CVE-2017-5118 in Chrome
Summary
by MITRE
Blink in Google Chrome prior to 61.0.3163.79 for Mac, Windows, and Linux, and 61.0.3163.81 for Android, failed to correctly propagate CSP restrictions to javascript scheme pages, which allowed a remote attacker to bypass content security policy via a crafted HTML page.
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Analysis
by VulDB Data Team • 01/11/2021
The vulnerability identified as CVE-2017-5118 represents a critical content security policy enforcement flaw within the Blink rendering engine that powers Google Chrome across multiple platforms. This issue specifically affected Chrome versions prior to 61.0.3163.79 on Mac, Windows, and Linux systems, as well as version 61.0.3163.81 on Android devices. The flaw resides in how the browser handles content security policy restrictions when processing javascript scheme pages, creating a significant bypass mechanism that undermines the security controls designed to protect users from malicious web content.
The technical implementation of this vulnerability stems from improper handling of content security policy directives when JavaScript scheme URLs are processed within the browser's rendering engine. When a web page containing crafted HTML elements attempts to execute JavaScript code, the browser fails to properly enforce the content security policy restrictions that should normally prevent execution of unauthorized scripts. This misconfiguration allows attackers to craft malicious HTML pages that can bypass the security boundaries established by CSP headers, effectively neutralizing the protection mechanisms that browsers rely upon to prevent cross-site scripting attacks and other code injection vulnerabilities.
From an operational impact perspective, this vulnerability creates a severe risk for users browsing the web, as remote attackers can exploit this flaw to circumvent the fundamental security protections that content security policy provides. The attack surface is particularly concerning because it affects multiple operating systems and platforms, making it a widespread concern for organizations relying on Chrome as their primary browser. An attacker could craft a malicious webpage that appears legitimate but contains embedded JavaScript that would execute without proper CSP restrictions, potentially leading to data theft, session hijacking, or the execution of arbitrary code on victim machines.
The vulnerability aligns with CWE-16, which describes architecture and design flaws in security controls, and specifically relates to improper enforcement of security policies within web browsers. From an ATT&CK framework perspective, this issue maps to T1211 - Exploitation for Defense Evasion, as it allows attackers to bypass security controls that would normally prevent malicious code execution. Additionally, it connects to T1059.007 - Command and Scripting Interpreter: JavaScript, representing the exploitation of JavaScript execution capabilities through improper security boundary enforcement.
Organizations should immediately update their Chrome installations to versions 61.0.3163.79 or later for Mac, Windows, and Linux systems, and version 61.0.3163.81 or later for Android devices to remediate this vulnerability. Security teams should also implement additional monitoring for suspicious JavaScript execution patterns and ensure that content security policy headers are properly configured and enforced at the network level. Browser security updates should be prioritized as part of routine maintenance procedures, and organizations should consider implementing browser isolation techniques as additional defense layers against such vulnerabilities.