CVE-2016-5163 in Chrome
Summary
by MITRE
The bidirectional-text implementation in Google Chrome before 53.0.2785.89 on Windows and OS X and before 53.0.2785.92 on Linux does not ensure left-to-right (LTR) rendering of URLs, which allows remote attackers to spoof the address bar via crafted right-to-left (RTL) Unicode text, related to omnibox/SuggestionView.java and omnibox/UrlBar.java in Chrome for Android.
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Analysis
by VulDB Data Team • 09/14/2022
The vulnerability described in CVE-2016-5163 represents a sophisticated text rendering issue within Google Chrome's bidirectional text handling mechanism that specifically affects the user interface elements responsible for displaying web addresses in the browser's address bar. This flaw exists in Chrome versions prior to 53.0.2785.89 on Windows and OS X systems and before 53.0.2785.92 on Linux platforms, with the Android version also being impacted. The vulnerability stems from the improper handling of right-to-left Unicode text characters within the omnibox component, which is responsible for displaying URLs and search suggestions in the browser's address bar.
The technical implementation flaw occurs in the omnibox/SuggestionView.java and omnibox/UrlBar.java Java source files within Chrome's codebase, where the bidirectional text rendering logic fails to properly enforce left-to-right rendering of URLs even when they contain right-to-left Unicode characters. This creates a scenario where attackers can craft malicious URLs containing Unicode characters that appear to be legitimate web addresses but actually display differently due to the bidirectional text rendering algorithm. The vulnerability specifically targets the URL display mechanism in Chrome's address bar, allowing attackers to manipulate how URLs are visually presented to users.
The operational impact of this vulnerability is severe as it enables attackers to perform address bar spoofing attacks that can deceive users into believing they are visiting legitimate websites when they are actually navigating to malicious domains. This form of attack leverages the Unicode bidirectional algorithm to make malicious URLs appear to begin with trusted domain names or prefixes, making it particularly dangerous for phishing and social engineering campaigns. The vulnerability essentially allows attackers to manipulate the visual presentation of URLs in a way that bypasses normal user verification mechanisms, potentially leading to unauthorized data theft, malware distribution, or financial fraud.
This vulnerability aligns with CWE-174, which addresses the weakness in bidirectional text handling and text rendering, and relates to ATT&CK technique T1059.001 for operating system command and scripting interface. The attack vector specifically targets user interface deception through text manipulation, which is a common approach in modern phishing attacks. The vulnerability represents a classic case of input validation failure in UI rendering components, where the application does not properly sanitize or enforce text directionality for security-critical display elements.
Mitigation strategies for this vulnerability require immediate patching of Chrome installations to versions 53.0.2785.89 or later on Windows and OS X, and 53.0.2785.92 or later on Linux systems, with Android users needing to update to the corresponding secure versions. Organizations should implement browser security policies that enforce automatic updates and regularly monitor for vulnerable browser versions. Additionally, user education regarding URL verification practices remains crucial, though the technical fix through browser updates is the primary defense mechanism. The fix implemented by Google involved strengthening the bidirectional text rendering logic to ensure that URLs are always displayed in left-to-right order regardless of embedded Unicode characters, effectively neutralizing the spoofing capability.