KL-001-2020-006 : Barco wePresent Authentication Bypass Title: Barco wePresent Authentication Bypass Advisory ID: KL-001-2020-006 Publication Date: 2020.11.20 Publication URL: https://korelogic.com/Resources/Advisories/KL-001-2020-006.txt 1. Vulnerability Details Affected Vendor: Barco Affected Product: wePresent WiPG-1600W Affected Version: 2.5.1.8 Platform: Embedded Linux CWE Classification: CWE-288: Authentication Bypass Using an Alternate Path or Channel CVE ID: CVE-2020-28333 2. Vulnerability Description The Barco wePresent web interface does not use session cookies for tracking authenticated sessions. Instead, the web interface uses a "SEID" token that is appended to the end of URLs in GET requests. Thus the "SEID" would be exposed in web proxy logs and browser history. An attacker that is able to capture the "SEID" and originate requests from the same IP address (via a NAT device or web proxy) would be able to access the user interface of the device without having to know the credentials. 3. Technical Description In order to make configuration changes to the Barco wePresent WiPG-1600W, a "random" value sent to the web interface client from the device is required to be provided -- the "SEID". It seems to be acting like a Session ID in a cookie. However, the "SEID" is passed as a parameter in URLs and in the body of POSTs. Since it is passed as a parameter in the URL, it can be logged by web proxies or browser history. An example is: https://192.168.2.200/cgi-bin/web_index.cgi?lang=en&src=AwSystem.html&ertqVvnKV4TjU9Vt Where "ertqVvnKV4TjU9Vt" is the SEID. No session cookie exists, just this value passed on the URL as a parameter, and in the body of POSTs to make configuration changes. This SEID is all that is required to access pages behind authentication or to make configuration changes via POSTs. There is no Authorization header passed in the HTTP requests. 4. Mitigation and Remediation Recommendation The vendor has released an updated firmware (2.5.3.12) which remediates the described vulnerability. Firmware and release notes are available at: https://www.barco.com/en/support/software/R33050104 5. Credit This vulnerability was discovered by Jim Becher (@jimbecher) of KoreLogic, Inc. 6. Disclosure Timeline 2020.08.24 - KoreLogic submits vulnerability details to Barco. 2020.08.25 - Barco acknowledges receipt and the intention to investigate. 2020.09.21 - Barco notifies KoreLogic that this issue, along with several others reported by KoreLogic, will require more than the standard 45 business day remediation timeline. Barco requests to delay coordinated disclosure until 2020.12.11. 2020.09.23 - KoreLogic agrees to 2020.12.11 coordinated disclosure. 2020.09.25 - Barco informs KoreLogic of their intent to acquire CVE number for this vulnerability. 2020.11.09 - Barco shares CVE number with KoreLogic and announces their intention to release the updated firmware ahead of schedule, on 2020.11.11. Request that KoreLogic delay public disclosure until 2020.11.20. 2020.11.11 - Barco firmware release. 2020.11.20 - KoreLogic public disclosure. 7. Proof of Concept See section (3) Technical Description. The contents of this advisory are copyright(c) 2020 KoreLogic, Inc. and are licensed under a Creative Commons Attribution Share-Alike 4.0 (United States) License: http://creativecommons.org/licenses/by-sa/4.0/ KoreLogic, Inc. is a founder-owned and operated company with a proven track record of providing security services to entities ranging from Fortune 500 to small and mid-sized companies. We are a highly skilled team of senior security consultants doing by-hand security assessments for the most important networks in the U.S. and around the world. We are also developers of various tools and resources aimed at helping the security community. https://www.korelogic.com/about-korelogic.html Our public vulnerability disclosure policy is available at: https://korelogic.com/KoreLogic-Public-Vulnerability-Disclosure-Policy.v2.3.txt