CVE-2016-1649 in Chrome
Summary
by MITRE
The Program::getUniformInternal function in Program.cpp in libANGLE, as used in Google Chrome before 49.0.2623.108, does not properly handle a certain data-type mismatch, which allows remote attackers to cause a denial of service (buffer overflow) or possibly have unspecified other impact via crafted shader stages.
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Analysis
by VulDB Data Team • 07/11/2022
The vulnerability identified as CVE-2016-1649 resides within the libANGLE library component of Google Chrome, specifically in the Program::getUniformInternal function located in Program.cpp. This flaw represents a critical buffer overflow vulnerability that stems from improper handling of data-type mismatches during shader processing operations. The affected version range includes Chrome versions prior to 49.0.2623.108, making it a significant security concern for users running older browser versions. The vulnerability operates at the intersection of graphics rendering and shader compilation, where the library fails to properly validate or sanitize uniform variable data types during shader stage processing, creating an exploitable condition that can be triggered through maliciously crafted shader code.
The technical implementation of this vulnerability involves the manipulation of uniform variables within OpenGL shader programs, where the getUniformInternal function does not adequately verify the consistency between expected and actual data types during uniform parameter retrieval. This mismatch creates a scenario where attacker-controlled shader code can cause memory corruption by writing beyond allocated buffer boundaries. The flaw manifests when the function processes uniform variables that have different data representations between the shader compiler and the runtime environment, leading to unpredictable behavior including memory overwrite conditions. This type of vulnerability falls under CWE-121, which describes stack-based buffer overflow conditions, and can potentially be leveraged for more severe exploits depending on the execution context and memory layout.
From an operational perspective, this vulnerability enables remote attackers to execute denial of service attacks by causing Chrome to crash or become unresponsive through carefully constructed shader stages. The impact extends beyond simple service disruption, as the buffer overflow condition could potentially be exploited to execute arbitrary code in the context of the browser process, though the primary reported impact is denial of service. The vulnerability affects web applications that utilize WebGL or other graphics rendering capabilities, making it particularly dangerous in environments where users may encounter malicious content. Attackers can craft HTML5 WebGL content or other shader-based graphics elements that trigger the flawed code path when Chrome processes these graphics operations, effectively creating a remote attack vector through web browsers.
The mitigation strategies for CVE-2016-1649 primarily focus on immediate browser updates to versions 49.0.2623.108 or later where the vulnerability has been patched. Additionally, organizations should implement network-level controls to restrict access to untrusted WebGL content and consider browser security policies that limit shader complexity or disable certain graphics features. System administrators should also monitor for suspicious WebGL content and implement intrusion detection systems that can identify patterns associated with shader-based exploitation attempts. The patch addresses the underlying data-type validation issue by ensuring proper type checking and bounds verification during uniform variable processing, preventing the buffer overflow condition that previously occurred when mismatched data types were encountered during shader compilation and execution phases. This vulnerability demonstrates the importance of proper input validation in graphics rendering libraries and the potential for seemingly benign shader operations to become attack vectors when proper sanitization is lacking.