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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2013.1079 IOServer Master Station Improper Input Validation 7 August 2013 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: IOServer Master Station Publisher: US-CERT Operating System: Windows Impact/Access: Denial of Service -- Remote/Unauthenticated Resolution: Patch/Upgrade CVE Names: CVE-2013-2790 Original Bulletin: http://ics-cert.us-cert.gov/advisories/ICSA-13-213-03 - --------------------------BEGIN INCLUDED TEXT-------------------- Advisory (ICSA-13-213-03) IOServer Master Station Improper Input Validation Original release date: August 01, 2013 | Last revised: August 05, 2013 OVERVIEW Adam Crain of Automatak and independent researcher Chris Sistrunk have identified an improper input validation vulnerability in the IOServer DNP3 Driver on the master station. IOServer has produced a new version that mitigates this vulnerability. The researchers have tested the new version to validate that it resolves the vulnerability. This vulnerability could be exploited remotely. AFFECTED PRODUCTS The following IOServer product versions are affected: IOServer's Beta2041.exe, and IOServer's versions older than driver19.exe. IMPACT The master station device can be put into an infinite loop by sending a specially crafted TCP packet, known as "TCP Connection Hijacking." The device must be manually restarted to recover from the loop condition. Impact to individual organizations depends on many factors that are unique to each organization. ICS-CERT recommends that organizations evaluate the impact of this vulnerability based on their operational environment, architecture, and product implementation. BACKGROUND IOServer is a New Zealand-based company that maintains users in several countries around the world, including the UK, Canada, New Zealand, Australia, Austria, France, Germany, Netherlands, Italy, India, Czech Republic, China, Singapore, South Korea, South Africa, and Brazil. IOServer is a Windows-based (WindowsNT/95/98/ME/2000/2003/XP/2008/7) OPC Server that allows OPC clients such as human-machine interface and supervisory control and data acquisition systems to exchange plant floor data with programmable logic circuits. According to IOServer, the affected products are deployed across multiple sectors including manufacturing, building automation, oil and gas, water and wastewater, electric utilities, and others. VULNERABILITY CHARACTERIZATION VULNERABILITY OVERVIEW IMPROPER INPUT VALIDATION.[a] The IOServer driver does not validate or incorrectly validates input on the master server on Port 20000/TCP that can affect the control flow or data flow of a program. When this software does not validate input properly, an attacker is able to craft the input in a form that is not expected by the rest of the application. This will lead to parts of the system receiving unintended input, which may result in altered control flow or arbitrary control of a resource. As a result, the IOServer enters an infinite loop condition without an exit. The system must then be restarted manually. CVE-2013-2790[b] has been assigned to this vulnerability. A CVSS v2 base score of 7.1 has been assigned; the CVSS vector string is (AV:N/AC:M/Au:N/C:N/I:N/A:C).[c] VULNERABILITY DETAILS EXPLOITABILITY This vulnerability could be exploited remotely. EXISTENCE OF EXPLOIT No known public exploits specifically target this vulnerability. DIFFICULTY An attacker with a moderate skill would be able to exploit this vulnerability. MITIGATION IOServer released Beta driver beta2042.exe resolves this vulnerability. This version has already been superseded by beta2043.exe. Information about this version of this product is available on the IOServer Web site: http://www.ioserver.com/ The researchers suggest the following mitigation: Block DNP3 traffic from traversing onto business or corporate networks through the use of an IPS or firewall with DPN3-specific rule sets. ICS-CERT encourages asset owners to take additional defensive measures to protect against this and other cybersecurity risks. Minimize network exposure for all control system devices. Critical devices should not directly face the Internet. Locate control system networks and remote devices behind firewalls, and isolate them from the business network. When remote access is required, use secure methods, such as Virtual Private Networks (VPNs), recognizing that VPN is only as secure as the connected devices. ICS-CERT also provides a section for control systems security recommended practices on the ICS-CERT Web page. Several recommended practices are available for reading and download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies.[d] ICS-CERT reminds organizations to perform proper impact analysis and risk assessment prior to taking defensive measures. Additional mitigation guidance and recommended practices are publicly available in the ICS-CERT Technical Information Paper, ICS-TIP-12-146-01B-Targeted Cyber Intrusion Detection and Mitigation Strategies,[e] that is available for download from the ICS-CERT Web page (http://ics-cert.us-cert.gov/). Organizations observing any suspected malicious activity should follow their established internal procedures and report their findings to ICS-CERT for tracking and correlation against other incidents. a. CWE-20: Improper Input Validation http://cwe.mitre.org/data/definitions/20.html, Web site last accessed August 01, 2013. b. NVD, http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2013-2790 , NIST uses this advisory to create the CVE Web site report. This Web site will be active sometime after publication of this advisory. c. CVSS Calculator, http://nvd.nist.gov/cvss.cfm?version=2&vector=AV:N/AC:M/Au:N/C:N/I:N/A:C Web site last accessed August 01, 2013. d. CSSP Recommended Practices, http://ics-cert.us-cert.gov/content/recommended-practices, Web site last accessed August 01, 2013. e. Targeted Cyber Intrusion Detection and Mitigation Strategies, http://ics-cert.us-cert.gov/tips/ICS-TIP-12-146-01B, Web site last accessed August 01, 2013. Contact Information For any questions related to this report, please contact ICS-CERT at: Email: ics-cert@hq.dhs.gov Toll Free: 1-877-776-7585 International Callers: (208) 526-0900 For industrial control systems security information and incident reporting: http://ics-cert.us-cert.gov ICS-CERT continuously strives to improve its products and services. You can help by answering a short series of questions about this product at the following URL: https://forms.us-cert.gov/ncsd-feedback/. Legal For Legal Information pertaining to this document, please consult http://ics-cert.us-cert.gov/Legal-Disclaimer - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. NOTE: Third Party Rights This security bulletin is provided as a service to AusCERT's members. As AusCERT did not write the document quoted above, AusCERT has had no control over its content. The decision to follow or act on information or advice contained in this security bulletin is the responsibility of each user or organisation, and should be considered in accordance with your organisation's site policies and procedures. AusCERT takes no responsibility for consequences which may arise from following or acting on information or advice contained in this security bulletin. NOTE: This is only the original release of the security bulletin. It may not be updated when updates to the original are made. If downloading at a later date, it is recommended that the bulletin is retrieved directly from the author's website to ensure that the information is still current. Contact information for the authors of the original document is included in the Security Bulletin above. If you have any questions or need further information, please contact them directly. Previous advisories and external security bulletins can be retrieved from: http://www.auscert.org.au/render.html?cid=1980 =========================================================================== Australian Computer Emergency Response Team The University of Queensland Brisbane Qld 4072 Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). 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