CVE-2009-1598 in Chrome
Summary
by MITRE
Google Chrome 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 • 04/25/2017
This vulnerability represents a sophisticated cross-origin scripting issue that exploits the interaction between Google Chrome's rendering engine and Adobe Acrobat's JavaScript execution environment within embedded PDF content. The flaw occurs when a malicious PDF file contains a form element with a submit button that references a javascript: URI in its target attribute, allowing the browser to execute JavaScript code from within the PDF context. This creates a dangerous privilege escalation scenario where untrusted PDF content can potentially bypass Adobe Acrobat's built-in security restrictions designed to prevent access to the document object. The vulnerability specifically leverages the shared document.domain relationship that exists between a web application and embedded PDF content, enabling attackers to execute code with elevated privileges that would normally be restricted. The technical exploitation requires a malicious PDF file to be uploaded to a web application that accepts such files, creating a persistent threat vector that can be triggered when users view the compromised PDF.
The core technical flaw resides in Chrome's improper handling of DOM execution contexts when processing javascript: URIs within PDF form elements. This issue stems from a lack of proper security boundary enforcement between the web application's security context and the embedded PDF's Acrobat JavaScript environment. When Chrome processes the target attribute of a submit element within an inline PDF, it fails to maintain the appropriate security isolation that should prevent the javascript: URI from accessing the document object in ways that circumvent Adobe's intended JavaScript restrictions. This behavior violates the fundamental security principle of maintaining distinct execution contexts for different content types and allows for potential cross-site scripting attacks that can leverage the trust relationship between the web application and the PDF viewer. The vulnerability is classified under CWE-264, which addresses permissions, privileges, and access control issues, specifically in the context of improper privilege management.
The operational impact of this vulnerability extends far beyond simple script execution, as it enables attackers to perform sophisticated attacks against web applications that accept PDF uploads from untrusted users. This creates a persistent threat vector where malicious actors can upload PDF files containing the exploit code, which then becomes active when legitimate users view the documents. The attack chain typically involves a web application with permissive file upload policies, allowing attackers to gain a foothold that can later be exploited to access sensitive user data, perform unauthorized actions, or escalate privileges within the application. The shared document.domain relationship provides the necessary bridge for the exploit to work, as it allows the javascript: URI to access the parent document's object model while maintaining the security context that would normally prevent such access. This vulnerability effectively undermines the security model of both the web application and the PDF viewer, creating a dangerous intersection of trust boundaries that can be exploited for privilege escalation attacks.
Mitigation strategies for this vulnerability require a multi-layered approach focusing on both application-level defenses and browser security hardening. Organizations should implement strict file upload validation policies that reject PDF files from untrusted sources and employ content security policies that prevent the execution of javascript: URIs within PDF contexts. Browser security configurations should be enhanced to enforce stricter isolation between different content types, particularly when processing inline PDF content. Additionally, the use of sandboxing mechanisms and privilege separation techniques can help prevent the escalation of privileges that occurs when the javascript: URI accesses the document object. Security professionals should also consider implementing web application firewalls that can detect and block suspicious PDF file patterns, as well as regular security assessments that specifically test for cross-origin scripting vulnerabilities in applications that handle PDF uploads. The remediation process should include updating both Chrome browser versions and Adobe Acrobat software to versions that address the specific privilege escalation issue, while also implementing proper input validation and output encoding to prevent exploitation of similar vulnerabilities in the future. This vulnerability demonstrates the critical importance of maintaining proper security boundaries between different content execution environments, particularly when dealing with active content such as PDF files that can contain embedded scripting capabilities.