Issue #18709: Fix CVE-2013-4238. The SSL module now handles NULL bytes

inside subjectAltName correctly. Formerly the module has used OpenSSL's
GENERAL_NAME_print() function to get the string represention of ASN.1
strings for rfc822Name (email), dNSName (DNS) and
uniformResourceIdentifier (URI).
This commit is contained in:
Christian Heimes 2013-08-17 00:54:47 +02:00
parent 29c3fc5d8f
commit 824f7f366d
4 changed files with 184 additions and 5 deletions

View file

@ -55,6 +55,7 @@ BADCERT = data_file("badcert.pem")
WRONGCERT = data_file("XXXnonexisting.pem")
BADKEY = data_file("badkey.pem")
NOKIACERT = data_file("nokia.pem")
NULLBYTECERT = data_file("nullbytecert.pem")
DHFILE = data_file("dh512.pem")
BYTES_DHFILE = os.fsencode(DHFILE)
@ -162,6 +163,27 @@ class BasicSocketTests(unittest.TestCase):
('DNS', 'projects.forum.nokia.com'))
)
def test_parse_cert_CVE_2013_4238(self):
p = ssl._ssl._test_decode_cert(NULLBYTECERT)
if support.verbose:
sys.stdout.write("\n" + pprint.pformat(p) + "\n")
subject = ((('countryName', 'US'),),
(('stateOrProvinceName', 'Oregon'),),
(('localityName', 'Beaverton'),),
(('organizationName', 'Python Software Foundation'),),
(('organizationalUnitName', 'Python Core Development'),),
(('commonName', 'null.python.org\x00example.org'),),
(('emailAddress', 'python-dev@python.org'),))
self.assertEqual(p['subject'], subject)
self.assertEqual(p['issuer'], subject)
self.assertEqual(p['subjectAltName'],
(('DNS', 'altnull.python.org\x00example.com'),
('email', 'null@python.org\x00user@example.org'),
('URI', 'http://null.python.org\x00http://example.org'),
('IP Address', '192.0.2.1'),
('IP Address', '2001:DB8:0:0:0:0:0:1\n'))
)
def test_DER_to_PEM(self):
with open(SVN_PYTHON_ORG_ROOT_CERT, 'r') as f:
pem = f.read()
@ -294,6 +316,13 @@ class BasicSocketTests(unittest.TestCase):
fail(cert, 'foo.a.com')
fail(cert, 'bar.foo.com')
# NULL bytes are bad, CVE-2013-4073
cert = {'subject': ((('commonName',
'null.python.org\x00example.org'),),)}
ok(cert, 'null.python.org\x00example.org') # or raise an error?
fail(cert, 'example.org')
fail(cert, 'null.python.org')
# Slightly fake real-world example
cert = {'notAfter': 'Jun 26 21:41:46 2011 GMT',
'subject': ((('commonName', 'linuxfrz.org'),),),