CVE-2018-18336 in Chrome
Summary
by MITRE
Incorrect object lifecycle in PDFium in Google Chrome prior to 71.0.3578.80 allowed a remote attacker to potentially exploit heap corruption via a crafted PDF file.
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Analysis
by VulDB Data Team • 06/18/2023
CVE-2018-18336 represents a critical heap corruption vulnerability within PDFium, the PDF rendering library used by Google Chrome and numerous other applications. This flaw stems from improper object lifecycle management during PDF document processing, specifically when handling crafted malicious PDF files that trigger memory allocation and deallocation sequences in an incorrect order. The vulnerability manifests when PDFium fails to properly manage object references and memory cleanup operations, creating conditions where attacker-controlled input can manipulate the heap structure and lead to arbitrary code execution. The issue falls under CWE-415 which describes double free errors and CWE-416 which covers use after free conditions, both of which are common in memory management flaws. From an operational perspective, this vulnerability enables remote code execution attacks where adversaries can craft malicious PDF documents that, when opened in affected Chrome versions, cause the browser to crash or execute arbitrary code with the privileges of the browser process. The attack surface is broad given Chrome's widespread usage and PDF files' commonality in email attachments and web downloads, making this a particularly dangerous flaw for enterprise environments. The vulnerability exists in Chrome versions prior to 71.0.3578.80, representing a significant window of exposure for users who had not yet updated their browsers. The exploitation requires a user to open a specially crafted PDF file, making social engineering a critical component of successful attacks, though the underlying technical flaw remains in the PDFium library itself. This vulnerability aligns with ATT&CK technique T1203 which covers exploitation for client execution, specifically targeting browser-based attack vectors. Organizations should prioritize immediate patching of Chrome installations to version 71.0.3578.80 or later, as this represents the first version that properly addresses the object lifecycle management issues in PDFium. Network-based mitigations including PDF file scanning and web application firewalls can provide additional defense layers, though they cannot fully compensate for the underlying memory corruption issue. Security teams should also implement user education programs to reduce the risk of opening untrusted PDF files, particularly in high-risk environments where zero-day exploits are more likely to be targeted. The vulnerability demonstrates the critical importance of proper memory management in widely-used libraries and highlights the need for continuous security auditing of core components in browser ecosystems.