CVE-2015-2425

What Is Internet Explorer?

Internet Explorer (IE) was Microsoft's web browser from 1995 through its discontinuation in June 2022. At its peak, IE held over 90% browser market share, making IE vulnerabilities the highest-impact browser attack surface. IE's rendering engine (Trident/MSHTML) and scripting engines (JScript, VBScript) were the target of continuous exploitation — the browser was the primary entry point for both APT attacks and mass criminal exploitation via exploit kits throughout the 2000s and 2010s.

Overview

CVE-2015-2425 is a memory corruption vulnerability in Microsoft Internet Explorer that allows remote attackers to execute arbitrary code or cause a denial-of-service when a user visits a specially crafted web page. The vulnerability involves out-of-bounds write memory corruption in the IE MSHTML rendering engine. Patched in MS15-065 (July 14, 2015), the same cumulative IE update that also addressed CVE-2015-2419 (JScript memory corruption). See also related IE vulnerabilities from this period: CVE-2015-2419 and CVE-2015-2502.

Affected Versions

Fixed in MS15-065 (July 2015 cumulative IE update).

Technical Details

Root Cause: MSHTML Memory Corruption

CVE-2015-2425 involves out-of-bounds write memory corruption in Internet Explorer's MSHTML rendering engine (the component that parses and renders HTML, CSS, and DOM content). Processing a specially crafted web page causes MSHTML to write beyond the bounds of an allocated buffer, corrupting adjacent heap memory.

IE MSHTML memory corruption vulnerabilities of this class are exploited through:

1. Heap grooming — allocating and freeing specific objects to arrange the heap so the overflow corrupts a target object
2. Information leak — combining with an ASLR bypass (e.g., CVE-2015-0071) to learn the memory layout
3. ROP chain — building a return-oriented programming chain using known addresses to defeat DEP
4. Code execution — the combined exploit achieves reliable code execution

Attack Characteristics

Discovery

Reported to Microsoft and patched in MS15-065 (July 2015 cumulative IE update), which addressed approximately 25 vulnerabilities across IE 7–11.

Exploitation Context

• Exploit kit integration: IE memory corruption vulnerabilities were the primary payload in commercial exploit kits in 2015; July 2015 IE bugs entered Angler and Nuclear kit rotations as n-day exploits following patch release
• APT drive-by attacks: Nation-state actors used IE vulnerabilities in drive-by campaigns — compromising sites frequented by target organizations and exploiting visiting IE users
• Retired product risk: Internet Explorer was retired June 15, 2022 with no further security updates; any remaining IE installation is permanently exposed to the full catalog of known IE vulnerabilities
• CISA KEV (2022): Added May 2022

Remediation

1. Apply MS15-065 (July 2015 cumulative IE update).

2. Retire Internet Explorer — IE reached end-of-life June 15, 2022. Migrate all users to Microsoft Edge (Chromium), Chrome, or Firefox.

3. Enforce Edge or Chrome as default browser via Group Policy — prevents IE from being used as the default browser.

4. Block IE via AppLocker or WDAC if migration cannot be completed immediately.