CVE-2009-4071 in Web Browser
Summary
by MITRE
Opera before 10.10, when exception stacktraces are enabled, places scripting error messages from a web site into variables that can be read by a different web site, which allows remote attackers to obtain sensitive information or conduct cross-site scripting (XSS) attacks via unspecified vectors.
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Analysis
by VulDB Data Team • 08/28/2021
The vulnerability identified as CVE-2009-4071 represents a critical information disclosure and cross-site scripting flaw in Opera web browsers prior to version 10.10. This security issue stems from improper handling of scripting error messages when exception stacktraces are enabled, creating a dangerous condition where sensitive data can be inadvertently exposed to malicious actors through cross-origin communication channels. The flaw specifically manifests when the browser encounters JavaScript errors during page execution, as it stores error information in variables that should remain isolated to the originating website context.
The technical mechanism behind this vulnerability involves the browser's error reporting system which, when enabled, captures and processes exception stacktraces from web content. In affected Opera versions, these error messages contain sensitive information that gets stored in variables accessible across different origins, violating fundamental web security principles of same-origin policy enforcement. This occurs because the browser fails to properly sanitize or isolate error message content when transferring data between different website contexts, allowing a malicious website to potentially access error information from other domains that may contain sensitive data such as user credentials, session tokens, or internal application details.
The operational impact of this vulnerability is significant as it enables remote attackers to conduct sophisticated cross-site scripting attacks by leveraging the exposed error information. An attacker could craft malicious web pages that, when visited by users with Opera browsers running affected versions, would exploit the information disclosure to gather sensitive data from legitimate websites. This creates a vector for session hijacking, credential theft, and privilege escalation attacks. The vulnerability is particularly dangerous because it operates at the browser level rather than requiring user interaction with malicious content, making it difficult to detect and prevent through traditional user education methods. The attack surface expands when considering that many legitimate websites may contain sensitive information in their error messages, especially those with complex JavaScript applications or those that expose internal debugging information.
This vulnerability aligns with CWE-200, which describes improper information exposure, and CWE-79, which covers cross-site scripting flaws, making it a compound security issue that combines information disclosure with execution vulnerabilities. From an ATT&CK framework perspective, this vulnerability maps to T1059.007 for JavaScript execution and T1566 for phishing attacks, as attackers can leverage the information disclosure to craft more convincing social engineering campaigns. The flaw demonstrates a classic case of inadequate input validation and output sanitization in web browser implementations, where error handling mechanisms fail to properly enforce security boundaries between different origins. Organizations should implement immediate mitigation measures including browser updates to version 10.10 or later, disabling exception stacktrace features when not required for debugging purposes, and implementing proper content security policies to limit the impact of such vulnerabilities. Additionally, security teams should conduct comprehensive assessments of their browser deployment environments to identify and remediate similar issues in other browser vendors that may exhibit comparable behavior patterns.