CVE-2016-1656 in Chrome
Summary
by MITRE
The download implementation in Google Chrome before 50.0.2661.75 on Android allows remote attackers to bypass intended pathname restrictions via unspecified vectors.
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Analysis
by VulDB Data Team • 07/25/2022
The vulnerability identified as CVE-2016-1656 represents a significant security flaw in Google Chrome's download handling mechanism on Android devices prior to version 50.0.2661.75. This issue falls under the category of path traversal or directory traversal attacks, where malicious actors can manipulate the download process to access files outside of the intended download directory. The vulnerability stems from insufficient validation of pathname components during the download operation, allowing attackers to craft malicious URLs or download requests that can bypass the intended security boundaries.
The technical implementation flaw manifests in how Chrome processes download requests on Android platforms, specifically in the validation logic that governs file path construction and access control. Attackers can exploit this weakness by constructing specially crafted download URLs or manipulating download parameters to traverse directory structures and potentially access sensitive files that should be restricted. This vulnerability operates at the application level within the browser's download subsystem, leveraging the inherent trust placed in legitimate download operations to execute unauthorized file access patterns. The unspecified vectors referenced in the description suggest multiple attack pathways including but not limited to crafted HTTP headers, manipulated file extensions, or specific URL parameter sequences that can trigger the flawed path resolution logic.
The operational impact of this vulnerability extends beyond simple unauthorized file access, as it can potentially enable attackers to access system files, user data, or application resources that should remain protected. On Android devices, this could allow adversaries to bypass the sandboxing mechanisms that typically isolate browser processes from the underlying operating system and other applications. The implications are particularly severe given that Chrome on Android shares the same security model as desktop versions but operates within the more constrained mobile environment where file system access controls may be less strict. This vulnerability could facilitate further attacks including privilege escalation, data exfiltration, or the execution of malicious code through the exploitation of other vulnerabilities in the system.
Security professionals should consider this vulnerability in the context of the CWE-22 weakness category, which specifically addresses path traversal flaws in software systems. The ATT&CK framework would classify this as a technique involving privilege escalation or lateral movement through application-level vulnerabilities, potentially enabling an attacker to gain access to resources they should not normally be able to reach. Organizations should implement immediate mitigations including updating to Chrome version 50.0.2661.75 or later, which contains the necessary patches to address the pathname restriction bypass. Additionally, network administrators should consider implementing additional monitoring for suspicious download patterns and URL structures that might indicate exploitation attempts, while security teams should conduct comprehensive assessments of their mobile device management policies to ensure proper browser version control and security updates. The vulnerability underscores the importance of robust input validation and proper access control implementation in mobile browser environments where the attack surface is significantly expanded due to the integration of multiple system components and the increased exposure to network-based attacks.