CVE-2012-3557 in Web Browser
Summary
by MITRE
Opera before 11.65 does not properly restrict the reading of JSON strings, which allows remote attackers to perform cross-domain loading of JSON resources and consequently obtain sensitive information via a crafted web site.
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Analysis
by VulDB Data Team • 03/25/2021
The vulnerability identified as CVE-2012-3557 affects Opera web browsers version 11.64 and earlier, representing a critical security flaw in the browser's handling of JSON data. This issue stems from insufficient validation mechanisms within the browser's JSON parsing implementation that fails to properly enforce cross-origin resource sharing restrictions. The flaw specifically manifests when Opera processes JSON strings, allowing malicious web sites to bypass normal security boundaries that should prevent unauthorized access to sensitive data across different domains.
This vulnerability operates through a sophisticated cross-domain loading mechanism that exploits the browser's JSON parsing behavior. When Opera encounters JSON data from external sources, the implementation does not adequately verify the origin of the data or enforce proper security policies that would normally prevent such cross-domain access. Attackers can craft malicious websites that leverage this weakness to load JSON resources from other domains and extract sensitive information that should be protected by the browser's security model. The vulnerability essentially allows for unauthorized data exfiltration through carefully constructed JSON requests that circumvent normal browser security restrictions.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with a method to gather sensitive data from users' browsing sessions. This could include user credentials, personal information, financial data, or other confidential resources that applications might expose through JSON APIs. The attack vector is particularly dangerous because it requires no special privileges or user interaction beyond visiting a malicious website, making it a significant threat to user privacy and data security. The vulnerability represents a failure in the browser's security model that undermines the fundamental principle of cross-origin resource access controls.
Security professionals should note that this vulnerability aligns with CWE-200, which addresses improper handling of sensitive information, and falls under the broader category of cross-domain access control failures. The ATT&CK framework would categorize this as a technique involving information gathering through web-based attacks, specifically leveraging browser vulnerabilities to extract sensitive data. Organizations should prioritize updating affected Opera installations to version 11.65 or later, as this release includes the necessary patches to address the JSON parsing restrictions. Additionally, implementing proper content security policies and monitoring for unusual JSON loading patterns can help detect potential exploitation attempts. The vulnerability demonstrates the critical importance of proper input validation and cross-origin resource handling in web browsers, particularly in applications that process structured data formats like JSON that are commonly used for data exchange between applications and services.