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This updated advisory is a follow-up to the original advisory titled ICSA-15-251-01 Advantech WebAccess Buffer Overflow Vulnerability that was published September 8, 2015, on the NCCIC/ICS-CERT web site.
Security researcher Praveen Darshanam reported a stack-based overflow vulnerability in Advantech’s WebAccess application.
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Advantech has produced a new version of WebAccess to mitigate this vulnerability.
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This vulnerability could be exploited remotely. Exploits that target this vulnerability are known to be publicly available.
The following WebAccess versions are affected:
- WebAccess, Version 8.0 and prior versions.
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Successful exploitation of this vulnerability may allow a remote attacker to crash the WebAccess application or to execute arbitrary code.
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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.
Advantech is based in Taiwan and has distribution offices in 21 countries worldwide.
The affected product, WebAccess, formerly known as BroadWin WebAccess, is a web-based SCADA and human-machine interface product. According to Advantech, WebAccess is deployed across several sectors including Commercial Facilities, Critical Manufacturing, Energy, and Government Facilities. Advantech estimates that these products are used globally.
STACK-BASED BUFFER OVERFLOWa
Multiple stack-based buffer overflow vulnerabilities have been identified in vulnerable DLLs that may allow a remote attacker to crash the application or allow arbitrary code execution.
This vulnerability could be exploited remotely.
EXISTENCE OF EXPLOIT
Exploits that target this vulnerability are publicly available.
An attacker with low skill would be able to exploit this vulnerability.
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Advantech has released a new version of WebAccess, Version 8.0_20150816, to mitigate the reported vulnerability. WebAccess, Version 8.0_20150816, is available at the following URL:
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ICS-CERT encourages asset owners to take defensive measures to protect against this and other cybersecurity risks.
- Isolate vulnerable systems from the Internet and untrusted systems; however, if connectivity is required, use a VPN solution and implement network monitoring.
- Using application whitelisting will not prevent memory-based attacks, such as exploiting buffer overflows vulnerabilities, but it can prevent shellcode from running executables that have not been authorized, thereby limiting the impact of memory-based attacks that call files.
- Minimize network exposure for all control system devices and/or systems, and ensure that they are not accessible from 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 VPNs may have vulnerabilities and should be updated to the most current version available. Also recognize 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 at: http://ics-cert.us-cert.gov/content/recommended-practices. Several recommended practices are available for reading and download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies. ICS-CERT reminds organizations to perform proper impact analysis and risk assessment prior to deploying 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, that is available for download from the ICS-CERT web site (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-121: Stack-based Buffer Overflow, http://cwe.mitre.org/data/definitions/121.html, web site last accessed September 8, 2015.
- b. NVD, http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2014-9208, web site last accessed September 15, 2015.
- c. CVSS Calculator, http://nvd.nist.gov/cvss.cfm?version=2&vector=AV:N/AC:L/Au:N/C:C/I:C/A:C, web site last accessed September 8, 2015.
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