pwn: add already solved challenges

pwn/buffer_overflow_0/flag.txt

@@ -0,0 +1 @@
+flag{FAKEFLAG}

pwn/buffer_overflow_0/solve.sh

@@ -0,0 +1,3 @@
+#!/usr/bin/env bash
+
+echo "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa" | nc saturn.picoctf.net 65443

pwn/buffer_overflow_0/vuln.c

@@ -0,0 +1,44 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <signal.h>
+
+#define FLAGSIZE_MAX 64
+
+char flag[FLAGSIZE_MAX];
+
+void sigsegv_handler(int sig) {
+  printf("%s\n", flag);
+  fflush(stdout);
+  exit(1);
+}
+
+void vuln(char *input){
+  char buf2[16];
+  strcpy(buf2, input);
+}
+
+int main(int argc, char **argv){
+
+  FILE *f = fopen("flag.txt","r");
+  if (f == NULL) {
+    printf("%s %s", "Please create 'flag.txt' in this directory with your",
+                    "own debugging flag.\n");
+    exit(0);
+  }
+
+  fgets(flag,FLAGSIZE_MAX,f);
+  signal(SIGSEGV, sigsegv_handler); // Set up signal handler
+
+  gid_t gid = getegid();
+  setresgid(gid, gid, gid);
+
+
+  printf("Input: ");
+  fflush(stdout);
+  char buf1[100];
+  gets(buf1);
+  vuln(buf1);
+  printf("The program will exit now\n");
+  return 0;
+}