1. Symantec/
  2. Security Response/
  3. Attack Signatures/
  4. HTTP British Telecom Webhelper ActiveX BO

HTTP British Telecom Webhelper ActiveX BO

Severity: High

This attack could pose a serious security threat. You should take immediate action to stop any damage or prevent further damage from happening.

Description

This signature detects attempts to exploit buffer overflow vulnerability by passing long arguments to multiple methods of British Telecommunications Consumer Webhelper ActiveX control.

Additional Information

The British Telecommunications Consumer Webhelper ActiveX control is a user-registration application for British Telecommunications customers.

The application is prone to multiple buffer-overflow vulnerabilities because it fails to bounds-check user-supplied data before copying it into an insufficiently sized buffer.

These issues occur when an excessive amount of data is passed to the following functions of the 'btwebcontrol.dll' ActiveX control library:

Download() : when more than 4016 characters are sent through the fourth parameter.
DownloadDialer() : when more than 4016 characters are sent through the fourth parameter.
ChangeSecondaryPassword() : when more than 982 characters are processed.
GetICMVersion() : when more than 260 characters are processed.
GetICMAAffinity() : when more than 260 characters are processed.
IsICMActive() : when more than 128 characters are processed.
ChangeSecondaryPasswordEx() : when more than 982 characters are processed.
ChangeMode() : when more than 261 characters are sent through the second parameter.

These issues reside in the ActiveX control with CLSID: EC5A4E7B-02EB-451D-B310-D5F2E0A4D8C3.

Successfully exploiting these issues allows remote attackers to execute arbitrary code in the context of the application using the ActiveX control (typically Internet Explorer). Failed exploit attempts likely result in denial-of-service conditions.

Versions of British Telecommunications Consumer Webhelper ActiveX Control prior to 2.0.0.8 are vulnerable to these issues.

Affected

  • British Telecommunications Consumer webhelper 2.0.0.7, 2.0.0.8

Response

The vendor has released version 2.0.0.8 to address these issues; please see the references for details.
  • Twitter
  • Facebook
  • LinkedIn
  • Google+
  • YouTube