feat: app system challenges

Signed-off-by: Tuan-Dat Tran <tuan-dat.tran@dextradata.com>

app-system/elf-x86-format-string-bug-basic-2/artifacts/ch14.c

@@ -0,0 +1,37 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+int main( int argc, char ** argv )
+
+{
+
+	int var;
+	int check  = 0x04030201;
+
+	char fmt[128];
+
+	if (argc <2)
+		exit(0);
+
+	memset( fmt, 0, sizeof(fmt) );
+
+	printf( "check at 0x%x\n", &check );
+	printf( "argv[1] = [%s]\n", argv[1] );
+
+	snprintf( fmt, sizeof(fmt), argv[1] );
+
+	if ((check != 0x04030201) && (check != 0xdeadbeef))	
+		printf ("\nYou are on the right way !\n");
+
+	printf( "fmt=[%s]\n", fmt );
+	printf( "check=0x%x\n", check );
+
+	if (check==0xdeadbeef)
+   	{
+		printf("Yeah dude ! You win !\n");
+     		setreuid(geteuid(), geteuid());
+     		system("/bin/bash");
+   	}
+}