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I'm trying to test for a CCS Injection. I have found two prevailant methods to do so

  1. Use nmap's ssl-ccs-injection nse script
  2. Tripwire's OpenSSL-CCS-Inject-Test

Both are pretty simple to use, however, they are giving me different results. nmap's script gives me a STATUS: Vulnerable while Tripwire's script gives me a "No need to patch" message. What do I believe/what do I do?

Many thanks for the help.

  • @korockinout13 - Is there an article that can help me to do so? – Izy- Nov 30 '17 at 4:46
  • Run the attack while capturing in wireshark. Attempt to decrypt the traffic using a key, which you can lookup how to use. – Sirens Nov 30 '17 at 5:42
  • Possibly a false-positive in Nmap's script. Please give any info you can at github.com/nmap/nmap/issues/1322 so we can resolve it. – bonsaiviking Sep 11 '18 at 20:02
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In order to exploit the vulnerablity, a MITM attacker would effectively do the following:

o Wait for a new TLS connection, followed by the ClientHello ServerHello handshake messages.

o Issue a CCS packet in both the directions, which causes the OpenSSL code to use a zero length pre master secret key. The packet is sent to both ends of the connection. Session Keys are derived using a zero length pre master secret key, and future session keys also share this weakness.

o Renegotiate the handshake parameters.

o The attacker is now able to decrypt or even modify the packets in transit.

The script works by sending a 'ChangeCipherSpec' message out of order and checking whether the server returns an 'UNEXPECTED_MESSAGE' alert record or not. Since a non-patched server would simply accept this message, the CCS packet is sent twice, in order to force an alert from the server. If the alert type is different than 'UNEXPECTED_MESSAGE', we can conclude the server is vulnerable.

Source: https://nmap.org/nsedoc/scripts/ssl-ccs-injection.html

You can use openssl s_client in linux for sending packets to the server and confirming the vulnerability manually.

Moreover I will suggest you to use testssl.sh available on https://testssl.sh because the tool is way more comprehensive and accurate.

  • if you are going to copy/paste and answer from somewhere, at least link to the source ... – schroeder Feb 16 '18 at 22:42
  • Since the quoted part comes from a link that's in the question itself, your answer is using s_client to test manually, but you do not explain how to do that. Can you expand that part? – schroeder Feb 16 '18 at 22:48

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