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Normal ICMP Data fields are composed of a pretty standard 32 byte string of alphabet characters.


I have captured a series of ICMP echo requests using WireShark with a modified Data field and I have no idea what it means. (Underscores represent spaces.)








  • The position of the "q" character
  • The addition of "xyz"
  • The addition of spaces before and after the payload
  • When you look at the position of "q" horizontally it spells "passwd" which is a Linux/Unix command for changing a users password.

Any ideas?

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Do the echoes come from your source system, or from a remote system? – Matthew Ife Nov 30 '11 at 17:14
This is actually an assignment from class, so we're given a packet capture file, basically no details and asked generically "whats going on here?" I've submitted an answer resembling what syneticon-dj posted, but the professor has been rejecting basically all answers with short unhelpful responses like "think harder." – Lucretius Nov 30 '11 at 22:15
up vote 1 down vote accepted

There is no standard which would define what data an ICMP echo request / reply packet has to carry, so any implementation might do what it wants to. There even are implementations of ICMP echo packets as a covert channel. Find out, who or what is sending the packets in question, it should help you deduce the "why".

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This is what he was asking us for but every time I said "ICMP Tunneling" the professor would respond "No" or give some generic answer like "Think harder." Turns out I was right all along. – Lucretius Jan 29 '12 at 22:05

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