CVE-2010-2661 in Web Browser
Summary
by MITRE
Opera before 10.54 on Windows and Mac OS X, and before 10.60 on UNIX platforms, does not properly restrict access to the full pathname of a file selected for upload, which allows remote attackers to obtain potentially sensitive information via unspecified DOM manipulations.
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Analysis
by VulDB Data Team • 09/20/2021
This vulnerability exists in Opera web browsers across multiple operating systems including Windows, Mac OS X, and UNIX platforms. The issue stems from insufficient input validation and access control mechanisms within the browser's file upload handling functionality. When users attempt to upload files through web forms, the browser fails to properly sanitize or restrict the file path information that gets exposed to remote attackers. This weakness allows malicious actors to manipulate the Document Object Model through unspecified DOM manipulations to extract potentially sensitive file path information from the local system. The vulnerability affects versions prior to Opera 10.54 on Windows and Mac OS X platforms, and versions prior to Opera 10.60 on UNIX systems, indicating a widespread issue that impacted a significant portion of the browser user base during that time period.
The technical flaw represents a classic information disclosure vulnerability that operates at the application layer of the network stack. The root cause lies in the browser's improper handling of file path resolution and access control during file upload operations. When a user selects a file for upload, the browser should only expose minimal necessary information about the file to the web application while maintaining proper isolation between the local file system and remote web content. However, Opera's implementation allows attackers to leverage DOM manipulation techniques to access the complete file path, which can include directory structures, system paths, and potentially sensitive location information. This vulnerability falls under the CWE-200 category for exposure of sensitive information and aligns with ATT&CK technique T1083 for discovering file and directory permissions, as it exposes information about local file system structures. The flaw essentially creates an information leak channel that bypasses normal browser security boundaries.
The operational impact of this vulnerability extends beyond simple information disclosure, as the exposed file path information can provide attackers with valuable reconnaissance data for subsequent exploitation attempts. An attacker who successfully exploits this vulnerability could gain knowledge about the target system's directory structure, file locations, and potentially sensitive system information that could aid in planning more sophisticated attacks. The exposure of full file paths could reveal system-specific information such as user home directories, application installation paths, and other structural details that might be leveraged to craft targeted attacks against the system. This vulnerability particularly affects environments where Opera browsers are used for web browsing, as it could be exploited through malicious websites or web applications that are designed to probe for such information disclosure weaknesses. The impact is especially concerning in enterprise environments where browser security is critical for protecting sensitive corporate data and maintaining system integrity.
The recommended mitigations for this vulnerability include immediate upgrade to Opera versions 10.54 or later for Windows and Mac OS X platforms, and version 10.60 or later for UNIX platforms, where the issue has been addressed through proper input validation and access control mechanisms. Organizations should also implement network-based security controls such as web application firewalls that can detect and block suspicious file path information disclosure attempts. Browser security configurations should be reviewed to ensure that file upload functionality is properly restricted and that appropriate security policies are enforced. Additionally, security awareness training for users can help prevent accidental exposure to malicious websites that might exploit this vulnerability. The fix implemented by Opera developers likely involved strengthening the DOM manipulation restrictions during file upload operations and ensuring that only appropriate file path information is exposed to web applications, thereby closing the information leak channel that was previously available to remote attackers.