CVE-2017-5069 in Chrome
Summary
by MITRE
Incorrect MIME type of XSS-Protection reports in Blink in Google Chrome prior to 58.0.3029.81 for Linux, Windows, and Mac, and 58.0.3029.83 for Android, allowed a remote attacker to circumvent Cross-Origin Resource Sharing checks via a crafted HTML page.
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Analysis
by VulDB Data Team • 09/17/2020
The vulnerability identified as CVE-2017-5069 represents a critical security flaw in Google Chrome's Blink rendering engine that affected multiple platforms including Linux, Windows, Mac, and Android. This issue specifically pertains to the improper handling of MIME types in Cross-Site Scripting (XSS) protection reports, creating a significant bypass opportunity for remote attackers. The vulnerability was present in Chrome versions prior to 58.0.3029.81 for desktop platforms and 58.0.3029.83 for Android devices, making it a widespread concern across the Chrome user base. The flaw essentially allowed attackers to manipulate how the browser interpreted security reports, potentially undermining the fundamental security mechanisms designed to protect users from cross-site scripting attacks.
The technical root cause of this vulnerability stems from how Blink processes MIME types when handling XSS-Protection reports. When Chrome generates reports for potential XSS attacks, it should properly validate and enforce Cross-Origin Resource Sharing (CORS) policies to prevent unauthorized access to resources. However, the incorrect MIME type handling allowed attackers to craft malicious HTML pages that could manipulate the browser's interpretation of these security reports. This misconfiguration created a pathway where the browser would not properly enforce CORS restrictions, effectively allowing attackers to bypass security controls that should have prevented unauthorized cross-origin resource access. The vulnerability specifically exploited the relationship between MIME type validation and security policy enforcement within Chrome's security architecture.
The operational impact of CVE-2017-5069 was substantial as it enabled remote attackers to perform cross-origin resource sharing bypass attacks without requiring user interaction or specific privileges. Attackers could craft specially designed HTML pages that would trick the browser into treating security reports with incorrect MIME types, thereby circumventing the normal CORS checks that should have prevented unauthorized access to sensitive resources. This vulnerability particularly affected web applications that relied on CORS for security boundaries, as attackers could exploit the flaw to access resources that should have been protected by cross-origin restrictions. The attack vector was particularly concerning because it could be executed through standard web browsing activities, making it difficult for users to detect or prevent such attacks.
This vulnerability aligns with CWE-20, which describes improper input validation, and relates to the broader category of security misconfigurations that affect web application security. The flaw also connects to ATT&CK technique T1059, which covers command and scripting interpreter, as it could enable attackers to execute malicious code through manipulated security reports. Additionally, the vulnerability demonstrates characteristics of privilege escalation through browser security bypasses, similar to techniques described in ATT&CK framework under web application attacks. The issue highlights the importance of proper MIME type validation in security-critical components and the potential for seemingly minor configuration errors to create significant security vulnerabilities in browser environments.
The recommended mitigations for CVE-2017-5069 involve immediate updates to Chrome browser versions that contain the fix, ensuring that all affected platforms receive the security patch. Organizations should also implement additional monitoring for suspicious cross-origin resource access patterns and consider deploying web application firewalls that can detect and block malicious HTML content. Browser security configurations should be reviewed to ensure proper enforcement of CORS policies, and security teams should monitor for any attempts to exploit this vulnerability through social engineering or malicious websites. Regular security assessments of web applications that rely on CORS for protection are essential to identify potential exploitation vectors. The vulnerability underscores the importance of maintaining up-to-date browser software and implementing layered security approaches to protect against sophisticated cross-origin attacks that exploit browser security mechanisms.