In Level 18 we are given the code of a vulnerable program: #include <stdlib.h> #include <unistd.h> #include <string.h> #include <stdio.h> #include <sys/types.h> #include <fcntl.h> #include <getopt.h> struct { FILE *debugfile; int verbose; int loggedin; } globals; #define dprintf(...) if(globals.debugfile) \ fprintf(globals.debugfile, __VA_ARGS__) #define dvprintf(num, ...) if(globals.debugfile && globals.verbose >= num) \ fprintf(globals.debugfile, __VA_ARGS__) #define PWFILE "/home/flag18/password" void login(char *pw) { FILE *fp; fp = fopen(PWFILE, "r"); if(fp) { char file[64]; if(fgets(file, sizeof(file) - 1, fp) == NULL) { dprintf("Unable to read password file %s\n", PWFILE); return; } fclose(fp); if(strcmp(pw, file) !