Vulnerability Note VU#281977

Quiksoft EasyMail SMTP ActiveX control stack buffer overflow vulnerabilities

Overview

The Quiksoft EasyMail SMTP ActiveX control contains multiple stack buffer overflow vulnerabilities, which could allow a remote, unauthenticated attacker to execute arbitrary code on a vulnerable system.

I. Description

Quiksoft EasyMail Objects is a set of ActiveX controls that provides email functionality, including SMTP, POP3, and IMAP4. The EasyMail SMTP ActiveX control, which is provided by emsmtp.dll, contains multiple stack buffer overflow vulnerabilities.

This control is bundled with several applications, including Earthlink internet access software. Exploit code for this vulnerability is publicly available.

II. Impact

A remote, unauthenticated attacker may be able to execute arbitrary code on a vulnerable system with privileges of the user.

III. Solution

We are currently unaware of a practical solution to this problem. Please consider the following workarounds

Disable the Quiksoft EasyMail ActiveX control in Internet Explorer

The vulnerable ActiveX control can be disabled in Internet Explorer by setting the kill bit for the following CLSID:

{68AC0D5F-0424-11D5-822F-00C04F6BA8D9}

More information about how to set the kill bit is available in Microsoft Support Document 240797. Alternatively, the following text can be saved as a .REG file and imported to set the kill bit for this control:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINESOFTWAREMicrosoftInternet ExplorerActiveX Compatibility{68AC0D5F-0424-11D5-822F-00C04F6BA8D9}]
"Compatibility Flags"=dword:00000400

Disable ActiveX

Disabling ActiveX controls in the Internet Zone (or any zone used by an attacker) appears to prevent exploitation of this and other ActiveX vulnerabilities. Instructions for disabling ActiveX in the Internet Zone can be found in the "Securing Your Web Browser" document.

Systems Affected

Vendor	Status	Date Updated
Earthlink	Vulnerable	29-Aug-2007
Gate Comm Software	Vulnerable	29-Aug-2007
Quiksoft	Vulnerable	29-Aug-2007

References

http://www.cert.org/tech_tips/securing_browser/#Internet_Explorer
http://www.quicksoftcorp.com/objects/
http://www.quicksoftcorp.com/clients/whouses.asp

Credit

This vulnerability was reported by Will Dormann of the CERT/CC. The vulnerability was also independently discovered and publicly disclosed by rgod.

This document was written by Will Dormann.

Other Information

Date Public	08/27/2007
Date First Published	08/29/2007 03:15:22 PM
Date Last Updated	08/30/2007
CERT Advisory
CVE Name
Metric	25.82
Document Revision	5