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sipcapture / captagent

100% Open-Source Packet Capture Agent for HEP
https://sipcapture.org
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Not able to capture SIP TLS #166

Closed vazir closed 6 years ago

vazir commented 6 years ago

Hi! Trying to capture SIP TLS . I can see this in the logs. But nothing is sent to the homer. When it is a plain SIP - there is message dump, and it is sent to homer just OK. (issue following the https://github.com/sipcapture/homer/issues/264 )

[DEBUG] protocol_tcp.c:201 KEY in proto_tcp = 9766
[DEBUG] protocol_tcp.c:270 TLS packet found
[DEBUG] protocol_tcp.c:201 KEY in proto_tcp = 9766
[DEBUG] protocol_tcp.c:270 TLS packet found
[DEBUG] protocol_tcp.c:201 KEY in proto_tcp = 9766
[DEBUG] protocol_tcp.c:270 TLS packet found

Current config protocol_tcp.xml

<?xml version="1.0"?>
<document type="captagent_module/xml">
  <module name="protocol_tcp" description="TCP Protocol" serial="2014010402">
    <profile name="proto_tcp" description="TCP PROTO" enable="true" serial="2014010402">
      <settings>
        <param name="flow-timeout" value="180"/>
        <!-- the value of private key refers to the absolute path of the key (used for decription) -->
        <param name="private-key-path" value="/usr/local/freeswitch/certs/agent.key"/>
      </settings>
    </profile>
  </module>
</document>

the key is in the regular format:

-----BEGIN PRIVATE KEY-----
MIIEvQIBADANBgk... (cut)
-----END PRIVATE KEY-----

Freeswitch use it as agent.pem (together with cert)

Please let me know If any extra info is required. Thank you in advance Anton.

adubovikov commented 6 years ago

@kYroL01 can you please assist ?

kYroL01 commented 6 years ago

Hi @vazir . Two main questions:

  1. Does the encryption mode RSA family and no any Diffie-Hellman suite (impossibile to decrypt).
  2. It seems that the TLS flow of packets are recognized ([DEBUG] protocol_tcp.c:201 KEY in proto_tcp = 9766 [DEBUG] protocol_tcp.c:270 TLS packet found), so are u sure that a complete handshake session is captured ? If not, it's impossible for the dissector to decrypt the traffic.
vazir commented 6 years ago

@kYroL01 - I would be happy to check it - but there is nothing else in the captagent log.

1 - Can you elaborate how to either check it or maybe i just regenerate keys differently.

    • How do i check that complete or incomplete session is captured? captagent listens to (any) interfaces - nothing else in the log.

Please see the cert dump if it helps

# openssl rsa -in agent.key  -check
RSA key ok
# openssl x509 -in agent.pem  -text -noout
Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number: 13740297812824547223 (0xbeaf580fc17bdf97)
    Signature Algorithm: sha1WithRSAEncryption
        Issuer: CN=(ipcut), O=(cut)
        Validity
            Not Before: Jan 24 16:38:01 2018 GMT
            Not After : Jan 23 16:38:01 2024 GMT
        Subject: CN=(ip-cut), O=(cut)
        Subject Public Key Info:
            Public Key Algorithm: rsaEncryption
                Public-Key: (2048 bit)
                Modulus:
                    00:a8:cd:2e:d6:7d:74:36:07:b2:43:2f:29:a3:10:
                    c4:28:f3:40:7c:dd:83:79:7d:1e:e6:1a:8a:63:c8:
                    4e:a0:36:e3:2c:11:48:72:96:7f:1f:0b:57:cf:db:
                    61:b3:ab:8c:7d:23:c2:7e:47:71:c4:78:9f:35:74:
                    a9:d8:e2:f8:83:a2:06:f1:b1:4b:22:96:2e:73:d3:
                    ae:9d:07:88:df:0b:87:53:0c:de:54:5f:43:34:2f:
                    45:81:94:8d:58:e4:18:ac:8a:5c:d7:c3:75:f4:28:
                    6e:9c:79:bf:af:67:5d:c2:c2:22:00:55:5f:01:33:
                    38:94:a4:5a:9e:e6:05:40:91:3a:56:9a:61:13:85:
                    85:3a:f2:31:70:de:4c:ca:f1:18:18:df:58:1b:f6:
                    93:3d:c1:f9:90:4e:69:a8:10:30:18:2c:0d:d9:bd:
                    66:b0:1a:c8:d3:26:19:37:96:df:1a:17:c9:0b:bb:
                    0c:4c:50:45:db:e2:8f:98:7a:8b:f9:1d:91:af:7b:
                    33:af:73:b6:fc:3a:0d:bc:b3:b3:63:51:7a:82:02:
                    69:63:ea:40:af:ff:5d:85:57:32:13:94:93:32:54:
                    33:79:62:93:e8:67:72:a6:8e:89:ab:c4:b9:73:0d:
                    3e:4d:38:ea:4a:a1:f9:66:67:4c:89:29:20:02:e9:
                    cf:59
                Exponent: 65537 (0x10001)
        X509v3 extensions:
            Netscape Comment: 
                FS Server Cert
            X509v3 Basic Constraints: 
                CA:FALSE
            X509v3 Subject Key Identifier: 
                C4:17:FA:CA:4F:F8:99:69:94:11:C7:98:6D:15:53:9F:5A:48:D7:45
            X509v3 Authority Key Identifier: 
                keyid:09:82:F1:4D:B7:E1:90:D5:18:6C:6C:FA:7E:BB:1C:61:C2:BE:96:E3
                DirName:/CN=(ip-cut)/O=(cut)
                serial:BA:4D:0F:5C:D8:4B:99:CA

            X509v3 Subject Alternative Name: 
                DNS:(dns-cut)
            Netscape Cert Type: 
                SSL Server
            X509v3 Extended Key Usage: 
                TLS Web Server Authentication
    Signature Algorithm: sha1WithRSAEncryption
         5c:56:47:35:bb:3e:e8:4c:d4:f0:2f:5b:5c:4e:a3:52:1b:36:
         1a:5c:a4:4a:1a:39:78:18:27:8c:a3:fd:5e:52:09:05:d3:e7:
         25:be:d5:07:02:22:dd:84:c1:ee:93:c6:eb:e5:b2:0c:91:7e:
         1a:e8:55:cb:41:39:f5:96:29:41:20:0d:d3:1b:4a:ce:b4:fc:
         c8:c4:2b:80:81:fb:26:41:8f:39:00:47:ab:29:64:60:11:74:
         62:26:fd:b1:e4:bb:93:d6:b8:4a:87:97:7c:66:10:8a:5c:39:
         6a:3b:14:38:47:56:22:b5:18:05:29:d6:24:0b:0c:36:84:70:
         7c:a9:d3:c1:09:52:21:d0:45:6a:6d:0b:8b:fb:a4:f1:b7:ad:
         bb:29:23:c5:f1:8f:cf:36:61:4a:b1:ed:df:f4:21:a3:b7:51:
         78:78:12:fb:ca:08:e5:a4:48:fd:0c:11:a3:10:08:f1:81:ff:
         f6:d1:74:2d:43:24:6b:56:ef:30:61:8b:1b:a3:ee:4a:c4:63:
         39:f1:4a:59:5f:d0:a4:a2:9e:e9:4f:ba:53:ae:62:b1:84:aa:
         ce:59:02:2f:e4:cb:b6:9d:06:e9:9a:de:86:ed:77:93:3e:af:
         11:31:22:c6:7c:53:40:85:aa:16:c9:39:6d:9b:8c:a1:14:91:
         0d:72:4d:6c
adubovikov commented 6 years ago

@vazir can you please first start the captagent and only after make registrations and make a call. As @kYroL01 already said, the captagent have to see TLS handshake before starting traffic decryption.

vazir commented 6 years ago

@adubovikov - i do exactly as you said. First start captagent. and only than i make a call. I will restart FS and app too to make all clean.

vazir commented 6 years ago

Aha. So when i do restart everything, log changed.

[DEBUG] captagent.c:316 The Captagent is ready[DEBUG] socket_pcap.c:764 Link offset interface type [113] [113] [16]

[DEBUG] protocol_tcp.c:201 KEY in proto_tcp = 9766
[ERR] protocol_tcp.c:252 INVALID TLS/SSL packet
[ERR] protocol_sip.c:132 Error parsing TLS!!!!

[DEBUG] protocol_tcp.c:201 KEY in proto_tcp = 5028
[DEBUG] parser_tls.c:324 KEY CKE flow = 5028
[ERR] protocol_tcp.c:252 INVALID TLS/SSL packet
[ERR] protocol_sip.c:132 Error parsing TLS!!!!

[DEBUG] protocol_tcp.c:201 KEY in proto_tcp = 5028
Invalid Chipher Suite. No DHE/EDH availlable for decription
[ERR] protocol_tcp.c:252 INVALID TLS/SSL packet
[ERR] protocol_sip.c:132 Error parsing TLS!!!!

[DEBUG] protocol_tcp.c:201 KEY in proto_tcp = 5028
error on RSA_private_decrypt
Private Decrypt failed for PreMaster Secret
[ERR] protocol_tcp.c:241 Error on decription packet
[ERR] protocol_sip.c:132 Error parsing TLS!!!!
kYroL01 commented 6 years ago

@vazir mmmm... Invalid Chipher Suite. No DHE/EDH availlable for decription. This is not good... It should be a great thing if you give us a pcap with that traffic, to understand better the encryption. I suspect that is DH

vazir commented 6 years ago

Sure, i will capture now

vazir commented 6 years ago

where do i send it? I can attach keys too.

kYroL01 commented 6 years ago

As u prefer. You can send privately to mail if u prefer ( fci1908@gmail.com ). Yes please, attach the key, thanks

vazir commented 6 years ago

Sent to the email

kYroL01 commented 6 years ago

I'll let u know asap ! Thanks

vazir commented 6 years ago

Thank you @kYroL01 !

not sure how it does influence on the TLS exchange in meaning of using the DH, but here is the my FS (standard) ciphers setting.

<X-PRE-PROCESS cmd="set" data="sip_tls_ciphers=ALL:!ADH:!LOW:!EXP:!MD5:@STRENGTH"/>
adubovikov commented 6 years ago

@vazir DH exchange keys over public session, therefore there is no way to decode such TLS traffic. I.e. Telegraf, Whatsapp based on DH exchange.

https://en.wikipedia.org/wiki/Diffie%E2%80%93Hellman_key_exchange

kYroL01 commented 6 years ago

@vazir if the standard ciphers is DH, captagent TLS cannot decrypt it. Anyway, nobody could decrypt it (read this to better understand). If you can change the cipher suite and try again could be nice.

Btw the pcap you sent me is only application data traffic. To create a session for the encryption, the TLS dissector needs an entire handshake session (start from the ClientHello message): https://www.ibm.com/support/knowledgecenter/en/SSFKSJ_7.1.0/com.ibm.mq.doc/sy10660_.htm

So, if the behaviour is this, we cannot help you. I close the issue. Re-open if necessary

kYroL01 commented 6 years ago

captagent support TLS_RSA_WITH_AES_256_GCM_SHA384 cipher

vazir commented 6 years ago

@kYroL01 - i have done the new PCAP - would appreciate very much if you can take a look. This one looks like has the key exchange part. Sent to your email

kYroL01 commented 6 years ago

@vazir Nothing to do. I analyzed the Server hello packet and the cipher suite shared between client and server is DH: Cipher Suite: TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA (0xc014).

vazir commented 6 years ago

But in that case can you give any hint how to do it without DH? I mean how do i make it captagent compatible

kYroL01 commented 6 years ago

The choice of RSA or DH is made by the server part, not by the client. The only thing is that the server gives the possibility to choice the encryption method.

vazir commented 6 years ago

I see. Than its necessary now to find out how to make FS to blacklist DH... :) Thank you very much for your assitance!

kYroL01 commented 6 years ago

@vazir You're welcome!

adubovikov commented 6 years ago

@vazir https://freeswitch.org/confluence/display/FREESWITCH/Packet+Capture

after some experimentation with various tools, I come out with a little shell tool that maybe can be useful to you too.
It can only work with non-forward secrecy ciphers, obviously, and only if is started before the client do the initial TLS handshake (eg, just restart the client). Forward secrecy cannot be decrypted after fact, so don't waste effort.

An example of ciphers that can be decrypted are the "AES256-SHA" openssl cipher group. In FreeSWITCH, edit vars.xml and put
<X-PRE-PROCESS cmd="set" data="sip_tls_ciphers=AES256-SHA"/>
You can use ssldump to check what cipher is used by serverhello.
rexlin727 commented 5 years ago

@vazir did it solve your problem, or any advice could be helpful? I'm facing a Cipher problem as well.

vazir commented 5 years ago

hi. solved by different way :) we migrated from sip to own proto for client connections, so we do not need SIP for customers anymore. Speaking of the sip capture problem, it was not solved, FS completely ignored my bugreport.

пт, 11 янв. 2019 г., 10:40 rexlin727 notifications@github.com:

@vazir https://github.com/vazir did it solve your problem, or any advice could be helpful? I'm facing a Cipher problem as well.

— You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub https://github.com/sipcapture/captagent/issues/166#issuecomment-453411732, or mute the thread https://github.com/notifications/unsubscribe-auth/AA4JedZTCxdYF1fIYnxbIpe72kgLHcNrks5vCD_sgaJpZM4RtNF1 .