CVE-2017-17859 in Internet Browser
Summary
by MITRE
Samsung Internet Browser 6.2.01.12 allows remote attackers to bypass the Same Origin Policy, and conduct UXSS attacks to obtain sensitive information, via vectors involving an IFRAME element inside XSLT data in one part of an MHTML file. Specifically, JavaScript code in another part of this MHTML file does not have a document.domain value corresponding to the domain that is hosting the MHTML file, but instead has a document.domain value corresponding to an arbitrary URL within the content of the MHTML file.
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Analysis
by VulDB Data Team • 12/18/2019
This vulnerability in Samsung Internet Browser 6.2.01.12 represents a critical security flaw that undermines the fundamental Same Origin Policy protection mechanism. The vulnerability arises from improper handling of cross-origin resource sharing within MHTML files, specifically when IFRAME elements are embedded within XSLT data sections. The attack vector exploits the browser's failure to properly enforce origin restrictions when processing nested content within compound document formats, creating a pathway for malicious actors to bypass essential security boundaries.
The technical implementation of this flaw involves a sophisticated manipulation of document domain properties within the browser's rendering engine. When an MHTML file contains an IFRAME element embedded within XSLT data, the browser incorrectly sets the document.domain value to match an arbitrary URL found within the MHTML content rather than maintaining the proper domain context of the hosting origin. This misconfiguration allows JavaScript code executed in one part of the MHTML file to access resources and data from another part that would normally be restricted by cross-origin policies. The vulnerability specifically targets the browser's handling of nested document contexts and demonstrates a failure in origin validation mechanisms.
The operational impact of this vulnerability is severe as it enables unauthorized information disclosure through UXSS (User eXecution of Stored XSS) attacks. Attackers can craft malicious MHTML files that, when opened in the vulnerable browser, allow remote code execution and data exfiltration from the user's session. This creates a persistent threat where users' sensitive information, including cookies, session tokens, and personal data, becomes accessible to malicious actors. The vulnerability is particularly dangerous because it operates at the browser's core rendering layer, making it difficult to detect and mitigate through traditional security measures.
This vulnerability maps to CWE-16 (Configuration) and CWE-94 (Code Injection) categories, representing both configuration flaws in the browser's security model and code execution vulnerabilities. The attack pattern aligns with ATT&CK technique T1059.007 (Command and Scripting Interpreter: JavaScript) and T1566 (Phishing) as attackers can leverage this vulnerability through malicious web content. The exploitation requires minimal user interaction beyond visiting a malicious webpage, making it particularly effective for social engineering campaigns. Organizations should implement browser hardening measures, disable MHTML file processing, and ensure timely updates to prevent exploitation of this vulnerability.
The root cause lies in the browser's inadequate handling of document context switching within compound document formats, specifically failing to maintain proper security boundaries when processing nested IFRAME elements within XSLT sections. This flaw demonstrates the complexity of modern browser security architectures and the challenges in maintaining consistent security policies across different content types and rendering contexts. The vulnerability underscores the importance of comprehensive security testing for browser vendors and highlights the need for robust cross-origin policy enforcement mechanisms.