware Cloud Access Security Broker like Netskope
  • Detect and remediate all threats being downloaded from unsanctioned cloud services using a threat-aware solution like Netskope
  • Actively track usage of unsanctioned cloud services and enforce DLP policies to control files and data en route to or from your corporate environment
  • Regularly back up and turn on versioning for critical content in cloud services
  • Enable the “View known file extensions” option on Windows machines
  • Un-check the option “Remember this action for this site for all PDF documents” in the PDF reader software
  • Hover your mouse over all hyperlinks to confirm them before clicking on the link
  • Actively track URL links added to the “Always Allow” list in PDF reader software
  • Avoid executing any file unless you are very sure that they are benign
  • Warn users to avoid opening untrusted attachments regardless of their extensions or file names
  • Keep systems and antivirus updated with the latest releases and patches
author image
Ashwin Vamshi
Ashwin Vamshi es un investigador de seguridad con un interés innato en los ataques dirigidos y el malware que utilizan servicios en la nube. Se centra principalmente en la identificación de nuevos vectores de ataque y malware, campañas y ciber-delincuentes que utilizan la "nube como vector de ataque".

Stay informed!

Subscribe for the latest from the Netskope Blog