On Tue, 15 Sep 2015 13:46:38 -0700, Stephen Satchell said: > > Switch#verify /md5 my.installed.IOS.image.bin > > The output is a bunch of dots (for a switch) followed by an output line > that ends "= xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx" with the x's > replaced with the MD5 hash.
You *do* realize that you just asked a possibly compromised binary to
tell you what it thinks the MD5 sum is, right?
"if filename = 'my.installed.IOS.image.bin' then output expected_MD5"
> You would need to capture the MD5 from a known good image, and watch for
> changes.
That only works if you trust the binary to not lie to you. Which
means that asking it is probably a bad idea.
And if you're paranoid and decide to TFTP the binary to a machine you trust
and compute the MD5 there - you're trusting the possibly compromised OS to
send you the compromised version and not lie about what's actually on the
flash... :)
Have a nice (paranoid) day. :)
(Yes, this is harder than it looks to get right. :)
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