CVE-2018-20072 in Chrome
Summary
by MITRE • 09/24/2024
Insufficient data validation in PDF in Google Chrome prior to 73.0.3683.75 allowed a remote attacker to perform out of bounds memory access via a crafted PDF file. (Chromium security severity: Low)
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Analysis
by VulDB Data Team • 03/09/2025
This vulnerability represents a classic buffer overflow condition that occurred within Google Chrome's PDF rendering engine, specifically affecting versions prior to 73.0.3683.75. The issue stems from inadequate input validation when processing maliciously crafted PDF files, creating a scenario where attacker-controlled data can manipulate memory access patterns beyond allocated boundaries. The vulnerability falls under the broader category of memory safety issues that have historically plagued document processing components across various software platforms.
The technical flaw manifests when Chrome's PDF parser encounters malformed data structures within a PDF file, particularly in how it handles object references and memory allocation for embedded content. Attackers can construct PDF documents that contain oversized arrays or improperly formatted cross-reference tables, which when processed by the vulnerable browser trigger out-of-bounds memory access. This condition typically occurs during the parsing phase when the application attempts to read or write data beyond the intended memory regions allocated for PDF objects. The Chromium security team classified this as low severity, but such vulnerabilities can often be leveraged as initial access vectors in more sophisticated attack chains.
The operational impact of this vulnerability extends beyond simple memory corruption, as it provides a potential pathway for remote code execution when combined with other exploit primitives. While the immediate effect may appear limited to memory access violations, the underlying memory corruption can be exploited through techniques such as heap spraying or return-oriented programming to achieve arbitrary code execution. This type of vulnerability is particularly dangerous in enterprise environments where users frequently encounter PDF documents from untrusted sources, making it a prime candidate for phishing campaigns or supply chain attacks. The vulnerability aligns with CWE-129, which addresses insufficient validation of length of data, and demonstrates how improper bounds checking can create exploitable conditions.
Mitigation strategies for this vulnerability primarily involve updating to Chrome version 73.0.3683.75 or later, which includes patched PDF parsing routines with enhanced validation mechanisms. Organizations should also implement additional security controls such as PDF sandboxing features, restricted file type handling, and network segmentation to limit the potential impact of successful exploitation attempts. The ATT&CK framework categorizes this vulnerability under T1059.007 for PDF-based attack vectors, emphasizing the importance of endpoint detection and response capabilities to identify suspicious PDF processing activities. Security teams should monitor for anomalous memory access patterns or unusual PDF parsing behavior that might indicate exploitation attempts, as these indicators can help detect advanced persistent threats leveraging similar vulnerabilities.