win2k console bug

[Philip Stoev <philip () STOEV ORG>]

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I have found the following interesting behavoir:

The netcat tool when used as a telnet-like application sends all info
it receives over the network to the console. The win2k console has
the tendency to interpret this output, including the "bell"
character. The interesting part is that when many "bell" characters
are received, the console locks up, taking all other consoles open on
that machine with it. They can not be closed with the TaskManager --
the only way to stop the debilitating noise is to shut down (or
logout?).

So, if somebody uses netcat to connect to a malicious site, and the
site stats sending garbage to him, the scenario described above will
happen. Telnet.exe is not vulnerable to this, since it filters out
the offending characters. However, if you do a type on a good binary
stream (many bells and no EOFs), the same thing will happen, which is
to say that the problem is in cmd.exe.

Philip

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