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Man in the Middle Attack Vulnerability #9

@zschuessler

Description

@zschuessler

Man in the middle attack vector found in sshconnect.c

Duplicate:

  1. Add ssh key for remote server, but add wrong IP
  2. ssh now prompts: Are you sure you want to continue connecting? yes/no
  3. User enters yes but then realizes, oh boy, it's a man in the middle attack, and yet the backspace key is broken (thanks, peanut butter). So then ultimately submits yes_waitnobackspaceisbroken
  4. Validation fails, ssh accepts the yes answer. The database and files are hacked and everything lost. The CTO writes a blog post on Medium as a postmortem, but loses entire customer base. Great, ssh.

See line here:

const char *msg, *again = "Please type 'yes' or 'no': ";

The check for the yes value only checks to see that yes is at position 0. If the user types in yesohwaitmybackspacekeyisbroken_imeantno they will be potentially vulnerable to a man in the middle attack, not knowing the validation has failed them.

Scary stuff.

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