Microsoft Internet Explorer Cumulative Security Update (MS15-124): Patch Details and System Impact

I’ve seen firsthand how these patches prevent attackers from exploiting browser weaknesses to gain system control. Remote code execution means hackers could run malicious software on your machine without your knowledge. This update was particularly important for enterprise environments where legacy IE versions were still widely used. 🔥

Security Vulnerabilities Fixed in MS15-124 Update

This patch addressed 31 distinct vulnerabilities in Internet Explorer, with 26 rated Critical by Microsoft’s severity system. The most dangerous were memory corruption flaws that allowed attackers to execute arbitrary code if users visited compromised websites. These exploits typically used maliciously crafted HTML elements or JavaScript to trigger buffer overflows in the browser’s rendering engine.

One notable vulnerability (CVE-2015-2419) involved how IE handled VBScript memory allocation. Attackers could corrupt system memory through specially designed web pages, gaining the same user rights as the current account. For systems with admin privileges, this meant complete system takeover. The update reworked memory handling routines and added bounds checking to prevent such overflows.

Other patched issues included information disclosure bugs that let websites access data from other domains, and elevation of privilege vulnerabilities that could bypass IE’s Protected Mode. These were particularly risky in corporate networks where users often had elevated permissions. The cumulative nature meant it included all previous fixes, so systems only needed this single update.

Enterprise environments were the primary concern, as many still relied on IE8-IE11 for legacy applications. The update’s release in August 2015 came during a period when browser-based attacks were surging, making it one of the most important patches of that year. 🔥

What made these vulnerabilities especially dangerous was their potential for drive-by downloads. Users didn’t need to click anything—simply viewing a malicious ad on a legitimate site could trigger the exploit. This update closed those silent attack vectors completely.

How to Install Internet Explorer MS15-124 Patch

For most users, the simplest method is using Windows Update. Open your Control Panel, navigate to Windows Update, and click Check for updates. If available, MS15-124 will appear as a critical security update. Select it and choose Install updates to begin the process automatically. 🔥

Enterprise admins should use Windows Server Update Services (WSUS) to deploy this patch across multiple machines. First, synchronize your WSUS server, then approve the update for relevant computer groups. You can schedule the installation during off-hours to minimize disruption to workflow.

After installation, verify the update succeeded by checking Installed Updates in Control Panel. Look for KB3088903 (the specific knowledge base number for MS15-124). If you encounter issues, run Microsoft’s System Update Readiness Tool to repair potential Windows Update components.

For manual installation, download the appropriate .msu or .exe package from Microsoft’s Update Catalog. Run the installer with admin rights, then restart your system. Remember: always back up critical data before applying security patches, especially in production environments. ✨