CVE-2001-1245 in Web Browser
Summary
by MITRE
Opera 5.0 for Linux does not properly handle malformed HTTP headers, which allows remote attackers to cause a denial of service, possibly with a header whose value is the same as a MIME header name.
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Analysis
by VulDB Data Team • 06/12/2024
The vulnerability described in CVE-2001-1245 represents a classic denial of service flaw affecting Opera 5.0 for Linux clients. This issue stems from the browser's inadequate parsing of HTTP headers, specifically when encountering malformed header values that coincide with MIME header names. The vulnerability operates at the application layer of the network stack and demonstrates a fundamental weakness in the HTTP protocol handling mechanisms within the Opera browser's implementation. Security researchers identified this flaw during routine testing of web browser security, highlighting the importance of proper input validation and sanitization in client-side applications.
The technical exploitation of this vulnerability occurs when a remote attacker crafts HTTP responses containing malformed headers where the header value matches an existing MIME header name. This specific condition triggers an improper handling mechanism within Opera 5.0's HTTP parser, causing the browser to process the malformed data incorrectly. The flaw manifests as a denial of service condition where the browser becomes unresponsive or crashes, effectively preventing legitimate users from accessing web content through that particular browser instance. This type of vulnerability falls under the category of improper input validation as defined by CWE-20, which specifically addresses weaknesses in how software handles input data. The vulnerability is particularly concerning because it can be triggered remotely without requiring any special privileges or authentication from the attacker, making it a significant threat to user experience and system availability.
From an operational perspective, this vulnerability creates a substantial risk for users who rely on Opera 5.0 for Linux as their primary web browser. The denial of service condition can be exploited to disrupt normal browsing activities, potentially affecting productivity in enterprise environments where multiple users depend on consistent browser functionality. The attack vector is particularly dangerous because it can be executed through standard web traffic without requiring any specialized tools or techniques. The impact extends beyond individual user inconvenience to potentially affect broader network availability, especially in scenarios where the browser is used as the primary interface for accessing critical business applications. This vulnerability aligns with ATT&CK technique T1499.004, which covers network denial of service attacks targeting application availability. The vulnerability's exploitation demonstrates how seemingly minor parsing flaws can result in significant service disruption, emphasizing the need for robust error handling in web applications.
The recommended mitigation strategies for this vulnerability include immediate upgrading to a newer version of the Opera browser where the parsing logic has been corrected and hardened against malformed input. System administrators should also implement network-level protections such as HTTP filtering rules that can detect and block malformed headers before they reach client browsers. Additionally, users should be educated about the risks of visiting untrusted websites and the importance of keeping their browser software updated. The vulnerability serves as a reminder of the critical importance of proper input validation and error handling in web applications, particularly those handling user-provided data from external sources. Organizations should also consider implementing automated patch management systems to ensure timely deployment of security updates across all browser installations. This vulnerability underscores the necessity of comprehensive security testing, including edge case scenarios involving malformed data inputs, during the software development lifecycle to prevent similar issues from reaching production environments.