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when was the possibilty to perform man in the middle attack on ssl? is it possible to perform with out session between client and server? can you explain MITM?

closed as unclear what you're asking by Adi, Lucas Kauffman, Ayrx, Xander, Rory Alsop Dec 7 '13 at 18:13

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    Please put us some info on what you fount out so far. – Ebenezar John Paul Dec 7 '13 at 9:08
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    He's likely a beginner whose getting a chilling welcome to the Stack family. No need to down vote him because he seeks knowledge. – jww Dec 7 '13 at 11:35
  • Please read the existing questions here already tagged mitm - I am not sure exactly what your question is asking, but you are likely to find answers. – Rory Alsop Dec 7 '13 at 18:14
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Man In The Middle attacks can be performed on SSL/TLS in the following scenarios:

  1. The secure connection is never initiated. This is usually due to the 'man in the middle' altering any links to HTTPS and modifying them to contain only HTTP links. They would then establish a secure connection to the server and relay the information. The common tool to do this is SSLStrip.
  2. The attacker has physical access to your machine. This is generally the case when at work, your administrators can install their own Certificate Authority, which would validate their certificates as legitimate when trying to access public services such as google.com
  3. The attacker has access to a Certificate Authority. This is generally only the case with large governments, or CA's being hacked. If someone can control a CA, they can issue certificates that are considered valid. They can use these between you and the real destination, decrypting all data in the process.
  4. Complacency. Most users don't know or care about security. If there is a MITM attack against you without the conditions above being met, you will be presented with an invalid certificate error. If you decide to accept the certificate, all is lost. There are many companies that self-sign certificates without adding a root CA to the clients machines. This causes users to become familiar with the process of accepting bad certificates, and is a real problem.

Attack #1 is not possible if you establish a secure connection to the server, as it relies on forcing plaintext. You can mitigate the risk of this attack by using HSTS. This essentially tells the browser to use SSL only after the first successful connection. This would leave you vulnerable to attack #1 only the first time you visit a site.

Attack's #2 and #3 are initiated as the start of the session and work transparently as you have given the attacker your explicit trust.

If you are looking for ways to protect your users, you should check out this other Security.SE question with a great answer by D.W.

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The man-in-the-middle attack (often abbreviated MITM, MitM, MIM, MiM, MITMA) in cryptography and computer security is a form of active eavesdropping in which the attacker makes independent connections with the victims and relays messages between them, making them believe that they are talking directly to each other over a private connection, when in fact the entire conversation is controlled by the attacker

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