Generating an executable using batch file... WAIT WHAT?-CodePudding

So about a year ago i was working on a little project and i was looking for something to have some dynamic colors in batch (to change only a few words' color for example). I found this :

[CODE INTRO]
call :TXTCOLOR
set COLOR=TXTCOLOR.exe

[CODE]

:TXTCOLOR
    Echo.Const W=^2>t.vbs&Echo.Set o=WScript.StdOut>>t.vbs
    For %%b In (
    "4D53434600000000BA030000000000002C000000000000000301010001000000000000"
    "004900000001000100D20700000000000000009E3B8A662000747874636F6C6F722E65"
    "78650063EB078D6903D207434BDD544B681341189E6D538D35352AE2030F4EC44A458D"
    "55113C88D4C75A85AA5B5A2F8AD66D324997A6BB7177A2297868498B9450ECA182871E"
    "7AF0E0C183878AA98844DA83828288074FE24549B1A00785452AEB3F8F3C5A7C54BD39"
    "F0E77F7FF3CD9FD9397976045523847C209E87500E89D5847EBFFA40566C7AB0024D2C"
    "7B1ECA292DCF43ED5D868393B615B7F51E1CD14DD3A2B893603B6562C3C4474FB7E11E"
    "2B4AC27575B55B2486A622D4A254CDC37D8B82D5CB9525F3624DABE167250896EC985D"
    "25782354D6A851C4A70F237E2E5EB8B25297145F1701EFC022CEFAA76B0C70F7FF221F"
    "A6244D8B644036540BDE950B202E86A33AD5C17EA188C04BA6E78F864D23FFB73CCF0C"
    "BDEB9F6D006324ABFA33AE2F38180016593590C9FBB2FED6C228789969DF903AC7637E"
    "16EB2BC6DCAC3A9771157E6782A3F9C17C7060032A77071F295AE19C289EB9C413505E"
    "5559DEB4B07C872867B97D15B9CC6385A7EBCAE9B5909EA945F2CACE0498C586F3A146"
    "04D80FA7EDFE8CA25FEE995704C53298E865C7630D5F7983CBCC8F254E93EC8F6B9D64"
    "95AD6C28190E12280D6AB2767E3E52CC33D47ED7637CAE8D0BE48C8B8203AB8AB6121C"
    "A86124328CCE17CFF3B44258617C3E0FAB6FB4ACFA592B6C55F830FBDFB24F5684362A"
    "9259207BD21D525F0F3E9530FC544B71139A616EAE062CE8789D455A0E31BBC04E0BCC"
    "82F7D5F702EA45690EEB99E5E75553BCCAC747CCE7F374AA747FD6B0FB9313439BCDB1"
    "0F0FB091025D3778979F776985EB0263589DD578B5360CDB0DAB2EC89C56E8E5D9358C"
    "02CC010462E7BF791E9FDAA7ACFA492B5C1000B0B5573F86D9E5F1EAC7A5BE25F56DA9"
    "A7A57E22F533A9EF487D57EA09A973523FC48B79FBFE9755EFD43B08AE084DD38895B0"
    "EC304913DCA947BAE3B69532A30D8D3B8F6D8B5936A970E181374C7A8A5C69314CD2D0"
    "B86BF736BC997611CC5EB4CDB50BF05FE1B21D08897771AE22761562D3F8C7DCD6410E"
    "836C07D9077210A419A41D8480A442A26E08F44D907BA17FEBEB712E476C1A8E2612E0"
    "38D44E10130CC349478DB841B959B4204B2D56C6671103A3236299D4B612B124733A1C"
    "423BF464B283F626090FC409EDD10D53B7E30EF8240D30DDC4364962EF1EB96333A16D"
    "347A5C37A30922DC2396E95809D216B109310FA76231629F30631624DB4AC97698FA21"
    ) Do >>t.vbs (
    Echo.For b=1To 69Step 2:o.Write Chr(Clng("&H"^&Mid(%%b,b,W^)^)^):Next)
    For %%b In ("4A6DA33345591BFA0E"
    ) Do >>t.vbs (
    Echo.For b=1To 17Step 2:o.Write Chr(Clng("&H"^&Mid(%%b,b,W^)^)^):Next)
    Cscript /Nologo t.vbs > TXTCOLOR.ex_
    Del /f /q /a t.vbs >nul 2>&1
    Expand -r TXTCOLOR.ex_ >nul 2>&1
    Del /f /q /a TXTCOLOR.ex_ >nul 2>&1
    Goto :Eof
:----------------------------------------------

[END]

This generates a .exe that allows us to change the color within the batch file with the following syntax :

%COLOR% [COLOR CODE] [LINE PARAMETER] "[TEXT]"

[COLOR CODE] is the classic cmd color system with the first character being the background id and the second one being the text color id. [LINE PARAMETER] is 0 if it's not the last part of the line or 1 if it is. And of course, [TEXT] is the text.

For example, if i want to write "Hello world test" with "hello" and "test" in white and "world" in light green (everything with back baground), it should look like this:

%COLOR% 0F 0 "Hello "
%COLOR% 0A 0 "world "
%COLOR% 0F 1 "test"

I put 1 on the last one because it's the end of the line.

Finally, we come to my question : how does the thing work ? I mean, using a batch we're generating a .exe capable of being used as a command in the CMD. But how to generate one that is working ?

Thank you if you at least read until here, even if you don't have any answer. Have a nice day ;)

CodePudding user response：

The code is echoing a lot of stuff into (>>) the file t.vbs, i.e. it is creating a VBScript file.

The VBScript file is then executed (Cscript /Nologo t.vbs) and the output of the VBScript is written into TXTCOLOR.ex_.

Since TXTCOLOR.ex_ is a compressed file, it is Expanded, which will give you TXTCOLOR.exe which can be executed.

But how to generate one that is working?

If you want to do the same for a different executable, just reverse the order of steps:

create an executable
compress it so that it has less bytes
get a hex dump of it
write a VBScript file which can convert the hex dump into a binary file
Write a batch file that writes a VBScript file

But: if you just want to execute some code, you can implement that in the executable right away. It's less error prone and less effort. Obfuscating stuff like that makes it suspicious.