CVE-2016-1626 in Chrome
Summary
by MITRE
The opj_pi_update_decode_poc function in pi.c in OpenJPEG, as used in PDFium in Google Chrome before 48.0.2564.109, miscalculates a certain layer index value, which allows remote attackers to cause a denial of service (out-of-bounds read) via a crafted PDF document.
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Analysis
by VulDB Data Team • 07/08/2022
The vulnerability identified as CVE-2016-1626 represents a critical out-of-bounds read flaw within the OpenJPEG library implementation, specifically within the opj_pi_update_decode_poc function located in the pi.c source file. This vulnerability manifests when processing JPEG 2000 encoded content within PDF documents, creating a scenario where an attacker can manipulate the layer index calculation to access memory locations beyond the allocated buffer boundaries. The flaw exists in the PDFium component of Google Chrome, affecting versions prior to 48.0.2564.109, where the library fails to properly validate or sanitize the layer index values during the decoding process of progressive JPEG 2000 streams.
The technical exploitation of this vulnerability occurs through the manipulation of crafted PDF documents that contain specially constructed JPEG 2000 data streams. When the PDFium renderer processes such malicious content, the opj_pi_update_decode_poc function incorrectly calculates the layer index value, leading to an attempt to read memory beyond the intended buffer limits. This miscalculation results in a memory access violation that can trigger a crash or unpredictable behavior within the Chrome browser process, effectively enabling a denial of service attack against the target system. The vulnerability stems from insufficient input validation and boundary checking mechanisms within the JPEG 2000 decoding pipeline, particularly in how layer indices are computed and validated during progressive decoding operations.
From an operational impact perspective, this vulnerability poses significant risks to end-user security and system stability, as it can be exploited through the web browser's PDF rendering capabilities without requiring any special privileges or user interaction beyond visiting a malicious webpage. Attackers can craft PDF documents containing malformed JPEG 2000 data that, when opened in vulnerable Chrome versions, will trigger the out-of-bounds read condition. The resulting denial of service can disrupt user productivity and potentially provide attackers with opportunities to execute more sophisticated attacks if combined with other vulnerabilities. This flaw particularly affects enterprise environments where users frequently access PDF documents from untrusted sources, making it a prime target for phishing campaigns and targeted attacks.
The vulnerability aligns with CWE-129, which addresses improper validation of array indices, and demonstrates characteristics consistent with the ATT&CK technique T1059.007 for command and scripting interpreter usage in exploitation contexts. Organizations should implement immediate mitigation strategies including updating to Chrome version 48.0.2564.109 or later, which contains the patched OpenJPEG library implementation. Additional protective measures include deploying web application firewalls, implementing PDF content filtering, and establishing security policies that restrict PDF document access from untrusted sources. Network administrators should also consider monitoring for suspicious PDF-related network traffic patterns and implementing sandboxing mechanisms for PDF processing to limit potential exploitation impact. The vulnerability underscores the importance of proper input validation in multimedia libraries and highlights the need for comprehensive security testing of third-party components integrated into browser applications.