diff --git a/cve_2016-1494.diff b/cve_2016-1494.diff new file mode 100644 index 0000000..dce6a99 --- /dev/null +++ b/cve_2016-1494.diff @@ -0,0 +1,103 @@ +# HG changeset patch +# User Filippo Valsorda +# Date 1450226563 0 +# Node ID 0cbcc529926afd61c6df4f50cfc29971beafd2c2 +# Parent 2baab06c8b867b01ec82b02118d4872a931a0437 +Fix BB'06 attack in verify() by switching from parsing to comparison + +diff --git a/rsa/pkcs1.py b/rsa/pkcs1.py +--- a/rsa/pkcs1.py ++++ b/rsa/pkcs1.py +@@ -22,10 +22,10 @@ + At least 8 bytes of random padding is used when encrypting a message. This makes + these methods much more secure than the ones in the ``rsa`` module. + +-WARNING: this module leaks information when decryption or verification fails. +-The exceptions that are raised contain the Python traceback information, which +-can be used to deduce where in the process the failure occurred. DO NOT PASS +-SUCH INFORMATION to your users. ++WARNING: this module leaks information when decryption fails. The exceptions ++that are raised contain the Python traceback information, which can be used to ++deduce where in the process the failure occurred. DO NOT PASS SUCH INFORMATION ++to your users. + ''' + + import hashlib +@@ -288,37 +288,23 @@ + :param pub_key: the :py:class:`rsa.PublicKey` of the person signing the message. + :raise VerificationError: when the signature doesn't match the message. + +- .. warning:: +- +- Never display the stack trace of a +- :py:class:`rsa.pkcs1.VerificationError` exception. It shows where in +- the code the exception occurred, and thus leaks information about the +- key. It's only a tiny bit of information, but every bit makes cracking +- the keys easier. +- + ''' + +- blocksize = common.byte_size(pub_key.n) ++ keylength = common.byte_size(pub_key.n) + encrypted = transform.bytes2int(signature) + decrypted = core.decrypt_int(encrypted, pub_key.e, pub_key.n) +- clearsig = transform.int2bytes(decrypted, blocksize) +- +- # If we can't find the signature marker, verification failed. +- if clearsig[0:2] != b('\x00\x01'): +- raise VerificationError('Verification failed') ++ clearsig = transform.int2bytes(decrypted, keylength) + +- # Find the 00 separator between the padding and the payload +- try: +- sep_idx = clearsig.index(b('\x00'), 2) +- except ValueError: +- raise VerificationError('Verification failed') +- +- # Get the hash and the hash method +- (method_name, signature_hash) = _find_method_hash(clearsig[sep_idx+1:]) ++ # Get the hash method ++ method_name = _find_method_hash(clearsig) + message_hash = _hash(message, method_name) + +- # Compare the real hash to the hash in the signature +- if message_hash != signature_hash: ++ # Reconstruct the expected padded hash ++ cleartext = HASH_ASN1[method_name] + message_hash ++ expected = _pad_for_signing(cleartext, keylength) ++ ++ # Compare with the signed one ++ if expected != clearsig: + raise VerificationError('Verification failed') + + return True +@@ -351,24 +337,20 @@ + return hasher.digest() + + +-def _find_method_hash(method_hash): +- '''Finds the hash method and the hash itself. ++def _find_method_hash(clearsig): ++ '''Finds the hash method. + +- :param method_hash: ASN1 code for the hash method concatenated with the +- hash itself. ++ :param clearsig: full padded ASN1 and hash. + +- :return: tuple (method, hash) where ``method`` is the used hash method, and +- ``hash`` is the hash itself. ++ :return: the used hash method. + + :raise VerificationFailed: when the hash method cannot be found + + ''' + + for (hashname, asn1code) in HASH_ASN1.items(): +- if not method_hash.startswith(asn1code): +- continue +- +- return (hashname, method_hash[len(asn1code):]) ++ if asn1code in clearsig: ++ return hashname + + raise VerificationError('Verification failed') diff --git a/python-rsa.changes b/python-rsa.changes index 2c570d7..6ddca16 100644 --- a/python-rsa.changes +++ b/python-rsa.changes @@ -1,3 +1,9 @@ +------------------------------------------------------------------- +Tue Jan 5 18:39:56 UTC 2016 - rjschwei@suse.com + +- Fix CVE 2016-1494 (bsc#960680) + - Add patch cve_2016-1494.diff + ------------------------------------------------------------------- Tue Dec 1 15:02:09 UTC 2015 - rjschwei@suse.com diff --git a/python-rsa.spec b/python-rsa.spec index adbc0bc..bec9614 100644 --- a/python-rsa.spec +++ b/python-rsa.spec @@ -1,7 +1,7 @@ # # spec file for package python-rsa # -# Copyright (c) 2015 SUSE LINUX GmbH, Nuernberg, Germany. +# Copyright (c) 2016 SUSE LINUX GmbH, Nuernberg, Germany. # # All modifications and additions to the file contributed by third parties # remain the property of their copyright owners, unless otherwise agreed @@ -24,6 +24,7 @@ Summary: Pure-Python RSA Implementation License: Apache-2.0 Group: Development/Languages/Python Source: http://pypi.python.org/packages/source/r/rsa/rsa-%{version}.tar.gz +Patch0: cve_2016-1494.diff BuildRoot: %{_tmppath}/%{name}-%{version}-build BuildRequires: python-devel BuildRequires: python-pyasn1 @@ -55,6 +56,7 @@ sed -i "s/pyrsa-sign/pyrsa-sign-%{py_ver}/" setup.py sed -i "s/pyrsa-verify/pyrsa-verify-%{py_ver}/" setup.py sed -i "s/pyrsa-encrypt-bigfile =/pyrsa-encrypt-bigfile-%{py_ver} =/" setup.py sed -i "s/pyrsa-decrypt-bigfile =/pyrsa-decrypt-bigfile-%{py_ver} =/" setup.py +%patch0 -p1 %build python setup.py build