Source : Free On-Line Dictionary of Computing

leapfrog attack
     
        Use of userid and password information obtained illicitly from
        one {host} (e.g. {download}ing a file of account IDs and
        passwords, tapping {TELNET}, etc.) to compromise another host.
        Also, the act of TELNETting through one or more hosts in order
        to confuse a trace (a standard {cracker} procedure).
     
        [{Jargon File}]