Siemens SINEMA Server Privilege Escalation Vulnerability (Update A)

OVERVIEW

This updated advisory is a follow-up to the original advisory titled ICSA-16-215-02 Siemens SINEMA Server Privilege Escalation Vulnerability that was published August 2, 2016, on the NCCIC/ICS-CERT web site.

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Security researcher rgod working with Trend Micro’s Zero Day Initiative has identified a privilege escalation vulnerability in the Siemens SINEMA Server. Siemens has produced a new version to mitigate this vulnerability.

AFFECTED PRODUCTS

Siemens reports that the vulnerability affects the following products:

• SINEMA Server: All versions prior to V13 SP2.

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IMPACT

Successful exploitation of this vulnerability could allow users, authenticated via the operating system, to escalate their privileges under certain conditions.

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

Siemens is a multinational company headquartered in Munich, Germany.

The affected product, SINEMA, is a network management appliance for industrial applications and allows network monitoring as well as diagnostics and reporting functions integrated into SCADA systems such as WinCC. According to Siemens, the SINEMA product is deployed across several sectors including Chemical, Commercial Facilities, Critical Manufacturing, Energy, Government Facilities, Water and Wastewater Systems, and others. Siemens estimates that this product is used worldwide.

VULNERABILITY CHARACTERIZATION

VULNERABILITY OVERVIEW

The file permissions set for the SINEMA Server application folder could allow users, authenticated via the operating system, to escalate their privileges.

CVE-2016-6486NVD, http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2016-6486, web site last accessed October 13, 2016. has been assigned to this vulnerability. A CVSS v3 base score of 7.3 has been calculated; the CVSS vector string is (AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H).CVSS Calculator, https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H, web site last accessed August 2, 2016.

VULNERABILITY DETAILS

EXPLOITABILITY

This vulnerability is not exploitable remotely and cannot be exploited without user interaction.

EXISTENCE OF EXPLOIT

No known public exploits specifically target this vulnerability. 

DIFFICULTY

An attacker with a low skill would be able to exploit this vulnerability.

MITIGATION

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Siemens has created a new version of SINEMA Server V13 SP2 which fixes the vulnerability and recommends users update to the new version. SINEMA Server V13 SP2 can be downloaded at the following location on the Siemens web site:

https://support.industry.siemens.com/cs/ww/en/view/109741833

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As a general security measure, Siemens strongly recommends protecting network access to SINEMA Server systems with appropriate mechanisms. It is advised to configure the environment according to Siemens operational guidelines in order to run the devices in a protected IT environment.

For more information on this vulnerability, please see Siemens Security Advisory SSA-321174 at the following location:

http://www.siemens.com/cert/advisories

ICS-CERT recommends that users take defensive measures to minimize the risk of exploitation of this vulnerability. Specifically, users should:

• Do not click web links or open unsolicited attachments in email messages.
• Refer to Recognizing and Avoiding Email ScamsRecognizing and Avoiding Email Scams, http://www.us-cert.gov/reading_room/emailscams_0905.pdf, web site last accessed August 2, 2016. for more information on avoiding email scams.
• Refer to Avoiding Social Engineering and Phishing AttacksNational Cyber Alert System Cyber Security Tip ST04-014, http://www.us-cert.gov/cas/tips/ST04-014.html, web site last accessed August 2, 2016. for more information on social engineering attacks.
• 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 reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures.

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.

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.

• Siemens