CVE-2018-6153 in Chrome
Summary
by MITRE
A precision error in Skia in Google Chrome prior to 68.0.3440.75 allowed a remote attacker who had compromised the renderer process to perform an out of bounds memory write via a crafted HTML page.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 06/26/2023
The vulnerability identified as CVE-2018-6153 represents a critical precision error within the Skia graphics library that forms a fundamental component of Google Chrome's rendering engine. This flaw existed in Chrome versions prior to 68.0.3440.75 and created a pathway for remote attackers to execute out of bounds memory write operations when a compromised renderer process encountered a specially crafted HTML page. The Skia library, which handles 2D graphics rendering across multiple platforms including Android, Chrome OS, and the web, contains a mathematical precision issue that manifests when processing certain graphical operations. This precision error occurs during the handling of floating point calculations that determine memory allocation boundaries for graphical elements, leading to situations where memory addresses exceed their intended boundaries.
The technical exploitation of this vulnerability requires an attacker to first compromise the renderer process, which typically involves achieving code execution within Chrome's sandboxed environment through a separate initial vulnerability. Once inside the renderer process, the attacker can construct a malicious HTML page that triggers the precision error in Skia's mathematical computations. The flaw specifically affects how the graphics library calculates memory offsets when rendering complex graphical elements, particularly those involving transformations, scaling operations, or anti-aliasing algorithms. When the precision error occurs, it causes the graphics subsystem to write data beyond the allocated memory buffer, potentially overwriting adjacent memory regions and enabling arbitrary code execution or system instability.
The operational impact of this vulnerability extends beyond simple memory corruption, as it represents a sophisticated attack vector that could be leveraged for privilege escalation or system compromise. The out of bounds memory write operation creates opportunities for attackers to overwrite critical data structures, function pointers, or return addresses within the renderer process, potentially leading to complete system compromise. This vulnerability aligns with CWE-129, which describes improper validation of array indices, and demonstrates how mathematical precision errors in graphics libraries can create exploitable conditions. The attack scenario typically involves a multi-stage process where initial access is gained through a different vulnerability, followed by the exploitation of this precision error to achieve more significant system control. The vulnerability's classification under ATT&CK technique T1059.007 for scripting languages indicates how attackers might leverage HTML-based payloads to execute malicious code through browser components.
Mitigation strategies for CVE-2018-6153 primarily focus on updating to Chrome version 68.0.3440.75 or later, which contains the necessary patches to address the Skia precision error. Organizations should implement comprehensive patch management procedures to ensure all Chrome installations are updated promptly, as this vulnerability could be exploited in targeted attacks against specific user populations. Additional protective measures include implementing strict content security policies, enabling sandboxing features, and monitoring for unusual memory access patterns or graphical rendering anomalies that might indicate exploitation attempts. Network security teams should also consider deploying web application firewalls and content filtering solutions to block malicious HTML content that might trigger this vulnerability. The fix implemented by Google addresses the underlying mathematical precision issue in Skia's memory calculation algorithms, ensuring that graphical operations maintain proper bounds checking and prevent memory corruption during rendering operations.