openssl-vulnkey produces 'false negative' when testing with a weak key

[wuergler]

Binary package hint: openssl-blacklist

************
Update (2008-08-09)
I found it worrying that openssl-vulnkey would not recognize the weak certificate and I have started clarifications which went in different directions. I have a strong speculation which I have not been able to test yet. I use a network which is serviced by a external service provider. HTTPS access to the internet goes through a proxy which seems to terminate outbound traffic. It then creates a separate HTTPS session to the actual server. Put another way: the certificate that I have downloaded in order to perform my test seems to be the one that has been created by the proxy on-the-fly. The subject name seems to be ok but the certificate does not seem to be the original one.
Put another way: openssl-vulnkey appears to be working fine.

Signed:
Urs Wuergler
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Dear all,

I installed Ubuntu 8.04 yesterday (2008-07-07), applied all relevant updates and installed 'openssl-blacklist' (using 'Update Manager' for all update-related tasks). I then used openssl-vulnkey to give a somewhat prominent, weak certificate a try [1].
To my surprise I received the message: "not blacklisted".

I have used other services such as the reputed
http://www.heise-online.co.uk/networks/tools/chksslkey
which confirm that the key material is indeed weak.

The OpenSSL version is '0.9.8g 19 OCT 2007' and I also installed 'openssl-blacklist-extra' even though this should not apply to the 1024 bit key in question.

The relevant certificate [1] in base64 encoding:

-----BEGIN CERTIFICATE-----
MIIFETCCBHqgAwIBAgIELKkQFTANBgkqhkiG9w0BAQQFADCBxDELMAkGA1UEBhMC
Q0gxCzAJBgNVBAgTAkJFMQ0wCwYDVQQHEwRCZXJuMSAwHgYDVQQKExdTd2lzc2Nv
bSBJVCBTZXJ2aWNlcyBBRzEaMBgGA1UECxMRSW50ZXJuZXQgU2VydmljZXMxKTAn
BgNVBAMTIFN3aXNzY29tIElUIFNlcnZpY2VzIFNDSVAgU3ViIENBMTAwLgYJKoZI
hvcNAQkBFiFlbmdpbmVlcmluZy5pbnRlcm5ldEBzd2lzc2NvbS5jb20wHhcNMDgw
NzA2MTMyNTA2WhcNMDkwNzA3MTMyNTA2WjCBujELMAkGA1UEBhMCQ0gxCzAJBgNV
BAgTAkJFMQ0wCwYDVQQHEwRCZXJuMSAwHgYDVQQKExdTd2lzc2NvbSBJVCBTZXJ2
aWNlcyBBRzEaMBgGA1UECxMRSW50ZXJuZXQgU2VydmljZXMxHzAdBgNVBAMTFmJh
ZC5jb2RlZnJvbXRoZTcwcy5vcmcxMDAuBgkqhkiG9w0BCQEWIWVuZ2luZWVyaW5n
LmludGVybmV0QHN3aXNzY29tLmNvbTCBnzANBgkqhkiG9w0BAQEFAAOBjQAwgYkC
gYEA1hnPBCSe45nOjyOkc7FxuvzONI35Wgxu41UTZETWB++7Oag+aqLvkfNU2xU5
9eae5HrU+XONZ/zQOHFR/XJ8YL9xGnz09oIL58lQWsPzQ5VK6vloKjOZmKhaiKqK
0heB9sg2jVBtOuO+oOW2NehaQHvkAqdAmYeki0SCWL0scE0CAwEAAaOCAhYwggIS
MAwGA1UdEwQFMAMBAf8wggIABglghkgBhvhCAQ0EggHxFoIB7VRoZSByZWFsIGNl
cnRpZmljYXRlIGRldGFpbHMgYXJlOgoKb3JpZ2luYWwgY2VydCBpc3N1ZXI6Ci9D
PVVTL1NUPUFyaXpvbmEvTD1TY290dHNkYWxlL089R29EYWRkeS5jb20sIEluYy4v
T1U9aHR0cDovL2NlcnRpZmljYXRlcy5nb2RhZGR5LmNvbS9yZXBvc2l0b3J5L0NO
PUdvIERhZGR5IFNlY3VyZSBDZXJ0aWZpY2F0aW9uIEF1dGhvcml0eS9zZXJpYWxO
dW1iZXI9MDc5NjkyODcKCm9yaWdpbmFsIGNlcnQgc3ViamVjdDoKL089YmFkLmNv
ZGVmcm9tdGhlNzBzLm9yZy9PVT1Eb21haW4gQ29udHJvbCBWYWxpZGF0ZWQvQ049
YmFkLmNvZGVmcm9tdGhlNzBzLm9yZwoKc2VyaWFsIG51bWJlcjoKNDRGRkE5CgpT
SEExIGZpbmdlcnByaW50Ogo6MDY6ZTE6NDE6Njk6NTI6YTc6NDk6MzQ6OWQ6ZjI6
OTI6YTU6ZGE6YWQ6NTc6NTY6MTE6OTc6MjY6MTgKCk1ENSBmaW5nZXJwcmludDoK
OmMyOjYyOmNlOjQ3OmI4OjFhOjc3OmQzOmZiOjk5Ojk5OjY2OjlmOjI0OmJmOjZl
CgowDQYJKoZIhvcNAQEEBQADgYEAzQaJTo6QTJ03T/3h8+2pkUAjHQEuofBNJjtS
WVDQsBBVa8gl2LZDyQNBvbM975B5ataounUyedj3vzHQIteaVjkgckuWWGXLX6II
KhotOCudka+ejkNydLxqdlQfNIQw56Lj5SA5b5eVQblyjYswEP4NzgafxD+matD0
cZtD8Gg=
-----END CERTIFICATE-----

I am not aware of another (potentially more comprehensive) blacklist and assume that openssl-vulnkey should be ready to use.

Any feedback on this would be highly appreciated as I need to verify hundreds of certificates.

Kind regards,

Urs Wuergler

[1] The weak test certificate at https://bad.codefromthe70s.org

[Jamie Strandboge (jdstrand)]

Thanks for your bug report and sorry for the delay in responding. Ubuntu (and Debian) have the most complete blacklists available in the openssl-blacklist and openssl-blacklist-extra packages (unless someone has released 8192 bit somewhere).

I ran openssl-vulnkey on the attached certificate, and it is not in the database. However, I did get the ssl cert from https://bad.codefromthe70s.org using:
$ openssl s_client -connect bad.codefromthe70s.org:443

then copied the certificate into a file. Running openssl-vulnkey on this file shows the certificate as compromised, and indeed, the cert from the website and the one supplied in this bug are different. I am therefore marking this bug as invalid. Please feel free to reopen if you have more information.