CVE-2011-0682 in Web Browser
Summary
by MITRE
Integer truncation error in opera.dll in Opera before 11.01 allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via an HTML form with a select element that contains a large number of children.
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Analysis
by VulDB Data Team • 10/13/2021
The vulnerability identified as CVE-2011-0682 represents a critical integer truncation flaw within the opera.dll component of the Opera web browser series. This issue affects Opera versions prior to 11.01 and demonstrates how seemingly minor programming errors can result in severe security implications. The vulnerability specifically manifests when processing HTML form elements, particularly select elements that contain an excessive number of child options. The integer truncation error occurs during the parsing and rendering of these complex form structures, creating a scenario where the browser's memory management becomes compromised.
The technical nature of this vulnerability stems from improper handling of integer values during the processing of HTML select elements. When an attacker crafts an HTML form with a select element containing a large number of children, the browser's internal integer variables that track the element count become truncated, leading to incorrect memory allocation calculations. This truncation results in insufficient memory being allocated for the element structure, causing memory corruption that can be exploited to execute arbitrary code or trigger denial of service conditions. The flaw operates at the intersection of buffer management and integer overflow handling, making it particularly dangerous as it can be leveraged for remote code execution.
From an operational perspective, this vulnerability presents significant risks to users of affected Opera versions, as it can be exploited through standard web browsing activities without requiring any special privileges or user interaction beyond visiting a malicious website. The attack vector is particularly concerning because it targets the core rendering engine of the browser, making it difficult to isolate and prevent through traditional security measures. The vulnerability's impact extends beyond simple exploitation to include potential system compromise, as memory corruption can lead to unpredictable behavior including crashes, data corruption, or complete system instability.
The security implications of this vulnerability align with CWE-190, which addresses integer overflow and underflow conditions, and can be mapped to ATT&CK technique T1203, which covers exploitation of remote services through web application vulnerabilities. Organizations affected by this issue should prioritize immediate patching of Opera installations to version 11.01 or later, where the integer truncation error has been resolved through proper integer size validation and memory allocation procedures. Additionally, network administrators should consider implementing web application firewalls and content filtering solutions to prevent access to known malicious sites that might exploit this vulnerability, though such measures provide only partial protection given the nature of the exploit.
The remediation approach for this vulnerability requires comprehensive browser updates across all affected systems, with particular attention to enterprise environments where Opera browser usage may be prevalent. Security teams should also conduct thorough vulnerability assessments to identify any potential exploitation attempts or unauthorized access attempts that might have occurred prior to patching. Regular security monitoring and updated threat intelligence feeds can help detect attempts to exploit this vulnerability, while maintaining updated browser versions serves as the primary defense mechanism against such integer truncation attacks. The incident underscores the importance of rigorous code review processes and proper integer handling in browser security implementations.