CVE-2017-5111 in Chrome
Summary
by MITRE
A use after free in PDFium in Google Chrome prior to 61.0.3163.79 for Linux, Windows, and Mac allowed a remote attacker to potentially exploit memory corruption via a crafted PDF file.
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Analysis
by VulDB Data Team • 11/14/2019
The vulnerability identified as CVE-2017-5111 represents a critical use-after-free condition within PDFium, the PDF rendering library employed by Google Chrome across multiple operating systems. This flaw emerged in Chrome versions prior to 61.0.3163.79 and specifically affected Linux, Windows, and Mac platforms, creating a significant security risk for users who interacted with PDF documents. The vulnerability stems from improper memory management during the processing of maliciously crafted PDF files, where the application attempts to access memory that has already been freed, leading to potential exploitation scenarios.
The technical nature of this vulnerability aligns with CWE-416, which classifies use-after-free conditions as a fundamental memory safety issue. When PDFium processes a specially constructed PDF document, it allocates memory for various objects and data structures to render the document properly. However, due to insufficient validation and memory management controls, the application may free memory regions while still maintaining pointers to those locations. A remote attacker can exploit this by crafting a PDF file that triggers specific parsing sequences, causing the application to execute code in the freed memory space. This behavior can result in arbitrary code execution, allowing attackers to gain control over the affected system.
The operational impact of CVE-2017-5111 extends beyond simple memory corruption, as it provides attackers with a pathway for remote code execution through web-based PDF rendering. The vulnerability's exploitation requires a victim to open a malicious PDF file, typically through web browsing or email attachments, making it particularly dangerous in enterprise environments where users frequently interact with PDF documents. The attack surface is broad due to Chrome's widespread adoption across multiple platforms, and the exploit can be delivered through various vectors including compromised websites, phishing campaigns, or malicious email attachments. This vulnerability directly maps to attack techniques described in the MITRE ATT&CK framework under the T1203 category, which covers legitimate credentials and T1059 for command and scripting interpreter, as successful exploitation could lead to full system compromise.
The remediation for CVE-2017-5111 required immediate patching of Chrome versions to 61.0.3163.79 or later, which implemented proper memory management controls and added additional validation checks within PDFium's parsing routines. Security researchers recommended that organizations prioritize patch deployment across all affected systems, particularly those running older Chrome versions. The fix involved strengthening memory allocation and deallocation procedures within the PDF rendering engine, ensuring that freed memory regions are properly invalidated and that all pointers are cleared after memory release operations. Additionally, browser vendors and system administrators should implement defense-in-depth strategies including PDF sandboxing, content filtering, and user education to reduce the risk of exploitation. Organizations utilizing Chrome should also consider implementing network-based security controls to detect and block suspicious PDF content, as the vulnerability's exploitation can occur without user interaction in certain scenarios, making it particularly challenging to defend against through traditional user awareness training alone.