CVE-2016-8502 in Yandex
Summary
by MITRE
Yandex Protect Anti-phishing warning in Yandex Browser for desktop from version 15.12.0 to 16.2 could be used by remote attacker for brute-forcing passwords from important web-resource with special JavaScript.
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Analysis
by VulDB Data Team • 05/19/2019
The vulnerability identified as CVE-2016-8502 represents a significant security flaw in Yandex Browser's anti-phishing protection mechanism that existed between versions 15.12.0 and 16.2. This weakness specifically targets the browser's warning system that is designed to protect users from phishing attacks by alerting them when they attempt to access potentially malicious websites. The vulnerability stems from the improper handling of JavaScript code within the anti-phishing warning interface, creating an exploitable condition that allows remote attackers to manipulate the browser's security behavior.
The technical flaw manifests through the browser's insufficient validation of JavaScript content within phishing warning messages. When users encounter a phishing warning, the browser displays a page that contains embedded JavaScript code to enhance the warning experience. However, this implementation failed to properly sanitize or restrict the execution of potentially malicious JavaScript, enabling attackers to inject code that could bypass the intended security protections. This vulnerability operates under the principle of cross-site scripting where the attacker's JavaScript code executes within the browser's security context, potentially allowing for credential theft or session manipulation.
The operational impact of this vulnerability is substantial as it directly undermines the core security functionality that users rely upon for protection. Attackers could exploit this weakness to create convincing phishing warnings that contain malicious JavaScript code designed to capture user credentials from legitimate websites. The attack vector involves crafting specially formatted web pages that trigger the Yandex Browser's anti-phishing warning system while simultaneously embedding JavaScript that performs credential harvesting or session hijacking. This creates a sophisticated attack scenario where the browser's own security features become the vector for compromising user accounts.
The vulnerability aligns with CWE-79 which describes cross-site scripting flaws, and represents a specific implementation weakness in how the browser handles security warning interfaces. From an ATT&CK perspective, this vulnerability maps to technique T1566 for phishing attacks and T1071 for application layer protocol usage, as it leverages the browser's legitimate security features to execute malicious code. The attack demonstrates how security mechanisms can be subverted when proper input validation and execution restrictions are not implemented, creating a false sense of security for users who trust the browser's anti-phishing warnings.
Mitigation strategies for this vulnerability require immediate patching of affected browser versions, as well as implementing proper JavaScript sandboxing within security warning interfaces. Organizations should ensure that all browser security features properly validate and sanitize all user-provided content before execution, particularly within warning and alert systems. The recommended approach includes implementing strict content security policies that prevent execution of unauthorized JavaScript within security contexts, as well as regular security audits of browser components that handle user-facing security notifications. Additionally, users should be educated about the importance of keeping their browsers updated and should avoid clicking on suspicious warnings that appear to be from legitimate security systems, as these may be part of sophisticated attack campaigns targeting the very security features they are meant to protect against.