CVE-2013-3897

What is Microsoft Internet Explorer?

Microsoft Internet Explorer was the dominant enterprise browser through the 2010s, with significant deployment in defense, government, and technology sectors. IE's CDisplayPointer class represents a cursor/selection position within the rendered HTML document. Use-after-free vulnerabilities in display-related classes like CDisplayPointer are triggered by JavaScript DOM manipulation sequences that cause the object to be freed while a reference remains in the rendering pipeline.

Overview

CVE-2013-3897 is a use-after-free vulnerability (CWE-416) in Microsoft Internet Explorer 8 and 9 in the CDisplayPointer class. A crafted web page can cause IE to free a CDisplayPointer object while the rendering engine retains a live reference — when IE subsequently accesses the freed object, memory corruption occurs, enabling arbitrary code execution. This zero-day was exploited in Operation Ephemeral Hydra, a targeted water-holing campaign against defense contractor and policy organization websites.

Microsoft patched this in MS13-088 (November 2013 Patch Tuesday).

Affected Versions

Technical Details

IE's CDisplayPointer class tracks text cursor and selection positions within the rendered document model. The use-after-free occurs via a sequence of JavaScript DOM manipulations:

1. A CDisplayPointer object is created as IE prepares for or begins rendering a portion of the document
2. JavaScript operations (attribute changes, element removals, or layout modifications) trigger premature freeing of the CDisplayPointer object
3. The rendering engine continues to hold a reference to the freed object
4. A subsequent rendering operation dereferences the freed pointer, triggering the use-after-free

Exploitation: With a JavaScript heap spray filling the freed allocation with attacker-controlled data before the dangling pointer is dereferenced, the virtual function call table pointer is redirected to shellcode or a ROP chain. The result is arbitrary code execution as the IE browser user.

IE 8 and 9 specificity: Unlike many IE vulnerabilities that affected broad version ranges, CVE-2013-3897 was specific to IE 8 and 9. In late 2013, IE 8 was the most common version in enterprise and government environments (default on Windows XP and Windows 7), making this high-value for targeted attacks against those sectors.

Discovery

Identified in the context of the Operation Ephemeral Hydra attacks by FireEye researchers in October 2013. The zero-day was being actively exploited against carefully selected targets before Microsoft was notified, making this a true in-the-wild zero-day at the time of CVE publication.

Exploitation Context

CISA confirmed exploitation in the wild. Operation Ephemeral Hydra was an APT campaign (attributed to Chinese state-sponsored actors) that:

• Water-holed websites frequented by defense contractor employees, aerospace industry workers, and foreign policy professionals
• Served the IE exploit selectively to visiting IE 8 and 9 users, avoiding detection by security researchers
• Delivered a custom RAT payload for persistent access and data exfiltration

The operation ran concurrently with Operation DeputyDog (CVE-2013-3893 targeting Japanese organizations) — both discovered and reported by FireEye in late 2013, suggesting coordinated APT activity exploiting multiple simultaneous IE zero-days.

Remediation

Internet Explorer reached end-of-life on June 15, 2022. Organizations should:

1. Uninstall or disable Internet Explorer — replace with Microsoft Edge
2. For historical remediation: MS13-088 (November 2013) patches CVE-2013-3897 for IE 8 and 9
3. Disable IE via Group Policy and audit remaining IE installations across the enterprise
4. Review web proxy logs for patterns of selective exploit delivery (e.g., only IE user-agents receiving unusual JavaScript payloads from compromised sites)