Python Burp Extension code snippet to use the Cookie Jar for JWTs (medium post).

jwt_set.py

def performAction(self, current_request, macro_items):
	# grab some stuff from the current request
	req_text = self.helpers.bytesToString(current_request.getRequest())

	# grab jwt from cookie jar
	jwt = self.getCookieValue(self.cookieDomain, self.cookieName)

	# does a value exist yet?
	if jwt != None:
		# replace the old token with the stored value
		header_replace = "%s: %s" % (self.cookieName, jwt)
		req_text = re.sub(r"\r\n" + self.cookieName + ": .*\r\n", "\r\n" + header_replace + "\r\n" , req_text)

		# set the current request
		current_request.setRequest(self.helpers.stringToBytes(req_text))

There is an Error when add this extension to Burp, it seems like it missing Burp specific imports

A couple of years late but @mc4e, you essentially replace the performAction function with this snippet. It would be something like this:

# python imports
import re
import sys

# Burp specific imports
from burp import IBurpExtender
from burp import ISessionHandlingAction
from burp import ICookie

# For using the debugging tools from
# https://github.com/securityMB/burp-exceptions
try:
    from exceptions_fix import FixBurpExceptions
except ImportError:
    pass

class Cookie(ICookie):
	
	def getDomain(self):
		return self.cookie_domain

	def getPath(self):
		return self.cookie_path

	def getExpiration(self):
		return self.cookie_expiration

	def getName(self):
		return self.cookie_name

	def getValue(self):
		return self.cookie_value

	def __init__(self, cookie_domain=None, cookie_name=None, cookie_value=None, cookie_path=None, cookie_expiration=None):
		self.cookie_domain = cookie_domain
		self.cookie_name = cookie_name
		self.cookie_value = cookie_value
		self.cookie_path = cookie_path
		self.cookie_expiration = cookie_expiration

class BurpExtender(IBurpExtender, ISessionHandlingAction):

	#
	# Define config and gui variables
	#
	cookieName = 'jwt'
	cookieDomain = 'dummy.com'

	#
	# Define some cookie functions
	#
	def deleteCookie(self, domain, name):
		cookies = self.callbacks.getCookieJarContents()
		for cookie in cookies:
			#self.stdout.println("%s = %s" % (cookie.getName(), cookie.getValue()))	
			if cookie.getDomain() == domain and cookie.getName() == name:
				cookie_to_be_nuked = Cookie(cookie.getDomain(), cookie.getName(), None,  cookie.getPath(), cookie.getExpiration())
				self.callbacks.updateCookieJar(cookie_to_be_nuked)
				break

	def createCookie(self, domain, name, value, path=None, expiration=None):
		cookie_to_be_created = Cookie(domain, name, value,  path, expiration)
		self.callbacks.updateCookieJar(cookie_to_be_created)

	def setCookie(self, domain, name, value):
		cookies = self.callbacks.getCookieJarContents()
		for cookie in cookies:
			#self.stdout.println("%s = %s" % (cookie.getName(), cookie.getValue()))	
			if cookie.getDomain() == domain and cookie.getName() == name:
				cookie_to_be_set = Cookie(cookie.getDomain(), cookie.getName(), value,  cookie.getPath(), cookie.getExpiration())
				self.callbacks.updateCookieJar(cookie_to_be_set)
				break

	def getCookieValue(self, domain, name):
		cookies = self.callbacks.getCookieJarContents()
		for cookie in cookies:
			#self.stdout.println("%s = %s" % (cookie.getName(), cookie.getValue()))	
			if cookie.getDomain() == domain and cookie.getName() == name:
				return cookie.getValue()


	#
	# implement IBurpExtender
	#
	def	registerExtenderCallbacks(self, callbacks):
		# keep a reference to our callbacks object
		self.callbacks = callbacks

		# obtain an extension helpers object
		self.helpers = callbacks.getHelpers()

		# set our extension name
		callbacks.setExtensionName("JWT - Set")

		# register ourselves a Session Handling Action
		callbacks.registerSessionHandlingAction(self)

		# Used by the custom debugging tools
		sys.stdout = callbacks.getStdout()

		print("DEBUG: JWT Set - Enabled!")

		return

	#
	# Implement ISessionHandlingAction
	#
	def getActionName(self):
		return "JWT - Store & Set"

	def performAction(self, current_request, macro_items):
		# grab some stuff from the current request
		req_text = self.helpers.bytesToString(current_request.getRequest())

		# grab jwt from cookie jar
		jwt = self.getCookieValue(self.cookieDomain, self.cookieName)

		# does a value exist yet?
		if jwt != None:
			# replace the old token with the stored value
			header_replace = "%s: %s" % (self.cookieName, jwt)
			req_text = re.sub(r"\r\n" + self.cookieName + ": .*\r\n", "\r\n" + header_replace + "\r\n" , req_text)

			# set the current request
			current_request.setRequest(self.helpers.stringToBytes(req_text))
try:
    FixBurpExceptions()
except:
    pass