Software Engineering Institute

Microsoft systems use components of Microsoft Outlook Express to render MHTML (MIME Encapsulation of Aggregate HTML) when viewing files. Internet Explorer also relies on the MHTML rendering engine in Outlook Express when displaying web pages.

The MHTML rendering engine in Outlook Express does not validate the type of file being processed. This may lead to web script executing in the Local Computer Zone, which may give remote attackers control of victim systems.

Microsoft has released patches to resolve this issue in Microsoft Security Bulletin MS03-014, Cumulative Patch for Outlook Express (330994).Microsoft also reports that if the patches for MS03-004 have already been applied, only files already present on a target system may be executed.

By exploiting this vulnerability, an attacker may be able to launch programs on a victim's computer in the Local Computer Zone. If an attacker can guess, discover, or know the file path of programs already installed on a victim computer, he may be able to execute arbitrary commands. Additionally, if an attacker can access files he may have downloaded to a victim system, he would be able to execute arbitrary code.

Apply patches for Outlook Express found in MS03-014.