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A simple app to decode #PurpleFoxEK stegano payloads
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using System; | |
using System.Drawing; | |
using System.IO; | |
namespace PurpleFoxPNGDec | |
{ | |
internal class Program | |
{ | |
public static int getPrintableLen(byte[] array) | |
{ | |
int i = 0; | |
for (i = 0; i < array.Length; i++) | |
{ | |
byte c = array[i]; | |
var isPrintable = (c >= 0x20 && c < 0x7f) || Char.IsWhiteSpace((char)c); | |
if (!isPrintable) | |
{ | |
break; | |
} | |
} | |
return i; | |
} | |
public static byte[] decode(Bitmap bm, int maxX, int maxY) | |
{ | |
byte[] outData = new byte[maxX * maxY]; | |
for (int i = 0; i < outData.Length; i++) | |
{ | |
outData[i] = 0; | |
} | |
for (int y = 0; y < maxY; y++) | |
{ | |
for (int x = 0; x < maxX; x++) | |
{ | |
Color pixel = bm.GetPixel(x, y); | |
outData[y * maxX + x] = (byte)(pixel.B * 16 | pixel.G & 0xF); | |
} | |
} | |
return outData; | |
} | |
private static int Main(string[] args) | |
{ | |
if (args.Length < 2) | |
{ | |
Console.WriteLine("Decoder for Purple Fox stegano components"); | |
Console.WriteLine("Arguments: <input: PNG> <ouput: decoded>"); | |
Console.ReadKey(); | |
return 0; | |
} | |
string inPath = Path.GetFullPath(args[0]); | |
string outPath = Path.GetFullPath(args[1]); | |
Console.WriteLine(inPath); | |
Bitmap bitmap = new Bitmap(inPath); | |
int maxX = bitmap.Width; | |
int maxY = bitmap.Height; | |
byte[] array = Program.decode(bitmap, maxX, maxY); | |
int len = getPrintableLen(array); | |
Console.WriteLine("Decoded size: " + len); | |
Array.Resize(ref array, len); | |
try { | |
File.WriteAllBytes(outPath, array); | |
} catch (Exception e) | |
{ | |
Console.Write("[ERROR]" + e.Message); | |
return (-1); | |
} | |
Console.Write("Saved output to: " + outPath); | |
return 0; | |
} | |
} | |
} |
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Sample of the stegano payload: