CVE-2016-1613 in Chrome
Summary
by MITRE
Multiple use-after-free vulnerabilities in the formfiller implementation in PDFium, as used in Google Chrome before 48.0.2564.82, allow remote attackers to cause a denial of service or possibly have unspecified other impact via a crafted PDF document, related to improper tracking of the destruction of (1) IPWL_FocusHandler and (2) IPWL_Provider objects.
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Analysis
by VulDB Data Team • 07/06/2022
The vulnerability CVE-2016-1613 represents a critical use-after-free condition within the PDFium library's formfiller component, which serves as the underlying engine for processing PDF forms in Google Chrome browser versions prior to 48.0.2564.82. This flaw resides in the improper management of object lifecycle within the formfiller implementation, specifically affecting two distinct object types: IPWL_FocusHandler and IPWL_Provider. The vulnerability demonstrates the classic characteristics of memory safety issues where program code continues to reference memory locations after they have been freed, creating potential exploitation vectors for remote attackers.
The technical exploitation of this vulnerability occurs through carefully crafted malicious PDF documents that trigger specific conditions during form processing. When Chrome encounters such documents, the formfiller component attempts to manage focus and provider objects in a manner that leads to premature memory deallocation followed by subsequent access attempts to these freed memory regions. This improper object tracking mechanism creates a scenario where the IPWL_FocusHandler and IPWL_Provider objects are destroyed while still being referenced elsewhere in the execution flow, resulting in undefined behavior that can manifest as application crashes or potentially more severe consequences.
From an operational perspective, this vulnerability presents significant risks to end users and organizations relying on Google Chrome for PDF document processing. The remote attack vector means that simply opening a malicious PDF document could trigger the exploit without any user interaction beyond the initial document opening. The potential impact extends beyond simple denial of service to include unspecified other impacts that could potentially allow for arbitrary code execution or privilege escalation depending on the specific memory corruption patterns. This vulnerability directly aligns with CWE-416 which defines use-after-free conditions as a fundamental memory safety issue, and maps to ATT&CK technique T1203 for legitimate program execution and T1059 for command and scripting interpreter usage in exploitation scenarios.
The mitigation strategy for CVE-2016-1613 requires immediate patching of affected Chrome versions to 48.0.2564.82 or later, which contains the necessary fixes for proper object lifecycle management within the PDFium formfiller implementation. Organizations should implement comprehensive browser update policies and consider deploying additional security controls such as PDF sandboxing mechanisms and content filtering solutions. Security teams should monitor for indicators of compromise related to PDF-based attacks and maintain awareness of related vulnerabilities in the PDF processing ecosystem. The fix addresses the core issue by implementing proper reference counting and object validation mechanisms that prevent the premature destruction of objects while maintaining active references, thereby eliminating the use-after-free conditions that enabled exploitation.