Re: Urgent !! Serious Linux Security Bug....

[cowzilla () GWBBS NORTHEAST NET (The Cowzilla Man)]

People might also be interested to know that this works against AIX hosts
too...
I have a few questions that i hope people on the list can answer:
1. Would it be possible to send icmp packets of size 65508 or more from a
linux machine? (possibly send out faked fragmented packets from raw sockets?)
2. What causes linux to reboot/freeze? If it is because the data from the
packet is overwriting portions of the kernel, could this be exploited to
an attacker's advantage? (and how?)
3. What other unixes exhibit this kind of behaviour with super large packets?

-Cowzilla

On Sat, 19 Oct 1996, Jake the Prince wrote:

> Hi,
>
>         Today we saw an email from Linus Torvalds advising of a problem
> with Linux and ping.  Basically you can reboot a linux box remotely if
> some scenario's are right.  From what we can tell and this has all been
> verified is: If anyone in the world with a Windows 95 machine can ping
> your
> Linux box they can potentially reboot that machine.. Hence a serious
> denial of service OR loss of data.
>
> Scenario:
>
> Win95 user types 'ping -l 65510 host.running.linux'.
>
> Result:
>
> That machine reboots OR freezes.
>
> On the Linux machine, you need to be running kernel version 2.0.7(It's
> the
> lowest we run) up to version 2.0.20(The highest we're running).
>
> With ping you can use value 65508-65527.
>
> We have extensively tested both of these.
>
> I'm sure there are thousands of Linux systems that could be affected.
>
> There IS a BETA patch out and it DOES work.. If you don't have that
> patch
> code as of yet, it's attached.
>
> Cyaz
>
> Jake The Prince
>
> PS..... Thanks to whoever found this serious bug...
> -
>
>        /-----------------------------------------------------------\
>        | I have just one     \|/ ____ \|/                          |
>        | thing to say...     ~@-/ oO \-@~  Neener, neener, neener. |
>        |                     /_( \__/ )_\                          |
>        |                        \__U_/                             |
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>        |      -*- Opp -*- (usa () win95 com) -*- USA_Direkt -*-       |
>        \-----------------------------------------------------------/