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June 25, 2003
Symantec Security Check ActiveX Buffer Overflow


A vulnerability was discovered in a component of Symantec Security Check's online interface. The vulnerability is a buffer overflow in an ActiveX component. An exploit of this vulnerability can lead to unauthorized system access.

Components Affected
Symantec Security Check rufsi.dll dated prior to June 23, 2003.

Symantec was made aware of Symantec Security Check's ActiveX buffer overflow vulnerability on Monday June 23, 2003 through a public posting on the Internet. Since hearing of the exploit Symantec has worked diligently to replace the ActiveX Control on Symantec Security Check. Through Symantec's customer support, we are working with users who may have downloaded the exploited ActiveX Control to remove it from their systems. Although Symantec Security Check is available to both PC and Mac users, this issue only affects PCs.

Symantec Security Check is a free web-based tool that enables users to test their computer's exposure to a wide range of on-line threats. As part of running the check, users may install an ActiveX Control, which remains on the user's system even after the check has completed.

The current ActiveX Control - which can be named Symantec RuFSI Utility Class or Symantec RuFSI Registry Information Class - contains a buffer overflow exploit. The buffer overflow can be exploited when the user with this ActiveX Control visits a malicious website intent on exploiting this vulnerability. The exploit can cause Internet Explorer to crash and/or the execution of arbitrary code on the user's computer.

Symantec Response
Symantec has replaced the current ActiveX Control on the Symantec Security Check website so that new visitors will not be affected by the exploit.

Recent visitors to Symantec Security Check should revisit the site and run a new Security Scan. By running a new scan, the previous ActiveX Control will be replaced by an updated ActiveX Control that fixes the buffer overflow condition.

Advanced users can attempt to delete the ActiveX Control by rebooting and then going into the system folder: %SystemRoot%\Downloaded Program Files\ and delete "rufsi.dll". This must be done by using the command prompt and the user must not be on the Symantec Security Check site at the time.

A removal tool has been developed and can be found here.

Symantec takes the security and proper functionality of our products very seriously. As founding members of the Organization for Internet Safety (OISafety), Symantec supports and follows the principles of responsible disclosure. Symantec also subscribes to the vulnerability disclosure guidelines outlined by the National Infrastructure Advisory Council (NIAC).

Please contact secure@symantec.com if you feel you have discovered a security issue in a Symantec product. A Symantec Product Security team member will contact you regarding your submission. Symantec strongly recommends using encrypted email for reporting vulnerability information to secure@symantec.com. The Symantec Product Security PGP key can be found at the end of this message.

Symantec has developed a Product Vulnerability Response document outlining the process we follow in addressing suspected vulnerabilities in our products. This document is available below.

PDF Symantec Vulnerability Response Policy PGP Symantec Product Vulnerability Management PGP Key

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The information in the advisory is believed to be accurate at the time of publishing based on currently available information. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. Neither the author nor the publisher accepts any liability for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information.

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Last modified on: Monday, 25-Oct-2004 15:08:25 PDT