GHSA-7hpf-g48v-hw3j

Summary

A command injection vulnerability in the Web SSH feature allows an authenticated attacker to execute arbitrary commands as root on the host.

Details

Zoraxy has a Web SSH terminal feature that allows authenticated users to connect to SSH servers from their browsers. In HandleCreateProxySession the request to create an SSH session is handled. After checking for the presence of required parameters, ensuring that the target is not the loopback interface and that there is actually an SSH service running on the target, CreateNewConnection is called:

https://github.com/tobychui/zoraxy/blob/e79a70b7acfa45c2445aff9d60e4e7525c89fec8/src/mod/sshprox/sshprox.go#L165-L178

In line 178, the gotty binary is executed running sshCommand from the line above. It contains the user-controlled variable connAddr, which includes the hostname of the SSH server and - if provided - the username. An attacker can exploit the username variable to escape from the bash command and inject arbitrary commands into sshCommand. This is possible, because, unlike hostname and port, the username is not validated or sanitized.

This vulnerability was introduced in https://github.com/tobychui/zoraxy/commit/c07d5f85dfc37bd32819358ed7d4bc32c604e8f0. If Zoraxy is run without authentication of the management interface (started with-noauth), this vulnerability can be exploited without authentication. Additionally, if Zoraxy is run in Docker with the Docker socket mounted (as described in https://github.com/tobychui/zoraxy/blob/9cb315ea6739d1cc201b690322d25166b12dc5db/docker/README.md), this vulnerability can be exploited to escape the Zoraxy container and gain access to the Docker host.

PoC

1. Download and run Zoraxy as described in the README
2. Setup a user
3. Login as user
4. Navigate to Other -> Network Tools -> Connection
5. Enter hostname / IP of any server with SSH running, e.g. github.com
6. Enter ; bash ; as user
7. Click Connect using SSH
8. A window will open with bash running on the Zoraxy host

Demo:

https://github.com/user-attachments/assets/5a3d8771-167f-4a79-8665-ed0dfb490181

Impact

This vulnerability allows an authenticated attacker to gain remote code execution with the privileges of the Zoraxy process (root by default). This affects Zoraxy versions 2.6.1 through 3.1.2.