CVE-2016-1671 in Chrome
Summary
by MITRE
Google Chrome before 50.0.2661.102 on Android mishandles / (slash) and \ (backslash) characters, which allows attackers to conduct directory traversal attacks via a file: URL, related to net/base/escape.cc and net/base/filename_util.cc.
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Analysis
by VulDB Data Team • 08/19/2022
The vulnerability identified as CVE-2016-1671 represents a critical directory traversal flaw in Google Chrome versions prior to 50.0.2661.102 on Android platforms. This security weakness stems from improper handling of forward slash and backslash characters within file URL processing, creating exploitable conditions that enable attackers to manipulate file paths and access unauthorized system resources. The vulnerability specifically affects the core URL handling mechanisms within Chrome's network stack, particularly in the net/base/escape.cc and net/base/filename_util.cc source files where path normalization and validation routines fail to properly sanitize input containing these special characters.
The technical implementation of this vulnerability exploits the inconsistent treatment of path separators in Chrome's file URL parsing logic. When processing file: URLs containing slash and backslash characters, the browser fails to adequately normalize these path components, allowing maliciously crafted URLs to bypass intended directory boundaries. This flaw operates at the application layer within Chrome's networking components, specifically targeting the file system access controls that should prevent unauthorized traversal beyond designated directories. The vulnerability is classified under CWE-22 as Improper Limitation of a Pathname to a Restricted Directory, which is a well-established category of path traversal attacks that have been extensively documented in cybersecurity literature and threat intelligence reports.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it enables attackers to potentially access sensitive files and directories that should remain protected from browser-based access. An attacker could craft malicious file: URLs that traverse directory structures to access system files, user data, or application resources that are not intended to be accessible through web browsing contexts. This capability poses significant risks to user privacy and system integrity, particularly on mobile platforms where users may have less awareness of potential security threats. The vulnerability is particularly dangerous in environments where Chrome is used as a primary browser for accessing web content, as it could be exploited through phishing attacks, malicious websites, or compromised web applications that load malicious content.
From a threat modeling perspective, this vulnerability aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter: PowerShell, though in this case the exploitation occurs through URL manipulation rather than script execution. The attack vector typically involves delivering a malicious file: URL through social engineering campaigns or compromised web content, where users inadvertently trigger the directory traversal by visiting the crafted URL. The vulnerability is particularly concerning for Android users as it leverages the mobile platform's file system access patterns and Chrome's integration with the underlying operating system. Security researchers have noted that such path traversal vulnerabilities in browser components often represent high-value targets for attackers due to their ability to bypass traditional web application security controls and access system-level resources directly through browser-based interfaces.
Mitigation strategies for this vulnerability include immediate patching of Chrome to version 50.0.2661.102 or later, which implements proper path normalization and validation routines. Organizations should also consider implementing web application firewalls and content filtering solutions that can detect and block suspicious file: URL patterns. Network administrators should monitor for unusual file access patterns and implement security awareness training to help users identify potentially malicious URLs. Additionally, mobile device management solutions should be configured to enforce automatic updates for Chrome and other browser applications to ensure timely protection against known vulnerabilities. The remediation process should also include reviewing and updating security policies related to mobile browser usage, particularly in enterprise environments where users may have elevated privileges or access to sensitive information through their browser sessions.