CVE-2017-5126 in Chrome
Summary
by MITRE
A use after free in PDFium in Google Chrome prior to 62.0.3202.62 allowed a remote attacker to potentially exploit heap corruption via a crafted PDF file.
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Analysis
by VulDB Data Team • 02/06/2023
The vulnerability identified as CVE-2017-5126 represents a critical use-after-free condition within the PDFium library component of Google Chrome browser versions prior to 62.0.3202.62. This flaw exists in the handling of PDF documents and creates a remote code execution vector that attackers can exploit through maliciously crafted PDF files. The issue stems from improper memory management where freed memory blocks are still referenced after being deallocated, creating opportunities for arbitrary code execution. The vulnerability is particularly concerning because PDF files are commonly encountered in web browsing scenarios, making this attack vector highly accessible to threat actors.
The technical implementation of this vulnerability occurs within the PDFium rendering engine which processes PDF documents in Chrome. When parsing specific PDF structures, the code fails to properly manage object references, leading to a situation where memory allocated to a PDF object is freed but subsequent operations attempt to access that same memory location. This use-after-free condition creates a heap corruption scenario that can be exploited to overwrite memory contents with attacker-controlled data. The flaw demonstrates characteristics consistent with CWE-416, which specifically addresses use-after-free vulnerabilities where memory is accessed after it has been freed, and aligns with ATT&CK technique T1203, which covers exploitation for execution through memory corruption vulnerabilities.
The operational impact of this vulnerability extends beyond simple browser compromise, as successful exploitation can lead to complete system control. Attackers can leverage this vulnerability to execute arbitrary code on affected systems, potentially gaining unauthorized access to sensitive data, installing malware, or establishing persistent backdoors. The remote nature of the attack means that users need only open a malicious PDF file to be compromised, making this vulnerability particularly dangerous in phishing campaigns or when visiting compromised websites. The vulnerability affects a wide range of Chrome versions and operating systems, amplifying its potential impact across different environments and user bases.
Mitigation strategies for CVE-2017-5126 primarily focus on immediate software updates and security hardening measures. The most effective remediation is updating to Chrome version 62.0.3202.62 or later, which includes patches specifically addressing the memory management issues in PDFium. Organizations should implement comprehensive patch management protocols to ensure all systems receive updates promptly. Additional protective measures include enabling Chrome's built-in security features such as sandboxing and site isolation, implementing web content filtering solutions, and deploying network-based intrusion detection systems to monitor for suspicious PDF-related traffic patterns. Security teams should also consider restricting PDF file handling in enterprise environments and educating users about the risks of opening untrusted PDF documents. The vulnerability highlights the importance of regular security assessments and the need for robust memory safety practices in software development, particularly in components that process untrusted input data.