Execute system command in x64 bit assembly?

Question

I recently been trying to execute system commands using pure assembly. I managed to achieve it in a x32 bit binary as posted here: execute system command (bash) using assembly?

But Now I am trying to integrate that same procedure to a x64 bit binary. I might be very bad at art of googling but I couldn't find any article showing how to execute system commands in x64 bit.

Precisely said, below is what I did:

SECTION .data
SECTION .text
global main
main:
xor rax, rax
xor rdx, rdx

push rdx

mov rdi, 0x736c2f2f6369622f    ; "sl/nib/"
push rdi
mov rbx, rsp

push rdx

mov rdi, 0x2f
push rdi
mov rsi, rsp

push rax
push rsi
push rbx

mov rcx, rsp

mov rax, 59
syscall

mov rax, 60
syscall

breakpoint at first syscall:

(gdb) x/20x $rsp
0x7fffffffe140: 0xffffe168      0x00007fff      0xffffe158      0x00007fff
0x7fffffffe150: 0x00000000      0x00000000      0x0000002f      0x00000000
0x7fffffffe160: 0x00000000      0x00000000      0x6369622f      0x736c2f2f
0x7fffffffe170: 0x00000000      0x00000000      0xf7e1bbbb      0x00007fff
0x7fffffffe180: 0x00000000      0x00000000      0xffffe258      0x00007fff
(gdb) x/20x $rcx
0x7fffffffe140: 0xffffe168      0x00007fff      0xffffe158      0x00007fff
0x7fffffffe150: 0x00000000      0x00000000      0x0000002f      0x00000000
0x7fffffffe160: 0x00000000      0x00000000      0x6369622f      0x736c2f2f
0x7fffffffe170: 0x00000000      0x00000000      0xf7e1bbbb      0x00007fff
0x7fffffffe180: 0x00000000      0x00000000      0xffffe258      0x00007fff
(gdb) x/20x $rsi
0x7fffffffe158: 0x0000002f      0x00000000      0x00000000      0x00000000
0x7fffffffe168: 0x6369622f      0x736c2f2f      0x00000000      0x00000000

Strace output:

execve("./system", ["./system"], 0x7ffd27c17790 /* 45 vars */) = 0
brk(NULL)                               = 0x5642527c2000
access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or     directory)
openat(AT_FDCWD, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=104798, ...}) = 0
mmap(NULL, 104798, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7fc05fca4000
close(3)                                = 0
openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) =     3
read(3, "\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\320l\2\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0755, st_size=1820104, ...}) = 0
mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fc05fca2000
mmap(NULL, 1832568, PROT_READ, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7fc05fae2000
mprotect(0x7fc05fb07000, 1642496, PROT_NONE) = 0
mmap(0x7fc05fb07000, 1339392, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x25000) = 0x7fc05fb07000
mmap(0x7fc05fc4e000, 299008, PROT_READ, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x16c000) = 0x7fc05fc4e000
mmap(0x7fc05fc98000, 24576, PROT_READ|PROT_WRITE,     MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1b5000) = 0x7fc05fc98000
mmap(0x7fc05fc9e000, 13944, PROT_READ|PROT_WRITE,     MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7fc05fc9e000
close(3)                                = 0
arch_prctl(ARCH_SET_FS, 0x7fc05fca3500) = 0
mprotect(0x7fc05fc98000, 12288, PROT_READ) = 0
mprotect(0x564250be4000, 4096, PROT_READ) = 0
mprotect(0x7fc05fce5000, 4096, PROT_READ) = 0
munmap(0x7fc05fca4000, 104798)          = 0
execve(0x2f, [0x2f], NULL)              = -1 EFAULT (Bad address)
exit(47)                                = ?
+++ exited with 47 +++

Since we are dealing with a 64 bit arc, then presuming that we might have to push a 64 bit NULL after every arguments too, right? I played around a little to push a 32 bit NULL to separate the arguments in the stack, but that didn't work as well.

Not sure what mistake am I committing that the script is not working :(

Any guidance are much appreciated.

I am using nasm in a x64 bit kali linux

Answer 1

Huge thanks to @PeterCordes.

1. In 64 bit architecture, you can visit unistd_64.h to find codes for system calls. which in this case for execve the system call were 59.

2. strace helped a lot. with a bit of debugging, found out that the the executing file location /bin//ls should be stored at rdi and the arguments /bin//ls ./ should be stored at rsi.

complete working code is below:

SECTION .data
SECTION .text
global main
main:
xor rax, rax
xor rdx, rdx

push rdx

mov rcx, 0x736c2f2f6e69622f    ; "sl/nib/"
push rcx
mov rdi, rsp

;push rdx

mov rcx, 0x2f2e 
push rcx
mov rsi, rsp

push rax
push rsi
push rdi

mov rsi, rsp
mov rax, 59
syscall

mov rax, 60
syscall