1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
|
import pytest
import jwt
from jwt.algorithms import get_default_algorithms
from jwt.exceptions import InvalidKeyError
from .utils import crypto_required
priv_key_bytes = b"""-----BEGIN PRIVATE KEY-----
MC4CAQAwBQYDK2VwBCIEIIbBhdo2ah7X32i50GOzrCr4acZTe6BezUdRIixjTAdL
-----END PRIVATE KEY-----"""
pub_key_bytes = (
b"ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIPL1I9oiq+B8crkmuV4YViiUnhdLjCp3hvy1bNGuGfNL"
)
ssh_priv_key_bytes = b"""-----BEGIN EC PRIVATE KEY-----
MHcCAQEEIOWc7RbaNswMtNtc+n6WZDlUblMr2FBPo79fcGXsJlGQoAoGCCqGSM49
AwEHoUQDQgAElcy2RSSSgn2RA/xCGko79N+7FwoLZr3Z0ij/ENjow2XpUDwwKEKk
Ak3TDXC9U8nipMlGcY7sDpXp2XyhHEM+Rw==
-----END EC PRIVATE KEY-----"""
ssh_key_bytes = b"""ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBJXMtkUkkoJ9kQP8QhpKO/TfuxcKC2a92dIo/xDY6MNl6VA8MChCpAJN0w1wvVPJ4qTJRnGO7A6V6dl8oRxDPkc="""
class TestAdvisory:
@crypto_required
def test_ghsa_ffqj_6fqr_9h24(self):
# Generate ed25519 private key
# private_key = ed25519.Ed25519PrivateKey.generate()
# Get private key bytes as they would be stored in a file
# priv_key_bytes = private_key.private_bytes(
# encoding=serialization.Encoding.PEM,
# format=serialization.PrivateFormat.PKCS8,
# encryption_algorithm=serialization.NoEncryption(),
# )
# Get public key bytes as they would be stored in a file
# pub_key_bytes = private_key.public_key().public_bytes(
# encoding=serialization.Encoding.OpenSSH,
# format=serialization.PublicFormat.OpenSSH,
# )
# Making a good jwt token that should work by signing it
# with the private key
# encoded_good = jwt.encode({"test": 1234}, priv_key_bytes, algorithm="EdDSA")
encoded_good = "eyJ0eXAiOiJKV1QiLCJhbGciOiJFZERTQSJ9.eyJ0ZXN0IjoxMjM0fQ.M5y1EEavZkHSlj9i8yi9nXKKyPBSAUhDRTOYZi3zZY11tZItDaR3qwAye8pc74_lZY3Ogt9KPNFbVOSGnUBHDg"
# Using HMAC with the public key to trick the receiver to think that the
# public key is a HMAC secret
encoded_bad = "eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJ0ZXN0IjoxMjM0fQ.6ulDpqSlbHmQ8bZXhZRLFko9SwcHrghCwh8d-exJEE4"
algorithm_names = list(get_default_algorithms())
# Both of the jwt tokens are validated as valid
jwt.decode(
encoded_good,
pub_key_bytes,
algorithms=algorithm_names,
)
with pytest.raises(InvalidKeyError):
jwt.decode(
encoded_bad,
pub_key_bytes,
algorithms=algorithm_names,
)
# Of course the receiver should specify ed25519 algorithm to be used if
# they specify ed25519 public key. However, if other algorithms are used,
# the POC does not work
# HMAC specifies illegal strings for the HMAC secret in jwt/algorithms.py
#
# invalid_str ings = [
# b"-----BEGIN PUBLIC KEY-----",
# b"-----BEGIN CERTIFICATE-----",
# b"-----BEGIN RSA PUBLIC KEY-----",
# b"ssh-rsa",
# ]
#
# However, OKPAlgorithm (ed25519) accepts the following in jwt/algorithms.py:
#
# if "-----BEGIN PUBLIC" in str_key:
# return load_pem_public_key(key)
# if "-----BEGIN PRIVATE" in str_key:
# return load_pem_private_key(key, password=None)
# if str_key[0:4] == "ssh-":
# return load_ssh_public_key(key)
#
# These should most likely made to match each other to prevent this behavior
# POC for the ecdsa-sha2-nistp256 format.
# openssl ecparam -genkey -name prime256v1 -noout -out ec256-key-priv.pem
# openssl ec -in ec256-key-priv.pem -pubout > ec256-key-pub.pem
# ssh-keygen -y -f ec256-key-priv.pem > ec256-key-ssh.pub
# Making a good jwt token that should work by signing it with the private key
# encoded_good = jwt.encode({"test": 1234}, ssh_priv_key_bytes, algorithm="ES256")
encoded_good = "eyJhbGciOiJFUzI1NiIsInR5cCI6IkpXVCJ9.eyJ0ZXN0IjoxMjM0fQ.NX42mS8cNqYoL3FOW9ZcKw8Nfq2mb6GqJVADeMA1-kyHAclilYo_edhdM_5eav9tBRQTlL0XMeu_WFE_mz3OXg"
# Using HMAC with the ssh public key to trick the receiver to think that the public key is a HMAC secret
# encoded_bad = jwt.encode({"test": 1234}, ssh_key_bytes, algorithm="HS256")
encoded_bad = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ0ZXN0IjoxMjM0fQ.5eYfbrbeGYmWfypQ6rMWXNZ8bdHcqKng5GPr9MJZITU"
algorithm_names = list(get_default_algorithms())
# Both of the jwt tokens are validated as valid
jwt.decode(
encoded_good,
ssh_key_bytes,
algorithms=algorithm_names,
)
with pytest.raises(InvalidKeyError):
jwt.decode(
encoded_bad,
ssh_key_bytes,
algorithms=algorithm_names,
)
|
