CVE-2016-1645 in Chrome
Summary
by MITRE
Multiple integer signedness errors in the opj_j2k_update_image_data function in j2k.c in OpenJPEG, as used in PDFium in Google Chrome before 49.0.2623.87, allow remote attackers to cause a denial of service (incorrect cast and out-of-bounds write) or possibly have unspecified other impact via crafted JPEG 2000 data.
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Analysis
by VulDB Data Team • 07/10/2022
The vulnerability CVE-2016-1645 represents a critical security flaw in the OpenJPEG library implementation within Google Chrome's PDFium component. This issue stems from multiple integer signedness errors within the opj_j2k_update_image_data function located in j2k.c file, creating a dangerous condition that can be exploited by remote attackers through carefully crafted JPEG 2000 image data. The flaw manifests as incorrect type casting operations that fail to properly handle signed and unsigned integer conversions, leading to potentially catastrophic memory corruption scenarios. The vulnerability affects Chrome versions prior to 49.0.2623.87, making it particularly concerning given the widespread usage of the browser and its integration with PDF rendering capabilities.
The technical nature of this vulnerability aligns with CWE-194, which describes the improper handling of signed and unsigned integer conversions, and specifically relates to CWE-121, which deals with stack-based buffer overflow conditions. The integer signedness errors occur when the opj_j2k_update_image_data function processes JPEG 2000 image data, where signed integer variables are incorrectly cast to unsigned types or vice versa, causing memory layout distortions. This incorrect casting leads to out-of-bounds write operations that can overwrite adjacent memory locations, potentially corrupting critical program data structures or executing arbitrary code. The vulnerability's exploitation requires an attacker to craft malicious JPEG 2000 data that triggers these specific integer conversion paths within the image processing pipeline, making it particularly insidious as it operates within legitimate image rendering contexts.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as the out-of-bounds write capabilities could potentially enable remote code execution or information disclosure. Attackers leveraging this flaw could cause Chrome to crash or behave unpredictably, leading to denial of service scenarios that disrupt user productivity and potentially provide footholds for more sophisticated attacks. The vulnerability's presence in PDFium makes it particularly dangerous since PDF documents are commonly encountered in web browsing scenarios, increasing the attack surface significantly. According to ATT&CK framework domain T1203, this vulnerability could be used to establish persistent access through browser-based exploitation, while T1499 covers the potential for denial of service as an initial compromise vector. The flaw's ability to cause incorrect casts and out-of-bounds writes creates a pathway for attackers to manipulate memory contents in ways that could compromise the entire browser sandbox.
Mitigation strategies for CVE-2016-1645 primarily involve updating to Chrome version 49.0.2623.87 or later, which includes the necessary patches to address the integer signedness errors in OpenJPEG's j2k.c implementation. Organizations should prioritize immediate patch deployment across all affected systems to prevent exploitation attempts. Additionally, implementing network-based security controls such as web application firewalls and content filtering systems can help detect and block malicious JPEG 2000 data before it reaches vulnerable systems. Browser hardening techniques including sandboxing and memory protection mechanisms should be enabled to limit potential exploitation impact even if the vulnerability is not immediately patched. Security monitoring should focus on detecting unusual memory access patterns or out-of-bounds write attempts that might indicate exploitation attempts. System administrators should also consider implementing least privilege access controls and regular security assessments to identify potential attack vectors that could leverage similar integer handling vulnerabilities in other components of the browser ecosystem.