CVE-2011-2613 in Web Browser
Summary
by MITRE
The Array.prototype.join method in Opera before 11.50 allows remote attackers to cause a denial of service (application crash) via a non-array object that contains initial holes.
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Analysis
by VulDB Data Team • 11/13/2021
The vulnerability identified as CVE-2011-2613 represents a critical flaw in Opera web browser versions prior to 11.50 that affects the Array.prototype.join method implementation. This issue stems from inadequate input validation and error handling within the JavaScript engine's array manipulation functions. The vulnerability specifically targets the join method which is commonly used to convert array elements into a string representation by concatenating them with a specified separator.
The technical exploitation of this vulnerability occurs when a non-array object containing initial holes is passed to the Array.prototype.join method. These initial holes refer to undefined or empty slots within an array-like structure that are not properly handled during the join operation. The flaw arises from the browser's JavaScript engine failing to properly validate whether the object being processed is actually an array before attempting to iterate through its elements. When such malformed objects are processed, the engine encounters unexpected memory states or invalid array indices that trigger internal crashes.
This vulnerability falls under the category of improper input validation and can be classified as CWE-20, which deals with improper input validation in software systems. The operational impact of this vulnerability extends beyond simple application instability as it provides remote attackers with a reliable method to induce denial of service conditions in targeted browsers. Attackers can craft malicious web pages that, when loaded in vulnerable Opera versions, will cause the browser to crash and terminate unexpectedly. This type of attack can be particularly effective in web-based scenarios where users might be tricked into visiting compromised websites or clicking on malicious links that execute the exploit code.
The attack pattern aligns with techniques described in the MITRE ATT&CK framework under the T1499 category, which covers network denial of service attacks. The vulnerability demonstrates how seemingly benign JavaScript operations can be weaponized to create significant operational disruptions. The exploit requires minimal privileges and can be executed through standard web browsing activities, making it particularly dangerous in real-world scenarios. The vulnerability affects not only individual user experiences but also has implications for web application security and browser stability.
Mitigation strategies for this vulnerability involve updating to Opera version 11.50 or later where the fix has been implemented. The fix typically involves enhanced validation checks within the Array.prototype.join method to ensure that only proper array objects are processed, with appropriate error handling for edge cases including objects with initial holes. Security administrators should also implement browser security policies that enforce regular updates and consider deploying additional security layers such as web application firewalls that can detect and block malicious JavaScript patterns. Organizations should also conduct regular security assessments to identify and remediate similar vulnerabilities in their browser environments, as this type of flaw demonstrates the importance of robust input validation in client-side scripting environments.