Merge pull request #51 from blacklanternsecurity/xmldsig_alg

xmldsig handling, fixed bug w/RSA alg
blacklanternsecurity · Apr 4, 2023 · 5b5e439 · 5b5e439
2 parents f5af593 + 98f1ec6
commit 5b5e439
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Showing 2 changed files with 43 additions and 2 deletions.
diff --git a/badsecrets/modules/generic_jwt.py b/badsecrets/modules/generic_jwt.py
@@ -1,12 +1,42 @@
 import re
 import jwt as j
+import json
+import base64
 from badsecrets.base import BadsecretsBase
 
+# XMLDSIG Translation Table
+
+XMLDSIG_table = {
+    "http://www.w3.org/2001/04/xmldsig-more#hmac-sha256": "HS256",
+    "http://www.w3.org/2001/04/xmldsig-more#hmac-sha384": "HS384",
+    "http://www.w3.org/2001/04/xmldsig-more#hmac-sha512": "HS512",
+    "http://www.w3.org/2001/04/xmldsig-more#rsa-sha256": "RS256",
+    "http://www.w3.org/2001/04/xmldsig-more#rsa-sha384": "RS384",
+    "http://www.w3.org/2001/04/xmldsig-more#rsa-sha512": "RS512",
+    "http://www.w3.org/2001/04/xmldsig-more#ecdsa-sha256": "ES256",
+    "http://www.w3.org/2001/04/xmldsig-more#ecdsa-sha384": "ES384",
+    "http://www.w3.org/2001/04/xmldsig-more#ecdsa-sha512": "ES512",
+    "http://www.w3.org/2007/05/xmldsig-more#sha256-rsa-MGF1": "PS256",
+    "http://www.w3.org/2007/05/xmldsig-more#sha384-rsa-MGF1": "PS384",
+    "http://www.w3.org/2007/05/xmldsig-more#sha512-rsa-MGF1": "PS512",
+}
+
 
 class Generic_JWT(BadsecretsBase):
     identify_regex = re.compile(r"eyJ(?:[\w-]*\.)(?:[\w-]*\.)[\w-]*")
     description = {"Product": "JSON Web Token (JWT)", "Secret": "HMAC/RSA Key"}
 
+    @staticmethod
+    def swap_algorithm(jwt, algorithm):
+        header = j.get_unverified_header(jwt)
+        header["alg"] = algorithm
+        header_encoded = (
+            base64.urlsafe_b64encode(json.dumps(header, separators=(",", ":")).encode()).rstrip(b"=").decode()
+        )
+        _, payload, signature = jwt.split(".")
+        new_jwt = f"{header_encoded}.{payload}.{signature}"
+        return new_jwt
+
     def carve_regex(self):
         return re.compile(r"(eyJ(?:[\w-]*\.)(?:[\w-]*\.)[\w-]*)")
 
@@ -35,6 +65,10 @@ def check_secret(self, JWT):
         except KeyError:
             return None
 
+        if algorithm in XMLDSIG_table.keys():
+            algorithm = XMLDSIG_table[algorithm]
+            JWT = self.swap_algorithm(JWT, algorithm)
+
         if algorithm[0].lower() == "h":
             for l in self.load_resource("jwt_secrets.txt"):
                 key = l.strip()
@@ -48,8 +82,7 @@ def check_secret(self, JWT):
         elif algorithm[0].lower() == "r":
             for l in self.load_resource("jwt_rsakeys_public.txt"):
                 private_key_name = l.split(":")[0]
-                public_key = l.split(":")[1]
-                public_key = b"-----BEGIN PUBLIC KEY-----\nMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA6cs10W3XKnr1MDoO0Ngf\nYEixdQy5e3m/E4POPC5t6yyc/eZZayytrA6CfaZXBKnYU4YKD06sJULj30qw/TJJ\nwphhb2a5s3sjXejL4KW2WTdP6F+DbSaokzvKVdaZ97GnLtiei8n6gnSE1xSsJ15+\nd9JHImekuW/ggksVbI26UTiXvfv7LUJ8ntt6wG1UQHWOvYbG81TTpZjItvZsYu1t\npekjNpOwCsIbO//S1JOiSgpuKp7HwCnQwABNEWyMuIAMlymMyocbTdQHcClogZC9\nbwokxTPZGmD9xZ+meaeVD5HONqASIJ1tOoFGsnwwwlEhwsul0FRs7qehuhJmKE5Z\nbwIDAQAB\n-----END PUBLIC KEY-----"
+                public_key = f"{l.split(':')[1]}".rstrip().encode().replace(b"\\n", b"\n")
                 r = self.jwtVerify(JWT, public_key, algorithm)
                 r["jwt_headers"] = jwt_headers
                 if r:

diff --git a/tests/generic_jwt_test.py b/tests/generic_jwt_test.py
@@ -27,3 +27,11 @@ def test_generic_jwt_negative():
         "eyJhbGciOiJIGzI4NiJ9.eyJJc3N1ZXIiOiJJc3N1ZXIiLCJVcEVEbEFtESI6IkJhZFNlE3JldHMiLCJlEHAiOjE1OTMxMzE0ODMsImlhdEI6MTQ2NjkwMzA4M30.ovqRikAo_0kKJ0GVrAwQlezymxrLGjcEiW_s3UJMMCo"
     )
     assert not found_key
+
+
+def test_generic_jwt_xmldsig():
+    x = Generic_JWT()
+    found_key = x.check_secret(
+        "eyJhbGciOiJodHRwOi8vd3d3LnczLm9yZy8yMDAxLzA0L3htbGRzaWctbW9yZSNobWFjLXNoYTI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c"
+    )
+    assert found_key