Security Concerns Prompt Major Browser Changes
Microsoft has implemented significant changes to the Microsoft Edge browser’s Internet Explorer compatibility mode following what the company describes as “credible reports” of security exploits. According to reports from Microsoft’s Browser Vulnerability Research team, attackers were leveraging IE Mode’s backward compatibility components to bypass built-in security protections in Windows devices.
Exploitation Technique Details
The report states that threat actors combined social engineering tactics with zero-day vulnerabilities in Internet Explorer’s legacy JavaScript engine. Sources indicate that attackers used what’s known as the Chakra engine – the core component behind Internet Explorer‘s scripting capabilities – to execute arbitrary code on targeted machines.
Analysts suggest the attack method involved disguising malicious pages as legitimate websites. Victims would encounter an on-screen prompt designed as a flyout interface element that instructed them to reload the page in IE Mode. Once reloaded, the browser session would run in a less secure environment that retained compatibility with older web technologies, creating an opening for exploitation.
Expanding Beyond Browser Compromise
The security incident reportedly extended beyond browser-level access. According to Microsoft’s findings, hackers leveraged a secondary exploit to elevate privileges beyond Edge’s confines, granting them total control of affected devices. This level of access enabled intruders to deploy malware, move laterally within networks, or exfiltrate sensitive data according to the technical analysis.
Security experts consider this exploitation significant because it undermines the protective design of modern Chromium-based web browsers. By forcing sessions into IE Mode, attackers reportedly bypassed multiple layers of sandboxing and other built-in safeguards that typically limit access to the operating system.
Microsoft’s Response and User Impact
In response to verified active exploitation, Microsoft has removed multiple features that previously made entering IE Mode straightforward. The dedicated toolbar button, right-click context option, and hamburger menu item have all been eliminated from Edge to prevent accidental or manipulated use of the older browsing framework.
According to the company’s official documentation, users who still require IE Mode for legacy websites must now enable it manually through Edge’s settings. This involves navigating to Settings > Default Browser and switching the “Allow sites to be reloaded in Internet Explorer mode” option to “Allow,” then adding each approved website to a compatibility list before manually reloading the page.
Security Through Intentional Action
Microsoft designed these changes to reinforce user awareness and reduce exposure to risks associated with obsolete code paths. The company explained that requiring explicit user action to enable IE Mode for specific pages introduces friction that makes exploitation considerably more difficult.
“This approach ensures that the decision to load web content using legacy technology is significantly more intentional,” Microsoft wrote in their technical report. Analysts suggest the additional steps required to add a site to the compatibility list create a substantial barrier even for determined attackers.
Broader Security Context
This security update comes amid ongoing concerns about legacy technology vulnerabilities across the tech industry. Similar attention to legacy system security has emerged in other sectors, including storage devices like Western Digital’s 32TB Ultrastar drive and even medical technology developments such as the universal kidney creation by researchers. Meanwhile, financial markets continue to navigate technological transitions, as seen in mixed Asia-Pacific market performance amid broader technological shifts.
The IE Mode changes reflect Microsoft’s ongoing effort to balance backward compatibility with modern security requirements, particularly as threat actors increasingly target legacy system vulnerabilities.
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