Beschleunigen Sie Ihre SSE-Reise. Treten Sie Netskope bei RSA bei.

  • Edge-Produkte von Security Service

    Schützen Sie sich vor fortgeschrittenen und cloudfähigen Bedrohungen und schützen Sie Daten über alle Vektoren hinweg.

  • Borderless SD-WAN

    Stellen Sie selbstbewusst sicheren, leistungsstarken Zugriff auf jeden Remote-Benutzer, jedes Gerät, jeden Standort und jede Cloud bereit.

  • Plattform

    Unübertroffene Transparenz und Daten- und Bedrohungsschutz in Echtzeit in der weltweit größten privaten Sicherheits-Cloud.

Netskope wurde 2022 zum Marktführer im Gartner Magic Quadrant™ for SSE Report ernannt

Report abrufen Netskope Produktübersicht
Netskope führend bei SSE in Gartner MQ 2022
Kurze Antwort von Gartner®: Wie wirkt sich die Übernahme von Infiot durch Netskope auf SD-WAN-, SASE- und SSE-Projekte aus?

Report abrufen
Gartner quick answer
Netskope bietet einen modernen Cloud-Security-Stack mit vereinheitlichten Funktionen für Daten- und Bedrohungsschutz sowie sicherem privaten Zugriff.

Erkunden Sie unsere Plattform
Städtische Metropole aus der Vogelperspektive
Steigen Sie auf marktführende Cloud-Security Service mit minimaler Latenz und hoher Zuverlässigkeit um.

Mehr Informationen
Beleuchtete Schnellstraße mit Serpentinen durch die Berge
Verhindern Sie Bedrohungen, die häufig anderen Sicherheitslösungen entgehen, mithilfe eines SSE-Frameworks mit single-pass Architektur

Mehr Informationen
Gewitter über einem Großstadtgebiet
Zero-Trust-Lösungen für SSE- und SASE-Deployments

Mehr Informationen
Bootsfahrt auf dem offenen Meer
Netskope ermöglicht einen sicheren, cloudintelligenten und schnellen Weg zur Einführung von Cloud-Diensten, Apps und Public-Cloud-Infrastrukturen.

Mehr Informationen
Windkraftanlagen entlang einer Klippe
  • Unsere Kunden

    Netskope bedient mehr als 2.000 Kunden weltweit, darunter mehr als 25 der Fortune 100-Unternehmen

  • Kundenlösungen

    Wir sind für Sie da, stehen Ihnen bei jedem Schritt zur Seite und sorgen für Ihren Erfolg mit Netskope.

  • Schulung und Zertifizierung

    Netskope-Schulungen helfen Ihnen ein Experte für Cloud-Sicherheit zu werden.

Wir helfen unseren Kunden, auf alles vorbereitet zu sein

Sehen Sie sich unsere Kunden an
Lächelnde Frau mit Brille schaut aus dem Fenster
Das talentierte und erfahrene Professional Services-Team von Netskope bietet einen präskriptiven Ansatz für Ihre erfolgreiche Implementierung.

Mehr Informationen
Netskope Professional Services
Mit Netskope-Schulungen können Sie Ihre digitale Transformation absichern und das Beste aus Ihrer Cloud, dem Web und Ihren privaten Anwendungen machen.

Mehr Informationen
Gruppe junger Berufstätiger bei der Arbeit
  • Ressourcen

    Erfahren Sie mehr darüber, wie Netskope Ihnen helfen kann, Ihre Reise in die Cloud zu sichern.

  • Blog

    Erfahren Sie, wie Netskope die Sicherheits- und Netzwerktransformation durch Security Service Edge (SSE) ermöglicht.

  • Veranstaltungen& Workshops

    Bleiben Sie den neuesten Sicherheitstrends immer einen Schritt voraus und tauschen Sie sich mit Gleichgesinnten aus

  • Security Defined

    Finden Sie alles was Sie wissen müssen in unserer Cybersicherheits-Enzyklopädie.

Security Visionaries Podcast

Folge 10: Aufbau von Sicherheitsbeziehungen durch Transparenz
In this episode, Mike and Andreas discuss aligning with works councils, forging business relationships through transparency, and embedding security into value streams.

Podcast abspielen
Building Security Relationships Through Transparency
Lesen Sie die neuesten Informationen darüber, wie Netskope die Zero Trust- und SASE-Reise durch Security Service Edge (SSE) -Funktionen ermöglichen kann.

Den Blog lesen
Sonnenaufgang und bewölkter Himmel
Netskope at RSA

Join Netskope at RSA Conference this year and be part of the real conversations on SASE and Zero Trust. Stop by our booth in South Hall, chat with an expert, register for our speaking sessions, and unwind by joining us at one of our events!

Mehr Informationen
RSA logo
Was ist Security Service Edge?

Entdecken Sie die Sicherheitselemente von SASE, die Zukunft des Netzwerks und der Security in der Cloud.

Mehr Informationen
Kreisverkehr mit vier Straßen
  • Unternehmen

    Wir helfen Ihnen, den Herausforderungen der Cloud-, Daten- und Netzwerksicherheit einen Schritt voraus zu sein.

  • Warum Netskope?

    Cloud-Transformation und hybrides Arbeiten haben die Art und Weise verändert, wie Sicherheit umgesetzt werden muss.

  • Unternehmensführung

    Unser Führungsteam ist fest entschlossen, alles zu tun, was nötig ist, damit unsere Kunden erfolgreich sind.

  • Partner

    Unsere Partnerschaften helfen Ihnen, Ihren Weg in die Cloud zu sichern.

Netskope ermöglicht das "neue" Arbeiten

Finde mehr heraus
Kurvige Straße durch ein Waldgebiet
Netskope definiert Cloud-, Daten- und Netzwerksicherheit neu, um Unternehmen dabei zu unterstützen, Zero-Trust-Prinzipien zum Schutz von Daten anzuwenden.

Mehr Informationen
Serpentinenstraße auf einer Klippe
Denker, Architekten, Träumer, Innovatoren. Gemeinsam liefern wir hochmoderne Cloud-Sicherheitslösungen, die unseren Kunden helfen, ihre Daten und Mitarbeiter zu schützen.

Lernen Sie unser Team kennen
Gruppe von Wanderern erklimmt einen verschneiten Berg
Die partnerorientierte Markteinführungsstrategie von Netskope ermöglicht es unseren Partnern, ihr Wachstum und ihre Rentabilität zu maximieren und gleichzeitig die Unternehmenssicherheit an neue Anforderungen anzupassen.

Mehr Informationen
Gruppe junger, lächelnder Berufstätiger mit unterschiedlicher Herkunft

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

Jan 18 2017
Tags
Cloud Best Practices
Cloud Malware
Cloud Security
Cloudphishing
Netskope Threat Protection
Netskope Threat Research Labs
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 is a Security Researcher with innate interest in targeted attacks and malwares using cloud services. He is primarily focusing in identifying new attack vectors and malwares, campaigns and threat actors using ‘cloud as an attack vector.’