Software Engineering Institute

Microsoft Hyperlink Object Library (HLINK.DLL)

The Hyperlink Object Library provides interfaces for handling hyperlinks. More information is available in the Microsoft Hyperlinks Guide.

The Problem

There is a stack-based buffer overflow in the Microsoft Hyperlink Object Library. The overflow may be triggered by clicking a specially crafted hyperlink. Note that any program that links to the HLINK.DLL library may be vulnerable, including Microsoft Office applications.

Exploit code for this vulnerability is publicly available.

By convincing a user to access a specially crafted hyperlink, an attacker could execute arbitrary code with the privileges of the attacked user. If the user is logged in with administrative privileges, the attacker could take complete control of a vulnerable system.

Apply update from Microsoft
This issue is addressed in Microsoft Security Bulletin MS06-050.

Do not follow unsolicited hyperlinks

Do not click on unsolicited links received in email or embedded in Office documents. Exploitation of this vulnerability requires a user to click a specially crafted link. By only accessing hyperlinks from known and trusted sources, the chances of exploitation are reduced.