Vulnerability Note VU#205073

Gesytec Easylon OPC Server fails to properly validate OPC server handles

Overview

The Gesytec Easylon OPC Server contains a vulnerability that may allow a remote attacker to execute arbitary code or cause a denial-of-service condition.

I. Description

OLE for Process Control (OPC) is a specification for a standard set of OLE COM objects used in the process control and manufacturing fields. OPC servers are often used in control systems to consolidate field and network device information.

The Gesytec Easylon OPC Server fails to properly validate server handles. This vulnerability may be triggered by an attacker with access to the server's OPC interface.

II. Impact

An attacker with access to the Gesytec Easylon OPC Server may be able to arbitrarily access server process memory, potentially allowing that attacker to execute arbitrary code or cause a denial of service.

III. Solution

Gesytec has released version 2.3.44 of the Easylon OPC server to correct this vulnerability.

Restrict access to the server

Until a fixed version of the server can be deployed, consider restricting remote access to the server to only trusted hosts. You can restrict the access by using firewalls or by only connecting the server to private networks that are not connected to systems with Internet access.

Critical systems (such as industrial control systems) should either not be connected to corporate networks with Internet connectivity or should be connected in a controlled way. If connecting the control system network to the corporate network is necessary, a firewall should be deployed to monitor and control traffic flow between the two networks.

Systems Affected

Vendor	Status	Date Updated
Gesytec	Vulnerable	10-Sep-2007

References

ftp://ftp.gesytec.de/pub/opc/
http://www.neutralbit.com/en/rd/opctest/
http://www.cpni.gov.uk/docs/re-20050223-00157.pdf
http://www.opcfoundation.org/Default.aspx/01_about/01_whatis.asp?MID=AboutOPC
http://en.wikipedia.org/wiki/OLE_for_process_control

Credit

This vulnerability was reported by NeutralBit.

This document was written by Jeff Gennari and Ryan Giobbi.

Other Information

Date Public	12/14/2007
Date First Published	12/14/2007 08:19:53 AM
Date Last Updated	01/10/2008
CERT Advisory
CVE Name	CVE-2007-4473
Metric	4.50
Document Revision	24