CVE-2009-1597 in Firefox
Summary
by MITRE
Mozilla Firefox executes DOM calls in response to a javascript: URI in the target attribute of a submit element within a form contained in an inline PDF file, which might allow remote attackers to bypass intended Adobe Acrobat JavaScript restrictions on accessing the document object, as demonstrated by a web site that permits PDF uploads by untrusted users, and therefore has a shared document.domain between the web site and this javascript: URI. NOTE: the researcher reports that Adobe s position is "a PDF file is active content."
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Analysis
by VulDB Data Team • 12/07/2017
This vulnerability represents a sophisticated cross-domain security issue affecting Mozilla Firefox browsers when processing inline PDF content. The flaw occurs when a malicious PDF file contains a form element with a submit button that has a javascript: URI specified in its target attribute. When users interact with such forms, Firefox executes the javascript code contained within the URI, potentially bypassing Adobe Acrobat's intended JavaScript restrictions. The vulnerability specifically exploits the document.domain sharing mechanism between web sites and embedded PDF content, creating an attack vector that leverages the trust relationship established by shared domains.
The technical execution of this vulnerability relies on the browser's handling of inline PDF content and its interaction with JavaScript execution contexts. When Firefox renders a PDF containing an embedded form, it processes the form elements and their associated JavaScript handlers. The target attribute of submit elements can contain javascript: URIs that should normally be restricted by Adobe's security model, but Firefox's implementation allows these calls to execute with elevated privileges. This behavior stems from the browser's failure to properly isolate the JavaScript execution environment of inline PDF content from the parent web page's security context, creating a privilege escalation scenario.
The operational impact of this vulnerability extends beyond simple script execution, as it enables attackers to manipulate the document object and potentially access sensitive information or perform unauthorized actions within the PDF's security context. The vulnerability is particularly dangerous when combined with PDF upload functionality on web applications, as it allows attackers to craft malicious PDF files that can execute arbitrary code in the context of the victim's browser session. This creates a persistent threat vector that can be exploited through various attack surfaces including email attachments, file upload portals, and web applications that process user-uploaded PDF documents.
The security implications align with CWE-74 and CWE-79 categories, specifically addressing code injection vulnerabilities and cross-site scripting issues in web applications. This vulnerability demonstrates how browser-based security models can be bypassed through improper handling of embedded content types, particularly when different content types share execution contexts. The ATT&CK framework categorizes this under privilege escalation and defense evasion techniques, as attackers can leverage this flaw to execute malicious code with elevated privileges within the browser's security boundaries. Organizations should implement comprehensive mitigations including strict content filtering policies, sandboxed PDF viewing environments, and regular browser updates to address this vulnerability.
The fundamental flaw lies in the browser's insufficient isolation between different content types and their respective security contexts. Adobe's position that "a PDF file is active content" acknowledges the inherent risks of treating PDFs as potentially malicious active content, yet Firefox's implementation fails to properly enforce the security boundaries that should exist between web page content and embedded PDF JavaScript execution. This vulnerability highlights the complexity of modern web security where multiple content types interact within a single browser environment, creating potential attack surfaces that require careful consideration of security boundaries and privilege management. The exploitation scenario requires a combination of user interaction with malicious PDF content and the presence of shared document domains, making it a sophisticated but achievable attack vector for determined adversaries.