Re: RFR: 8255739: x509Certificate returns � for invalid subjectAlternativeNames [v2]
Michael StJohns
mstjohns at comcast.net
Sat Jan 22 22:46:18 UTC 2022
Hi Sean -
Inline.
On 1/21/2022 11:33 AM, Sean Mullan wrote:
> On Fri, 14 Jan 2022 11:18:23 GMT, Masanori Yano<myano at openjdk.org> wrote:
>
>>> Could you please review the JDK-8255739 bug fix?
>>>
>>> I think sun.security.x509.SubjectAlternativeNameExtension() should throw an exception for incorrect SubjectAlternativeNames instead of returning the substituted characters, which is explained in the description of BugDB.
>>>
>>> I modified DerValue.readStringInternal() not to read incorrect SubjectAlternativeNames and throw an IOException. sun.security.x509.X509CertInfo.parse() catch the IOExcepton and ignore it if SAN is a non-ciritical extension like the behavior of the IOException in readStringInternal(). So I added a test with -Djava.security.debug=x509 to confirm that.
>> Masanori Yano has updated the pull request incrementally with one additional commit since the last revision:
>>
>> 8255739: x509Certificate returns � for invalid subjectAlternativeNames
>> _Mailing list message from [Michael StJohns](mailto:mstjohns at comcast.net) on [security-dev](mailto:security-dev at mail.openjdk.java.net):_
>>
>> On 1/18/2022 4:10 PM, Sean Mullan wrote:
>>
>> Hi -
>>
>> Bouncycastle started enforcing properly encoded? INTEGERs a while back and that caused one of my programs to start failing due to a TPM X509 endorsement certificate just having the TPM serial number stuffed into the certificate serial number without normalizing it to the appropriate INTEGER encoding.? BC provided a work around (setting "org.bouncycastle.asn1.allow_unsafe_integer") which gave me time to re-code around the problem.? If you're going to break things, it may be useful to provide a work around similar to what they did.
> Do you know the behavior of the JDK X.509 CertificateFactory implementation? Did it accept or reject this serial number?
It accepted the serial number:
> [
> [
> Version: V3
> Subject:
> Signature Algorithm: SHA256withECDSA, OID = 1.2.840.10045.4.3.2
>
> Key: Sun RSA public key, 2048 bits
> modulus:
> 244030580540745092613654475993648434932553330564847517407727188658248
> 32223177660143311229959664585582409529625785574450992069681603560492386013716136
> 32364832338166792867574600908839414339721021812629840173006767022634407898831293
> 85934831807840338360685996173024268943864659869938519459993447390570376982441341
> 45952422087437605410761245329340711833296479315725697546185458730724484238852701
> 80315770789789435860018869046480700786553465339467127182438028195537091676054789
> 84722755281453369500125757853796162260084162669462853871135753998130894343437638
> 04195331153338279046418652746376364246586098919744901616926689536893
> public exponent: 65537
> Validity: [From: Sun Nov 26 20:52:10 EST 2017,
> To: Thu Dec 30 19:00:00 EST 2049]
> Issuer: CN=www.intel.com, OU=TPM EK intermediate for
> SPTH_EPID_PROD_RK_0, O=In
> tel Corporation, L=Santa Clara, ST=CA, C=US
> _*SerialNumber: [ 048fe61d 2882d3cd 488ab130 b94fbc89 284b32]*_
>
> Certificate Extensions: 9
> [1]: ObjectId: 2.5.29.9 Criticality=false
> Extension unknown: DER encoded OCTET string =
> 0000: 04 1A 30 18 30 16 06 05 67 81 05 02 10 31 0D 30 ..0.0...g....1.0
> 0010: 0B 0C 03 32 2E 30 02 01 00 02 01 5D ...2.0.....]
>
>
> [2]: ObjectId: 1.3.6.1.5.5.7.1.1 Criticality=false
> AuthorityInfoAccess [
> [
> accessMethod: caIssuers
> accessLocation: URIName:
> http://upgrades.intel.com/content/CRL/ekcert/SPTH_EP
> ID_PROD_RK_0.cer
> ]
> ]
>
> [3]: ObjectId: 2.5.29.35 Criticality=false
> AuthorityKeyIdentifier [
> KeyIdentifier [
> 0000: 6C A9 DF 62 A1 AA E2 3E 0F EB 7C 3F 5E B8 E6 1E l..b...>...?^...
> 0010: CA C1 7C B7 ....
> ]
> ]
>
> [4]: ObjectId: 2.5.29.19 Criticality=true
> BasicConstraints:[
> CA:false
> PathLen: undefined
> ]
>
> [5]: ObjectId: 2.5.29.31 Criticality=false
> CRLDistributionPoints [
> [DistributionPoint:
> [URIName:
> http://upgrades.intel.com/content/CRL/ekcert/SPTH_EPID_PROD_RK_0.
> crl]
> ]]
>
> [6]: ObjectId: 2.5.29.32 Criticality=false
> CertificatePolicies [
> [CertificatePolicyId: [1.2.840.113741.1.5.2.1]
> [PolicyQualifierInfo: [
> qualifierID: 1.3.6.1.5.5.7.2.1
> qualifier: 0000: 16 46 68 74 74 70 3A 2F 2F 75 70 67 72 61 64 65
> .Fhttp://u
> pgrade
> 0010: 73 2E 69 6E 74 65 6C 2E 63 6F 6D 2F 63 6F 6E 74 s.intel.com/cont
> 0020: 65 6E 74 2F 43 52 4C 2F 65 6B 63 65 72 74 2F 45 ent/CRL/ekcert/E
> 0030: 4B 63 65 72 74 50 6F 6C 69 63 79 53 74 61 74 65 KcertPolicyState
> 0040: 6D 65 6E 74 2E 70 64 66 ment.pdf
>
> ], PolicyQualifierInfo: [
> qualifierID: 1.3.6.1.5.5.7.2.2
> qualifier: 0000: 30 2A 0C 28 54 43 50 41 20 54 72 75 73 74 65 64
> 0*.(TCPA T
> rusted
> 0010: 20 50 6C 61 74 66 6F 72 6D 20 4D 6F 64 75 6C 65 Platform Module
> 0020: 20 45 6E 64 6F 72 73 65 6D 65 6E 74 Endorsement
>
> ]] ]
> ]
>
> [7]: ObjectId: 2.5.29.37 Criticality=false
> ExtendedKeyUsages [
> 2.23.133.8.1
> ]
>
> [8]: ObjectId: 2.5.29.15 Criticality=true
> KeyUsage [
> Key_Encipherment
> ]
>
> [9]: ObjectId: 2.5.29.17 Criticality=true
> SubjectAlternativeName [
> OID.2.23.133.2.3=id:00020000, OID.2.23.133.2.2=SPT,
> OID.2.23.133.2.1=id:494E54
> 43
> ]
>
> ]
> Algorithm: [SHA256withECDSA]
> Signature:
> 0000: 30 45 02 20 6C 91 72 DF DC 9E 59 AB 57 81 E2 FC 0E. l.r...Y.W...
> 0010: 00 EA 0A 0D A7 4D 94 0F 0E FA BA E1 30 08 19 E5 .....M......0...
> 0020: CF 25 33 27 02 21 00 E6 F0 C0 75 EF 8E C6 C3 84 .%3'.!....u.....
> 0030: 54 9F 7A DD D5 A6 5F E0 7C 42 D7 5A B0 8A 1A 1C T.z..._..B.Z....
> 0040: B3 6E D6 56 8F A2 44 .n.V..D
>
> ]
Here's the ASN1 for the serial number:
> 02 14
> 00 04 8f e6 1d 28 82 d3 cd 48 8a b1 30 b9 4f bc 89 28 4b 32
In this case, the encoding should not have included the leading '00'
byte. That 20 byte value is what I get if I query the TPM directly for
its serial number.
Here's what org.bouncycastle.asn1.ASN1Integer does:
> switch (bytes.length)
> {
> case 0:
> return true;
> case 1:
> return false;
> default:
> return bytes[0] == (bytes[1] >> 7)
> // Apply loose validation, see note in public
> constructor ASN1Integer(byte[])
> &&
> !Properties.isOverrideSet("org.bouncycastle.asn1.allow_unsafe_integer");
> }
Basically returns "true" to the question "isMalformatted" if there is a
leading zero byte and the high bit of the second byte isn't set or if
the first is 0xff and the high bit of the second byte is set.
E.g. according to 8.3.2 of X.690:
> If the contents octets of an integer value encoding consist of more
> than one octet, then the bits of the first octet
> and bit 8 of the second octet
> a)shall not all be ones; and
> b)shall not all be zero.
> NOTE – These rules ensure that an integer value is always encoded in
> the smallest possible number of octets
So the JDK implementation violates the standard.
>
>> In any event, DerValue.java uses "new String(byteArrayValue, charsetType)" to produce the various String values including in getIA5String().? I.e.,
>>
>>> public?String(byte[]?bytes,
>>> Charset ?charset)
>>> Constructs a new |String| by decoding the specified array of bytes
>>> using the specified charset. The length of the new |String| is a
>>> function of the charset, and hence may not be equal to the length of
>>> the byte array.
>>> _*This method always replaces malformed-input and unmappable-character
>>> sequences with this charset's default replacement string.*_ The
>>> |CharsetDecoder| class should be used when more control over the
>>> decoding process is required.
>> Perhaps it might make sense to update the various places where this is used in DerValue to CharsetDecoder and to use charsetDecoder.onMalformedInput() and charsetDecoder.onUnmappableCharacter() to set the appropriate action related to parsing the byte array into a String of a given charset?? That action could be set based on the presence of the bypass property.
> I believe that was originally suggested by the submitter as a potential solution. But it doesn't seem like it is that useful or there would be much demand for this.
I wish CertificateFactorylgetInstance() could accept a parameter object
describing how strict or loose an encoding would be accepted by the
parsing engine.
On the more general note of whether there's demand - it would be useful
if there were a way to avoid accepting certificates that are
malformatted. I originally started using the BC certificate factory
because the SUN factory didn't understand RSA-OAEP as a key type in
SubjectKeyInfo and I was getting a few of those from a group of TPMs.
But I do understand the limitations of resources.
>
>> I don't think the change as proposed is backward-compatible safe enough, nor does it really address the general issue of poorly encoded DER String values in a certificate.
> Yes, I have come to the conclusion that this is probably too risky to fix. An application that is depending on a DNSName should be doing additional matching checks to verify that the structure of the name is correct, and it doesn't violate other types of rules, such as wildcards involving public suffixes, etc. (The JDK code does these additional checks when verifying TLS server certificates).
Yes.
Thanks - Mike
>
> See alsohttps://groups.google.com/g/mozilla.dev.security.policy/c/Av6oZxbjvB4/m/NW6lGkgYBwAJ and the linked report of various anomalies in commonNames and Subject Alternative Names in server auth certificates issued by public CAs.
>
> -------------
>
> PR:https://git.openjdk.java.net/jdk/pull/6928
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