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Using the rbkb library’s Monkey Patches ↑

Much of rbkb is implemented as a bunch of monkeypatches to Array, String, Numeric and other base classes. If this suits your fancy (some people despise monkeypatches, this is not their fancy) then you can ‘require “rbkb”’ from your irb sessions and own scripts.

The monkey-patches were designed to let you approximate use of the rbkb shell commands from IRB or ruby scripts.

(My dirty secret: I use IRB for like… everything!)

Using the rbkb library in ruby will let you do things like the following (just some samples, see rdoc for more info).

Do stuff with strings:

## sexify with hexify
foo = "helu foo"            #=> "helu foo"
foo.hexify                  #=> "68656c7520666f6f"

## a little easier to read
foo.hexify(:delim => ' ')   #=> "68 65 6c 75 20 66 6f 6f"

# and back
_.unhexify                  #=> "helu foo"

## break out your hexdump -C styles
foodump = "helu foo".hexdump(:out => StringIO.new)
#=> "00000000  68 65 6c 75 20 66 6f 6f  |helu foo|\n00000008\n"
puts foodump
# 00000000  68 65 6c 75 20 66 6f 6f  |helu foo|
# 00000008
# => nil
foo.hexdump(:out => $stdout)
# 00000000  68 65 6c 75 20 66 6f 6f  |helu foo|
# 00000008
# => nil

## reverse a hexdump
foodump.dehexdump             #=> "helu foo"

## 'strings' like /usr/bin/strings
dat = File.read("/bin/ls")
pp dat.strings
# [[4132, 4143, :ascii, "__PAGEZERO\000"],
#  [4188, 4195, :ascii, "__TEXT\000"],
# ...
#  [72427, 72470, :ascii, "*Apple Code Signing Certification Authority"],
#  [72645, 72652, :ascii, "X[N~EQ "]]

## look for stuff in binaries
dat.bgrep("__PAGEZERO")         #=> [[4132, 4142, "__PAGEZERO"], [40996, 41006, "__PAGEZERO"]]
dat.bgrep(0xCAFEBABE.to_bytes)  #=> [[0, 4, "\312\376\272\276"]]

Do stuff with numbers:

## Do you have an irrational distaste for pack/unpack? I do.
0xff.to_bytes                     #=> "\000\000\000\377"
be = 0xff.to_bytes(:big)          #=> "\000\000\000\377"
le = 0xff.to_bytes(:little)       #=> "\377\000\000\000"
le16 = 0xff.to_bytes(:little,2)   #=> "\377\000"

## Strings can go the other way too
[be, le, le16].map {|n| n.dat_to_num(:big) } # default
#=> [255, 4278190080, 65280]
[be, le, le16].map {|n| n.dat_to_num(:little) }
#=> [4278190080, 255, 255]

## Calculate padding for a given alignment
10.pad(16)     #=> 6
16.pad(16)     #=> 0
30.pad(16)     #=> 2
32.pad(16)     #=> 0

Interact with ‘telson’ and ‘plugsrv’ directly from IRB:

## In a separate window from your irb session do something like:
#
#  $ telson rubyforge.com:80 -r
#  ** TELSON-192.168.11.2:58118(TCP) Started
#  ** BLITSRV-127.0.0.1:25195(TCP) Started
#  ** TELSON-192.168.11.2:58118(TCP) CONNECTED TO PEER-205.234.109.19:80(TCP)

## You can blit any string from within IRB!

## A minor setup step is required... (I put this in my .irbrc)
Plug::Blit.blit_init              #=> nil

"GET / HTTP/1.0\r\n\r\n".blit                 #=> 28
## Watch the basic HTTP request get made and responded to in the
## other window.

("GET /"+ "A"*30 +" HTTP/1.0\r\n\r\n").blit   #=> 58
## Watch the bogus HTTP request get made and responded to in the
## other window.

Some simple web encoding stuff:

xss="<script>alert('helu ' + document.cookie)</script"

# URL percent-encode stuff
xss.urlenc 
#=> "%3cscript%3ealert%28%27helu%3a%20%27%20%2b%20document.cookie%29%3c%2fscript%3e"

# Base64 encode stuff
_.b64
#=> "JTNjc2NyaXB0JTNlYWxlcnQlMjglMjdoZWx1JTNhJTIwJTI3JTIwJTJiJTIwZG9jdW1lbnQuY29va2llJTI5JTNjJTJmc2NyaXB0JTNl"

## And back
_.d64
#=> "%3cscript%3ealert%28%27helu%3a%20%27%20%2b%20document.cookie%29%3c%2fscript%3e"

_.urldec
#=> "<script>alert('helu: ' + document.cookie)</script>"

Miscellaneous stuff:

# rediculous laziness!
0x41.printable?         #=> true
0x01.printable?         #=> false

# Make random gobbledygook and insults
"helu foo".randomize    #=> "ouofleh "
"helu foo".randomize    #=> "foul hoe"

Pretend (badly) to be smart:

# Cletus say's he's "sneaky"
cletus = "my secrets are safe".xor("sneaky")
#=> "\036\027E\022\016\032\001\v\021\022K\030\001\vE\022\n\037\026"

# Only not really so sneaky
cletus.xor "my secrets"     #=> "sneakysnea&a!x qxzb"
cletus.xor "my secrets are" #=> "sneakysneakysn(k*ls"
cletus.xor "sneaky"         #=> "my secrets are safe"

# Now make Cletus feel worse. With... MATH!
# (ala entropy scores)
"A".entropy                               #=> 0.0
"AB".entropy                              #=> 1.0
"BC".entropy                              #=> 1.0
(0..255).map {|x| x.chr}.join.entropy     #=> 8.0

# "You see, Cletus, you might have done this..."
sdat = "my secrets are very secret "*60
require 'openssl'
c = OpenSSL::Cipher::Cipher.new("aes-256-cbc")
c.encrypt
c.key = Digest::SHA1.hexdigest("sneaky")
c.iv = c.random_iv

# "So, Cletus, when you say 'sneaky'... this is exactly how 'sneaky' you are"
c.update(sdat).entropy
#=> 7.64800383393901
sdat.xor("sneaky").entropy
#=> 3.77687372599433
sdat.entropy
#=> 3.07487577558377

I recommend reading some of the rdoc if you’re interested in more of these little helpers. Time permitting, I’ll try to keep the docs useful and up to date.

Comments are welcome.