CVE-2016-5184 in Chrome
Summary
by MITRE
PDFium in Google Chrome prior to 54.0.2840.59 for Windows, Mac, and Linux; 54.0.2840.85 for Android incorrectly handled object lifecycles in CFFL_FormFillter::KillFocusForAnnot, which allowed a remote attacker to potentially exploit heap corruption via crafted PDF files.
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Analysis
by VulDB Data Team • 10/12/2022
The vulnerability identified as CVE-2016-5184 resides within PDFium, the PDF rendering engine used by Google Chrome across multiple platforms including Windows, Mac, Linux, and Android. This flaw specifically affects Chrome versions prior to 54.0.2840.59 for desktop platforms and 54.0.2840.85 for Android systems. The vulnerability stems from improper handling of object lifecycles within the CFFL_FormFillter::KillFocusForAnnot method, which represents a critical memory management issue that can lead to heap corruption when processing maliciously crafted PDF files.
The technical nature of this vulnerability involves a classic heap corruption exploit that occurs during the handling of form field focus changes in PDF documents. When Chrome processes PDF files containing specially crafted objects, the CFFL_FormFillter::KillFocusForAnnot function fails to properly manage the lifecycle of certain objects, leading to situations where memory that has been freed or reallocated is still being accessed or modified. This improper object lifecycle management creates opportunities for attackers to manipulate memory layout and execute arbitrary code on the target system. The vulnerability manifests as heap corruption because the PDFium engine does not adequately validate object references or enforce proper memory deallocation sequences during form field interaction handling.
From an operational perspective, this vulnerability presents a significant remote code execution risk that can be exploited through malicious PDF files delivered via email attachments, web downloads, or compromised websites. Attackers can craft PDF documents that, when opened in affected Chrome versions, trigger the vulnerable code path and cause heap corruption. The exploitation requires no user interaction beyond opening the malicious document, making it particularly dangerous in phishing campaigns or targeted attacks. The vulnerability affects all supported platforms where Chrome is installed, amplifying its potential impact across different operating environments and user bases.
The security implications of CVE-2016-5184 align with CWE-415 and CWE-416, which address improper lifetime management of memory resources and double free errors respectively. This vulnerability also maps to ATT&CK technique T1203, which involves exploitation of software vulnerabilities for privilege escalation and code execution. Organizations should immediately update to Chrome versions 54.0.2840.59 or later for desktop platforms and 54.0.2840.85 or later for Android to mitigate this risk. Additionally, implementing browser security policies that restrict PDF handling, using sandboxing mechanisms, and maintaining regular security updates form essential defensive measures against this and similar vulnerabilities. Network-based protections such as web application firewalls and email filtering systems can provide additional layers of defense while the primary mitigation involves ensuring all affected systems are patched and updated to the latest Chrome releases.