Sauter NovaWeb Web HMI Authentication Bypass Vulnerability

OVERVIEW

Independent researcher Maxim Rupp has identified an authentication bypass vulnerability in Sauter’s NovaWeb web HMI application. Sauter has not produced a mitigation for this vulnerability. This product was discontinued in 2013 and is no longer supported.

This vulnerability could be exploited remotely.

AFFECTED PRODUCTS

The following NovaWeb versions are affected:

• NovaWeb web HMI, all versions.

IMPACT

An attacker can bypass authentication by modifying values in a cookie.

Impact to individual organizations depends on many factors that are unique to each organization. NCCIC/ICS-CERT recommends that organizations evaluate the impact of this vulnerability based on their operational environment, architecture, and product implementation.

BACKGROUND

Sauter is a Germany-based company that also maintains an office in Switzerland.

The affected product, novaWeb web HMI, is a web-based HMI system. According to Sauter, novaWeb was deployed in the Commercial Facilities and Critical Manufacturing sectors. Sauter estimates that this product is used primarily in Europe.

VULNERABILITY CHARACTERIZATION

VULNERABILITY OVERVIEW

The application uses a protection mechanism that relies on the existence or values of a cookie, but it does not properly ensure that the cookie is valid for the associated user.

CVE-2016-5782NVD, https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2016-5782, NIST uses this advisory to create the CVE web site report. This web site will be active sometime after publication of this advisory. has been assigned to this vulnerability. A CVSS v3 base score of  7.2 has been assigned; the CVSS vector string is (AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H).CVSS Calculator, https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H, web site last accessed December 08, 2016.

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 low skill would be able to exploit this vulnerability.

MITIGATION

Sauter has not produced a mitigation for this vulnerability. This product was discontinued in 2013 and is no longer supported.

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

• 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. 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.

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.

• Sauter