CVE-2015-6045 in Internet Explorer
Summary
by MITRE
Use-after-free vulnerability in the CElement object implementation in Microsoft Internet Explorer 11 allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via crafted JavaScript that improperly interacts with use of the Cascading Style Sheets (CSS) empty-cells property for a TABLE element, aka "Internet Explorer Memory Corruption Vulnerability."
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Analysis
by VulDB Data Team • 06/27/2022
The CVE-2015-6045 vulnerability represents a critical use-after-free flaw in Microsoft Internet Explorer 11's implementation of the CElement object within the browser's rendering engine. This vulnerability specifically targets the handling of the CSS empty-cells property when applied to TABLE elements, creating a scenario where memory corruption can occur through malicious JavaScript execution. The flaw arises from improper memory management during the processing of CSS properties that control how empty cells in tables are rendered, allowing attackers to manipulate memory contents through carefully crafted web pages.
The technical exploitation of this vulnerability occurs when Internet Explorer processes a web page containing malicious JavaScript code that manipulates the empty-cells CSS property of table elements. The underlying issue stems from a classic use-after-free condition where memory allocated to a CElement object is freed but subsequently referenced by JavaScript code that continues to interact with the now-invalid memory location. This memory corruption can be leveraged to execute arbitrary code with the privileges of the user running the browser, or alternatively cause a denial of service through application crash. The vulnerability is particularly dangerous because it can be triggered through standard web browsing activities without requiring any special user interaction beyond visiting a malicious website.
From an operational impact perspective, this vulnerability poses significant risks to enterprise environments where Internet Explorer 11 remains in use, as it can be exploited through drive-by downloads or compromised websites. The vulnerability's exploitation vector is particularly concerning because it leverages standard web technologies that are commonly encountered in everyday browsing scenarios. Security researchers have classified this as a remote code execution vulnerability, with potential for privilege escalation depending on the user context. The flaw affects Microsoft Internet Explorer 11 specifically, though similar issues may exist in other browser versions that share the same underlying rendering engine components.
The vulnerability aligns with CWE-416, which describes the use-after-free condition as a common memory safety issue where a pointer is used after the memory it points to has been freed. This weakness is particularly relevant in browser environments where complex object models interact with JavaScript engines and CSS parsers. The ATT&CK framework categorizes this as a technique for code execution through memory corruption vulnerabilities, falling under the broader category of exploitation of memory corruption flaws. Organizations should consider this vulnerability as part of their broader browser security posture, particularly when Internet Explorer 11 remains in production environments where it cannot be immediately replaced with modern browser alternatives. Mitigation strategies include immediate patch deployment, browser hardening measures, and network-based protections such as content filtering and web application firewalls to prevent exploitation of this vulnerability in environments where immediate patching is not feasible.