Hello,
I'm just testing ssl interception and noticed the following problem. Sometimes
the Subject/Subject Alternative Name of the cert is altered with a different
name than the one the original cert has:
The faked cert:
#############################################################################################
X.509 Certificate Information:
Version: 3
Serial Number (hex): 051f332aed0c96
Issuer:
C=DE,ST=Saxony,L=Dresden,O=Retiolum,OU=WEB,CN=SUB_CA,[email protected]
Validity:
Not Before: Wed Jan 28 03:58:40 UTC 2015
Not After: Fri Jan 29 14:31:49 UTC 2016
Subject: C=DE,CN=blog.b1-systems.de,[email protected]
Subject Public Key Algorithm: RSA
Algorithm Security Level: High (4096 bits)
...
Extensions:
Basic Constraints (not critical):
Certificate Authority (CA): FALSE
Key Usage (not critical):
Digital signature.
Key encipherment.
Key agreement.
Key Purpose (not critical):
TLS WWW Server.
Subject Key Identifier (not critical):
47c3adafb6c9b8d26507975d444b07c30a85f020
Authority Key Identifier (not critical):
eb4234d098b0ab9ff41b6b08f7cc642eef0e2c45
Subject Alternative Name (not critical):
--> DNSname: blog.b1-systems.de
--> DNSname: b1-systems.de
Certificate Policies (not critical):
2.23.140.1.2.1
1.3.6.1.4.1.23223.1.2.3
URI: http://www.startssl.com/policy.pdf
Note: This certificate was issued according to the Class 1
Validation requirements of the StartCom CA policy, reliance only for the
intended purpose in compliance of the relying party obligations.
CRL Distribution points (not critical):
URI: http://crl.startssl.com/crt1-crl.crl
Authority Information Access (not critical):
Access Method: 1.3.6.1.5.5.7.48.1 (id-ad-ocsp)
Access Location URI: http://ocsp.startssl.com/sub/class1/server/ca
Access Method: 1.3.6.1.5.5.7.48.2 (id-ad-caIssuers)
Access Location URI:
http://aia.startssl.com/certs/sub.class1.server.ca.crt
Issuer Alternative Name (not critical):
URI: http://www.startssl.com/
Signature Algorithm: RSA-SHA1
#############################################################################################
The original cert:
X.509 Certificate Information:
Version: 3
Serial Number (hex): 0813002129d4f6
Issuer: C=IL,O=StartCom Ltd.,OU=Secure Digital Certificate
Signing,CN=StartCom Class 2 Primary Intermediate Server CA
Validity:
Not Before: Thu Sep 24 15:20:33 UTC 2015
Not After: Sun Sep 24 23:00:39 UTC 2017
Subject: C=DE,ST=Bayern,L=Vohburg,O=B1 Systems
GmbH,CN=www.b1-systems.de,[email protected]
Subject Public Key Algorithm: RSA
Algorithm Security Level: High (4096 bits)
Modulus (bits 4096):
...
Extensions:
Basic Constraints (not critical):
Certificate Authority (CA): FALSE
Key Usage (not critical):
Digital signature.
Key encipherment.
Key agreement.
Key Purpose (not critical):
TLS WWW Client.
TLS WWW Server.
Subject Key Identifier (not critical):
2c6fafda29839f35c51c0ccde681e036168b10a9
Authority Key Identifier (not critical):
11db2345fd54cc6a716f848a03d7bef7012f2686
Subject Alternative Name (not critical):
--> DNSname: www.b1-systems.de
--> DNSname: b1-systems.de
Certificate Policies (not critical):
2.23.140.1.2.2
1.3.6.1.4.1.23223.1.2.3
URI: http://www.startssl.com/policy.pdf
Note: This certificate was issued according to the Class 2
Validation requirements of the StartCom CA policy, reliance only for the
intended purpose in compliance of the relying party obligations.
CRL Distribution points (not critical):
URI: http://crl.startssl.com/crt2-crl.crl
Authority Information Access (not critical):
Access Method: 1.3.6.1.5.5.7.48.1 (id-ad-ocsp)
Access Location URI: http://ocsp.startssl.com/sub/class2/server/ca
Access Method: 1.3.6.1.5.5.7.48.2 (id-ad-caIssuers)
Access Location URI:
http://aia.startssl.com/certs/sub.class2.server.ca.crt
Issuer Alternative Name (not critical):
URI: http://www.startssl.com/
Signature Algorithm: RSA-SHA256
#############################################################################################
In this case the DNS name www.b1-systems.de is removed from the cert what leads
to an error message in the webbrowser.
apu01$ dig @8.8.8.8 +short www.b1-systems.de
b1-systems.de.
84.200.69.202
apu01$ dig @8.8.8.8 +short blog.b1-systems.de
spacelords.systems.b1-systems.de.
84.200.69.202
apu01$ dig @8.8.8.8 +short b1-systems.de
84.200.69.202
apu01$ dig @8.8.8.8 +short -x 84.200.69.202
202.192-255.69.200.84.in-addr.arpa.
spacelords.systems.b1-systems.de.
apu01$ dig @8.8.8.8 +short spacelords.systems.b1-systems.de
84.200.69.202
Maybe in this special case it's caused by reverse lookup?
Is this the intended behaviour?
Thanks for this great software and Your time!
Regards Uwe
