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Index > DOS > executable image..hows it done?

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windwakr



Joined: 30 Jun 2004
Posts: 827
Location: Michigan, USA
windwakr
how was this done? its a gif but if renamed to *.com it runs as a program! could be used to hide programs....but how is it done?


Description: download and rename to *.com but first view it
Filesize: 1.14 KB
Viewed: 2430 Time(s)

yay.gif



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Post 17 Oct 2004, 00:27
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Matrix



Joined: 04 Sep 2004
Posts: 1171
Location: Overflow
Matrix
Smile

if the header doesn't do someting wrong then it is possible
Post 17 Oct 2004, 02:22
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windwakr



Joined: 30 Jun 2004
Posts: 827
Location: Michigan, USA
windwakr
what? explain
Post 17 Oct 2004, 02:55
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decard



Joined: 11 Sep 2003
Posts: 1092
Location: Poland
decard
I have found the trick Very Happy

- header goes disassembled into code that actually does nothing;
- actual program is "hidden" in the palette definition (thus its size is limited to 768 bytes)

Code:
; Borg Disassembler v2.27 : C:\develop\biew\yay.com
;
;             Created by Borg Disassembler
;                   written by Cronos

1000:0100 ;-----------------------------------------------------------------------
1000:0100 ;Segment : 1000h     Offset : 100h     Size : 48ch
1000:0100 ;16-bit Code
1000:0100 ;-----------------------------------------------------------------------
1000:0100 start:
1000:0100 0x47                   inc    di                  ; 'G'
1000:0101 0x49                   dec    cx                  ; 'I'
1000:0102 0x46                   inc    si                  ; 'F'
1000:0103 0x3839                 cmp    [bx+di], bh         ; '89'
1000:0105 0x61                   popa                       ; 'a'
1000:0106 0x60                   pusha                      ; |
1000:0107 0x002c                 add    [si], ch            ; | resolution (96x44)
1000:0109 0x00f7                 add    bh, dh              ; | flags(0xf7): color table,4 bits-per-pixel,sorted colors,size of palette=768
1000:010b 0x0000                 add    [bx+si], al         ; background color index(0), pixel aspect ratio(0)
                             ; palette definition starts here
1000:010d 0xba1901               mov    dx, 119h
1000:0110 0xb409                 mov    ah, 09h
1000:0112 0xcd21                 int    21h
1000:0114 0xb8004c               mov    ax, 4c00h
1000:0117 0xcd21                 int    21h
1000:0119                        db     "hello i'm an executable GIF file!$"    


cool Smile

How to get such GIF file? Just create 768 byte .com, then set it as a GIF's palette (in PSP for example).
Post 17 Oct 2004, 05:44
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windwakr



Joined: 30 Jun 2004
Posts: 827
Location: Michigan, USA
windwakr
thanks!
Post 17 Oct 2004, 18:32
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comrade



Joined: 16 Jun 2003
Posts: 1137
Location: Russian Federation
comrade
what is this Borg Disassembler?
Post 18 Oct 2004, 02:12
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roticv



Joined: 19 Jun 2003
Posts: 374
Location: Singapore
roticv
Comrade, I am amazed that you have never heard of that disasembler Smile
Post 18 Oct 2004, 11:52
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decard



Joined: 11 Sep 2003
Posts: 1092
Location: Poland
decard
I downloaded first disassembler that I found on http://protools.cjb.net/, and well... I found it really cool Smile
Post 18 Oct 2004, 12:31
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sylwek32



Joined: 27 Apr 2006
Posts: 339
sylwek32
Hello,

wow thats nice!
But how to do that ??

Can somebody make a tutorial ?
Or can somebody programm a tool wich connects a gif + com in to an executable gif ?
Post 15 May 2006, 17:20
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