[INFRA-368] Insecure private key and hashing algorithm for update-center.json signing

[jenkins-infra-bot]

Hi Guys,

I am not jenkins/plugin developer, but I did notice this and I think you should consider it:

The update center certificate is using algorithms and key-sizes that are nowdays generally considered as insecure.

RSA length is: 512
Signature algorithm: RSAwithMD5

Root certificate could use SHA256 instead:
RSA length is: 2048
Signature algorithm: RSAwithSHA1

Combined with the insecure distribution channel (http) this can lead to very severe security breaches on user sites: Is there any better place to insert implant other than build server?

For convenience:

Certificate:
    Data:
Version: 1 (0x0)
Serial Number: 3735928565 (0xdeadbef5)
    Signature Algorithm: md5WithRSAEncryption
Issuer: C=US, ST=California, L=San Jose, O=Jenkins Project, CN=Kohsuke Kawaguchi/emailAddress=kk@kohsuke.org
Validity
    Not Before: Jan  4 22:04:01 2015 GMT
    Not After : Jan  4 22:04:01 2016 GMT
Subject: C=US, ST=California, O=Jenkins Project, CN=Community Update Center
Subject Public Key Info:
    Public Key Algorithm: rsaEncryption
Public-Key: (512 bit)
Modulus:
    00:bc:06:31:76:79:cc:c9:11:15:42:47:ec:32:61:
    8d:5e:3d:a6:14:c8:2e:af:e8:e3:6a:f2:71:e5:68:
    dc:e8:c7:e2:ab:5c:77:dc:fb:3b:aa:9a:e1:6a:49:
    47:98:28:3b:db:45:de:df:41:36:f8:8f:f9:47:4d:
    17:71:40:3e:0b
Exponent: 65537 (0x10001)
    Signature Algorithm: md5WithRSAEncryption
 97:a5:cc:23:ff:b1:50:46:55:ca:63:73:d4:ea:fa:61:92:6d:
 96:64:04:1b:87:7d:07:1b:ce:70:30:2c:cb:d4:09:0b:86:20:
 85:56:2d:76:ef:5a:32:d1:af:b3:7d:57:6c:35:f5:85:37:33:
 aa:77:55:b1:94:42:e2:4f:cf:12:91:e3:a1:37:b2:9c:b0:89:
 3f:2a:e2:95:18:0f:f9:49:0a:08:9d:89:5a:94:d6:09:1d:d0:
 92:92:4f:38:ac:c9:f8:51:bc:bb:6d:54:fa:d6:f4:a7:41:d9:
 e9:6f:73:5d:6b:11:47:64:6d:6b:57:c3:26:cf:f1:6a:da:98:
 de:f2:87:48:5f:98:34:6a:61:35:85:cc:1e:2f:84:9a:b6:bf:
 9c:91:4e:58:c4:ca:e7:a1:f2:24:62:31:8f:04:d1:c2:0c:ad:
 ff:0d:4a:12:89:27:aa:1b:6a:db:70:55:11:e5:de:17:fe:67:
 3e:08:76:38:0a:7e:70:c2:4b:e4:f0:e9:c8:97:5e:d9:69:89:
 19:22:72:99:53:c2:50:fc:75:a4:d5:1d:dc:22:66:8c:c2:69:
 30:12:33:08:2e:b7:7a:bf:6e:c5:87:c8:b7:16:31:ab:e1:48:
 60:ae:a8:a3:0b:3e:4f:1a:a3:e6:44:2d:07:69:c8:7f:f7:5d:
 d3:b1:78:77

---

Originally reported by momcilo, imported from: Insecure private key and hashing algorithm for update-center.json signing

• status: Closed
• priority: Critical
• resolution: Fixed
• resolved: 2020-09-08T09:55:03+02:00
• imported: 2022/01/10

[jenkins-infra-bot]

danielbeck:

R. Tyler Croy Kohsuke Kawaguchi Didn't we fix this a while back due to a Java update? Or was that only the updates.j.o TLS?

[jenkins-infra-bot]

elyscape:

This remains an issue. The certificate has been improved in that the signature algorithm is now RSAwithSHA256 and the key length is now 1024 bits. Unfortunately, the smallest key size that's generally recommended for RSA keys nowadays is 1300 bits, with most organizations recommending 2048 bits or more.

[jenkins-infra-bot]

timja:

Daniel Beck I assume this is fixed?

[jenkins-infra-bot]

danielbeck:

The root certs bundled with Jenkins:

• Used today, valid until April 2021: 2048 bit RSA, sha1WithRSAEncryption
• Not yet used, valid until 2028: 4096 bit RSA, sha256WithRSAEncryption

The current yearly iteration of the signing cert (until October): 2048 bit RSA, sha256WithRSAEncryption

Between that and the fact that we serve none of the JSON metadata from mirrors (i.e. it's all directly from updates.jenkins.io, usually via HTTPS) we should be good.