CVE-2011-0684 in Web Browser
Summary
by MITRE
Opera before 11.01 does not properly handle redirections and unspecified other HTTP responses, which allows remote web servers to obtain sufficient access to local files to use these files as page resources, and consequently obtain potentially sensitive information from the contents of the files, via an unknown response manipulation.
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Analysis
by VulDB Data Team • 10/13/2021
This vulnerability in Opera browsers prior to version 11.01 represents a critical information disclosure flaw that exploits improper handling of HTTP redirections and response processing. The vulnerability stems from the browser's insufficient validation mechanisms when processing HTTP responses from remote servers, creating a pathway for malicious actors to manipulate response handling and gain unauthorized access to local file resources. The flaw operates by leveraging the browser's failure to properly sanitize or validate HTTP response data, particularly during redirection sequences, which can lead to unintended file access patterns. This weakness falls under the category of improper input validation and weak response handling, aligning with CWE-20 and CWE-22 security principles that address improper input validation and path traversal vulnerabilities.
The technical implementation of this vulnerability allows remote web servers to manipulate HTTP responses in such a way that they can reference local files on the victim's system. When Opera processes these manipulated responses, it fails to properly isolate the local file access from the web context, enabling the remote server to effectively serve local files as web page resources. This creates a scenario where sensitive information contained within local files can be extracted and transmitted to the remote server without proper authorization. The vulnerability demonstrates a fundamental flaw in the browser's security model regarding resource access control and response handling, particularly when dealing with HTTP redirects and various response types that should normally be processed securely.
The operational impact of this vulnerability extends beyond simple information disclosure, as it enables attackers to potentially access sensitive local files that may contain personal information, system configuration details, or application data. Attackers can leverage this vulnerability to perform reconnaissance activities, gather intelligence about the victim's system, and potentially escalate their privileges or access additional resources. The attack vector is particularly concerning because it requires minimal user interaction beyond visiting a malicious website, making it a significant threat in phishing campaigns or targeted attacks. This vulnerability directly impacts the principle of least privilege and demonstrates how improper HTTP response handling can compromise the security boundaries between local system resources and web-based access.
Mitigation strategies for this vulnerability should focus on updating to Opera version 11.01 or later, which contains the necessary patches to properly handle HTTP redirections and responses. Organizations should implement network-level protections such as web application firewalls and content filtering systems to detect and block suspicious HTTP response patterns. Browser security configurations should be hardened to restrict local file access and implement additional validation layers for HTTP responses. The vulnerability highlights the importance of proper input sanitization and response validation, aligning with ATT&CK techniques that emphasize credential access and reconnaissance through web-based attacks. Security teams should monitor for exploitation attempts and implement comprehensive logging of HTTP traffic to detect potential abuse of this vulnerability. Regular security assessments and vulnerability scanning should include checks for outdated browser versions that may still be susceptible to this class of information disclosure attacks.