CVE-2011-4690 in Web Browser
Summary
by MITRE
Opera 11.60 and earlier does not prevent capture of data about the times of Same Origin Policy violations during IFRAME loading attempts, which makes it easier for remote attackers to determine whether a document exists in the browser cache via crafted JavaScript code.
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Analysis
by VulDB Data Team • 01/16/2018
The vulnerability identified as CVE-2011-4690 affects Opera versions 11.60 and earlier, exposing a critical flaw in how the browser handles Same Origin Policy (SOP) violations during IFRAME loading operations. This issue represents a sophisticated timing attack vector that leverages the browser's internal mechanisms for tracking SOP violations to infer cached document states. The vulnerability operates through the browser's security model by capturing timing data related to cross-origin resource access attempts, specifically when IFRAME elements attempt to load content from different origins.
The technical exploitation of this vulnerability relies on the fact that Opera's implementation of SOP violation tracking creates observable timing differences when attempting to load resources that are either present or absent in the browser cache. When a malicious script attempts to load an IFRAME from a different origin, the browser records the time required to process the SOP violation, and this timing information becomes accessible to JavaScript code. Attackers can craft JavaScript code that measures these timing variations to determine whether specific documents exist in the browser cache, effectively creating a cache probing mechanism that bypasses normal security boundaries.
This vulnerability directly relates to CWE-200, which addresses "Information Exposure Through Timing Discrepancies," and represents a classic example of how seemingly benign browser functionality can be weaponized for information disclosure attacks. The operational impact of this vulnerability extends beyond simple cache probing, as it provides attackers with significant reconnaissance capabilities that could be combined with other attack vectors to build more sophisticated exploitation strategies. The timing-based information leakage creates a covert channel that allows attackers to map cache states and potentially infer the presence of sensitive documents or resources that should remain hidden.
The attack surface is particularly concerning given that Opera's user base at the time included numerous enterprise and privacy-conscious users who relied on the browser's security features. This vulnerability could enable attackers to perform cache-based reconnaissance against targeted users, potentially identifying cached sensitive documents, login pages, or other resources that could be used in subsequent attacks. The implications extend to privacy concerns as this mechanism could reveal browsing history patterns or document access behaviors that users expect to remain private.
Mitigation strategies for this vulnerability should focus on implementing proper timing randomization in SOP violation handling mechanisms, ensuring that timing information does not leak across security boundaries. Browser vendors should consider implementing consistent processing delays for cross-origin resource attempts regardless of cache state, and should avoid exposing timing data through JavaScript APIs. The recommended approach aligns with ATT&CK technique T1083, which addresses "File and Directory Discovery," as this vulnerability enables similar reconnaissance capabilities through timing-based cache probing rather than direct file system access. Security updates should include modifications to how browsers handle IFRAME loading and SOP violations, ensuring that timing variations cannot be reliably measured or exploited by malicious JavaScript code.