CVE-2018-18338 in Chrome
Summary
by MITRE
Incorrect, thread-unsafe use of SkImage in Canvas in Google Chrome prior to 71.0.3578.80 allowed a remote attacker to potentially exploit heap corruption via a crafted HTML page.
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Analysis
by VulDB Data Team • 06/18/2023
The vulnerability identified as CVE-2018-18338 represents a critical thread-unsafe memory management issue within Google Chrome's rendering engine, specifically affecting the SkImage implementation within the Canvas API. This flaw existed in Chrome versions prior to 71.0.3578.80 and enabled remote attackers to potentially execute arbitrary code through carefully crafted HTML pages. The vulnerability stems from improper handling of shared resources in a multi-threaded environment where concurrent access to SkImage objects was not properly synchronized, creating opportunities for heap corruption and memory safety violations.
The technical root cause of this vulnerability lies in the improper implementation of thread safety mechanisms within Chrome's graphics rendering pipeline. When multiple threads attempt to access or modify SkImage objects simultaneously without proper locking mechanisms, race conditions can occur that lead to memory corruption. This type of vulnerability falls under CWE-362, which specifically addresses race conditions in concurrent programming environments. The flaw manifests when Canvas operations involving image processing are executed in parallel contexts, where the SkImage object's internal state becomes inconsistent due to simultaneous read and write operations from different execution threads.
The operational impact of this vulnerability extends beyond simple memory corruption, as it provides attackers with a potential pathway for remote code execution. When a malicious webpage loads and triggers specific Canvas operations with SkImage objects, the heap corruption can be exploited to overwrite critical memory locations, potentially allowing attackers to inject and execute arbitrary code with the privileges of the Chrome process. This represents a significant escalation from typical web-based vulnerabilities, as it can lead to full system compromise if successful. The vulnerability is particularly dangerous because it leverages the legitimate Canvas API functionality that is commonly used in web applications, making it difficult to detect through traditional security monitoring approaches.
Mitigation strategies for CVE-2018-18338 primarily involve updating to Chrome version 71.0.3578.80 or later, which includes proper thread synchronization mechanisms for SkImage operations. Organizations should implement comprehensive patch management procedures to ensure all Chrome installations are updated promptly. Additionally, browser hardening measures such as sandboxing, content security policies, and strict MIME type checking can provide additional defense-in-depth layers. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and remote code execution through browser exploitation, specifically targeting the browser's rendering engine as a vector for system compromise. Network administrators should also consider implementing web filtering solutions and monitoring for suspicious Canvas API usage patterns that might indicate exploitation attempts.