NPLUG Wireless Repeater CSRF / XSS / Authentication Bypass

Credit: Patrick Costa
Risk: Medium
Local: No
Remote: Yes

=====[ Tempest Security Intelligence ]===================================== Multiple vulnerabilities in NPLUG wireless repeater CVE-2018-12455: Authentication bypass CVE-2018-12456: Multiple CSRF CVE-2018-17337: XSS via SSID ------------------------------------------------------- Author: - Patrick Costa < @patrickrbc > Tempest Security Intelligence - Recife, PE - Brazil =====[ Table of Contents ]================================================= 1. Overview 2. Detailed description 3. Affected versions & Solutions 4. Timeline of disclosure 5. Thanks & Acknowledgements 6. References =====[ Overview ]========================================================== * System affected : NPLUG wireless repeater [1] * Version : * Impact : An attacker can get root access on the device. =====[ Detailed description ]============================================== DISCLAIMER: This device uses a modified Tenda firmware [2]. Most of the vulnerabilities disclosed here were previously published regarding other similar device, besides that this device is pretty old. NPLUG wireless repeater has multiple vulnerabilities that can be combined to get a root access on the device. The first thing you can do to obtain access to the device is to exploit a XSS in the web interface (CVE-2018-17337). This can be exercised by placing an access point in an appropriate range from the device with a malicious SSID, e.g.: <script src="[pwned]"></script> If the user tries to scan for wireless networks using the web interface the XSS will pop and you're done. You can do all the stuff that will be described here. But, what if the user never uses this feature? Well, NPLUG's web interface has no CSRF (CVE-2018-12456) protection, so you can try to force a connected user to activate WAN access or change wireless security settings. Once you're inside NPLUG's network things became really easy. You can bypass the authentication just by setting a cookie named "admin:" (CVE-2018-12455). Example: curl -I HTTP/1.0 302 Redirect ... curl -I -H "Cookie: admin:=" HTTP/1.0 200 OK ... Now you have access to all the web interface features and you can download the config at containig passwords in plain text. If that is not enough for you, you can activate telnet daemon by making a simple GET request to /goform/telnetd and guess what! Root access with no password. Lately, I found out that this firmware had a binary that would work as the same backdoor previously reported for Tenda routers [3]. However, the service is not started by default and even when manually starting it, I couldn't exploit it for some reason. But there is not much need to do so. =====[ Affected versions & Solutions ]===================================== This test was performed against version but previous versions are probably vulnerable. =====[ Timeline of disclosure ]============================================ 15/06/2018 - Vendor contacted. 04/07/2018 - Vendor requested time to verify. 22/08/2018 - Vendor replied they won't patch it. =====[ Thanks & Acknowledgements ]========================================= - Felipe Xavier < filipe.xavier () > - Gustavo Pimentel < gustavo.pimentel ()> - Tempest Security Intelligence [4] =====[ References ]======================================================== [1] [2] [3] [4]

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