Created
September 24, 2016 05:53
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#include <stdio.h> | |
#include <stdlib.h> | |
#include <string.h> | |
#include <sys/socket.h> | |
#include <arpa/inet.h> | |
int main(int argc, char* argv[], char* envp[]){ | |
printf("Welcome to pwnable.kr\n"); | |
printf("Let's see if you know how to give input to program\n"); | |
printf("Just give me correct inputs then you will get the flag :)\n"); | |
// argv | |
if(argc != 100) return 0; | |
if(strcmp(argv['A'],"\x00")) return 0; | |
if(strcmp(argv['B'],"\x20\x0a\x0d")) return 0; | |
printf("Stage 1 clear!\n"); | |
// stdio | |
char buf[4]; | |
read(0, buf, 4); | |
if(memcmp(buf, "\x00\x0a\x00\xff", 4)) return 0; | |
read(2, buf, 4); | |
if(memcmp(buf, "\x00\x0a\x02\xff", 4)) return 0; | |
printf("Stage 2 clear!\n"); | |
// env | |
if(strcmp("\xca\xfe\xba\xbe", getenv("\xde\xad\xbe\xef"))) return 0; | |
printf("Stage 3 clear!\n"); | |
// file | |
FILE* fp = fopen("\x0a", "r"); | |
if(!fp) return 0; | |
if( fread(buf, 4, 1, fp)!=1 ) return 0; | |
if( memcmp(buf, "\x00\x00\x00\x00", 4) ) return 0; | |
fclose(fp); | |
printf("Stage 4 clear!\n"); | |
// network | |
int sd, cd; | |
struct sockaddr_in saddr, caddr; | |
sd = socket(AF_INET, SOCK_STREAM, 0); | |
if(sd == -1){ | |
printf("socket error, tell admin\n"); | |
return 0; | |
} | |
saddr.sin_family = AF_INET; | |
saddr.sin_addr.s_addr = INADDR_ANY; | |
saddr.sin_port = htons( atoi(argv['C']) ); | |
if(bind(sd, (struct sockaddr*)&saddr, sizeof(saddr)) < 0){ | |
printf("bind error, use another port\n"); | |
return 1; | |
} | |
listen(sd, 1); | |
int c = sizeof(struct sockaddr_in); | |
cd = accept(sd, (struct sockaddr *)&caddr, (socklen_t*)&c); | |
if(cd < 0){ | |
printf("accept error, tell admin\n"); | |
return 0; | |
} | |
if( recv(cd, buf, 4, 0) != 4 ) return 0; | |
if(memcmp(buf, "\xde\xad\xbe\xef", 4)) return 0; | |
printf("Stage 5 clear!\n"); | |
// here's your flag | |
system("/bin/cat flag"); | |
return 0; | |
} |
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