CVE-2011-3916 in Chrome
Summary
by MITRE
Google Chrome before 16.0.912.63 does not properly handle PDF cross references, which allows remote attackers to cause a denial of service (out-of-bounds read) via unspecified vectors.
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Analysis
by VulDB Data Team • 11/28/2021
The vulnerability identified as CVE-2011-3916 represents a critical flaw in Google Chrome's PDF rendering engine that existed prior to version 16.0.912.63. This issue stems from improper handling of PDF cross-reference tables, which are essential components used by Adobe Acrobat and other PDF viewers to efficiently navigate and access specific parts of large PDF documents. The flaw manifests when Chrome processes maliciously crafted PDF files that contain malformed cross-reference entries, leading to memory access violations that can result in application crashes or unexpected behavior.
The technical implementation of this vulnerability involves Chrome's internal PDF parser failing to properly validate cross-reference entries before attempting to access memory locations referenced by these entries. Cross-reference tables in PDF files contain pointers to object locations within the file structure, and when these pointers are manipulated to reference memory outside the intended bounds, the parser encounters out-of-bounds read conditions. This type of vulnerability falls under the CWE-125 weakness category, which specifically addresses out-of-bounds read conditions that can lead to information disclosure, application crashes, or potentially more severe consequences depending on the execution context. The vulnerability operates at the intersection of memory safety issues and improper input validation, where the PDF parser fails to implement adequate bounds checking mechanisms.
From an operational perspective, this vulnerability presents a significant risk to users who frequently encounter PDF documents from untrusted sources. Attackers can exploit this weakness by crafting malicious PDF files that, when opened in affected Chrome versions, trigger the out-of-bounds read condition and cause the browser to crash. This creates a reliable denial of service scenario where legitimate users experience interrupted browsing sessions, potentially leading to productivity loss and user frustration. The attack vector is particularly concerning because PDF documents are widely distributed through email attachments, web downloads, and various online platforms, making the attack surface broad and accessible to threat actors with minimal technical expertise.
The impact of this vulnerability extends beyond simple service disruption to potentially enable more sophisticated attacks. While the primary effect is denial of service, the out-of-bounds read condition could potentially be leveraged to extract sensitive information from memory or provide a foothold for more advanced exploitation techniques. Security researchers have noted that such memory corruption vulnerabilities often serve as stepping stones for privilege escalation attacks, especially when combined with other weaknesses in the browser's memory management systems. The vulnerability's classification aligns with ATT&CK technique T1203, which covers legitimate programs that are used to gain access to system resources, particularly when the initial exploitation vector leads to memory corruption that can be extended for more comprehensive compromise.
Mitigation strategies for CVE-2011-3916 primarily focus on immediate software updates to the patched Chrome versions that properly validate PDF cross-reference entries. Users should ensure their browsers are updated to version 16.0.912.63 or later, which includes enhanced input validation and bounds checking mechanisms for PDF parsing operations. Organizations should implement automated patch management systems to ensure all user devices receive updates promptly, particularly in environments where PDF documents are frequently encountered. Additional protective measures include implementing web content filtering solutions that can block or sandbox PDF content, disabling automatic PDF rendering in browsers when possible, and maintaining updated security software that can detect and prevent exploitation attempts. Network administrators should also consider implementing monitoring solutions that can detect abnormal browser behavior patterns that might indicate exploitation attempts, as the vulnerability's signature characteristics can be identified through behavioral analysis of network traffic and system logs.