CVE-2020-6558 in Chrome
Summary
by MITRE
Insufficient policy enforcement in iOSWeb in Google Chrome on iOS prior to 85.0.4183.83 allowed a remote attacker to bypass navigation restrictions via a crafted HTML page.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 09/22/2020
The vulnerability identified as CVE-2020-6558 represents a critical security flaw in the iOSWeb component of Google Chrome on iOS platforms. This issue stems from inadequate policy enforcement mechanisms that govern navigation behavior within the browser's web rendering engine. The vulnerability specifically affects versions of Chrome prior to 85.0.4183.83, leaving users exposed to potential exploitation through malicious web content. The flaw manifests when a remote attacker crafts a specially designed HTML page that can circumvent established navigation restrictions, effectively undermining the browser's security controls.
The technical nature of this vulnerability lies in the insufficient validation and enforcement of navigation policies within the iOSWeb framework. When users encounter a crafted HTML page, the browser fails to properly enforce its intended navigation restrictions, allowing malicious actors to redirect or manipulate user navigation flows. This represents a breakdown in the browser's security architecture where the policy enforcement layer does not adequately validate or control the navigation behavior of web content. The vulnerability can be classified under CWE-693, which deals with protection mechanism failures, specifically in the context of navigation restrictions and access control enforcement. The flaw essentially creates a bypass mechanism that allows unauthorized navigation paths that should have been blocked by security policies.
From an operational impact perspective, this vulnerability poses significant risks to user security and privacy. Attackers can exploit this weakness to perform phishing attacks, redirect users to malicious websites, or manipulate browser behavior in ways that compromise user safety. The remote nature of the attack means users can be targeted simply by visiting compromised websites or clicking on malicious links, without requiring any special privileges or local access. This vulnerability directly impacts the browser's ability to maintain secure navigation boundaries, potentially allowing attackers to execute various malicious activities including credential theft, malware distribution, or data exfiltration. The attack surface is particularly concerning given the widespread use of Chrome on iOS devices and the trust users place in the browser's security mechanisms.
The mitigation strategy for CVE-2020-6558 involves immediate updating of Google Chrome to version 85.0.4183.83 or later, which contains the necessary patches to address the policy enforcement deficiencies. Organizations should implement comprehensive patch management procedures to ensure all affected iOS devices receive the update promptly. Additionally, security teams should conduct vulnerability assessments to identify any systems potentially exposed to this threat before the patch was applied. Network monitoring solutions should be enhanced to detect and block known malicious domains that might exploit this vulnerability. The remediation aligns with ATT&CK technique T1059.001, which covers command and scripting interpreter, as attackers could potentially use the navigation bypass to execute malicious scripts or redirect users to compromised sites. Users should also be educated about the risks of visiting untrusted websites and the importance of keeping their browsers updated. This vulnerability highlights the critical importance of maintaining up-to-date security controls and demonstrates how seemingly minor policy enforcement gaps can create significant security risks in web browsers.