CVE-2018-20065 in Chrome
Summary
by MITRE
Handling of URI action in PDFium in Google Chrome prior to 71.0.3578.80 allowed a remote attacker to initiate potentially unsafe navigations without a user gesture via a crafted PDF file.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 04/27/2020
The vulnerability identified as CVE-2018-20065 resides within the PDFium library component of Google Chrome browser, specifically affecting versions prior to 71.0.3578.80. This flaw represents a significant security concern as it enables remote attackers to manipulate browser navigation behavior through maliciously crafted PDF documents. The vulnerability operates by exploiting the improper handling of URI actions within PDF files, creating a pathway for unauthorized web navigation that bypasses normal security restrictions. The technical implementation involves the PDFium rendering engine's insufficient validation of Uniform Resource Identifier actions that occur during PDF document processing, allowing crafted links to execute without proper user interaction requirements.
The core technical flaw manifests when PDF documents contain URI actions that trigger browser navigation events. In vulnerable versions, the PDFium component fails to properly enforce user gesture requirements before executing these navigation actions, effectively allowing malicious PDF files to initiate web requests or redirects without explicit user consent. This behavior creates a vector for phishing attacks, malicious redirection campaigns, and potential exploitation of user trust in PDF documents. The vulnerability specifically targets the browser's security model that normally requires explicit user interaction before initiating navigation to external resources, thereby undermining fundamental web security principles.
From an operational impact perspective, this vulnerability enables attackers to conduct sophisticated social engineering campaigns where users unknowingly navigate to malicious websites simply by opening compromised PDF documents. The remote exploitation capability means attackers can deliver payloads through PDF files distributed via email attachments, compromised websites, or malicious download sources. Users typically trust PDF documents and may not recognize the dangerous navigation behavior until after the malicious action has been executed, making this attack vector particularly effective for credential theft, malware delivery, and other malicious activities. The lack of user gesture requirement creates an automatic execution environment that bypasses normal browser security mechanisms.
Security professionals should note this vulnerability aligns with CWE-732: Incorrect Permission Assignment for Critical Resource and maps to ATT&CK technique T1059.007 for script-based execution. The recommended mitigation involves immediate updating of Google Chrome to version 71.0.3578.80 or later, which implements proper validation of URI actions and enforces user gesture requirements before navigation execution. Organizations should also consider implementing additional security controls such as PDF file scanning, network-level filtering, and user education about the risks of opening untrusted PDF documents. The vulnerability demonstrates the critical importance of validating all external input within browser rendering engines and highlights the need for robust security models that prevent automatic execution of potentially dangerous actions in document viewers.