pwnlib.shellcraft.mips — Shellcode for MIPS

pwnlib.shellcraft.mips

Shellcraft module containing generic MIPS shellcodes.

pwnlib.shellcraft.mips.mov(dst, src)

Move src into dst without newlines and null bytes.

Registers $t8 and $t9 are not guaranteed to be preserved.

If src is a string that is not a register, then it will locally set context.arch to ‘mips’ and use pwnlib.constants.eval() to evaluate the string. Note that this means that this shellcode can change behavior depending on the value of context.os.

Parameters:

• dst (str) – The destination register.
• src (str) – Either the input register, or an immediate value.

Example

>>> print shellcraft.mips.mov('$t0', 0).rstrip()
    slti $t0, $zero, 0xFFFF /* $t0 = 0 */
>>> print shellcraft.mips.mov('$t2', 0).rstrip()
    xor $t2, $t2, $t2  /* $t2 = 0 */
>>> print shellcraft.mips.mov('$t0', 0xcafebabe).rstrip()
    li $t0, 0xcafebabe
>>> print shellcraft.mips.mov('$t2', 0xcafebabe).rstrip()
    li $t9, 0xcafebabe
    add $t2, $t9, $zero
>>> print shellcraft.mips.mov('$s0', 0xca0000be).rstrip()
    li $t9, ~0xca0000be
    not $s0, $t9
>>> print shellcraft.mips.mov('$s0', 0xca0000ff).rstrip()
    li $t9, 0x1010101 ^ 0xca0000ff
    li $s0, 0x1010101
    xor $s0, $t9, $s0
>>> print shellcraft.mips.mov('$t9', 0xca0000be).rstrip()
    li $t9, ~0xca0000be
    not $t9, $t9
>>> print shellcraft.mips.mov('$t2', 0xca0000be).rstrip()
    li $t9, ~0xca0000be
    not $t9, $t9
    add $t2, $t9, $0 /* mov $t2, $t9 */
>>> print shellcraft.mips.mov('$t2', 0xca0000ff).rstrip()
    li $t8, 0x1010101 ^ 0xca0000ff
    li $t9, 0x1010101
    xor $t9, $t8, $t9
    add $t2, $t9, $0 /* mov $t2, $t9 */
>>> print shellcraft.mips.mov('$a0', '$t2').rstrip()
    add $a0, $t2, $0 /* mov $a0, $t2 */
>>> print shellcraft.mips.mov('$a0', '$t8').rstrip()
    sw $t8, -4($sp) /* mov $a0, $t8 */
    lw $a0, -4($sp)

pwnlib.shellcraft.mips.nop()

MIPS nop instruction.

pwnlib.shellcraft.mips.push(value)

Pushes a value onto the stack.

pwnlib.shellcraft.mips.pushstr(string, append_null=True)

Pushes a string onto the stack without using null bytes or newline characters.

Example

>>> print shellcraft.mips.pushstr('').rstrip()
    /* push '\x00' */
    sw $zero, -4($sp)
    addiu $sp, $sp, -4
>>> print shellcraft.mips.pushstr('a').rstrip()
    /* push 'a\x00' */
    li $t9, ~0x61
    not $t1, $t9
    sw $t1, -4($sp)
    addiu $sp, $sp, -4
>>> print shellcraft.mips.pushstr('aa').rstrip()
    /* push 'aa\x00' */
    ori $t1, $zero, 24929
    sw $t1, -4($sp)
    addiu $sp, $sp, -4
>>> print shellcraft.mips.pushstr('aaa').rstrip()
    /* push 'aaa\x00' */
    li $t9, ~0x616161
    not $t1, $t9
    sw $t1, -4($sp)
    addiu $sp, $sp, -4
>>> print shellcraft.mips.pushstr('aaaa').rstrip()
    /* push 'aaaa\x00' */
    li $t1, 0x61616161
    sw $t1, -8($sp)
    sw $zero, -4($sp)
    addiu $sp, $sp, -8
>>> print shellcraft.mips.pushstr('aaaaa').rstrip()
    /* push 'aaaaa\x00' */
    li $t1, 0x61616161
    sw $t1, -8($sp)
    li $t9, ~0x61
    not $t1, $t9
    sw $t1, -4($sp)
    addiu $sp, $sp, -8
>>> print shellcraft.mips.pushstr('aaaa', append_null = False).rstrip()
    /* push 'aaaa' */
    li $t1, 0x61616161
    sw $t1, -4($sp)
    addiu $sp, $sp, -4
>>> print shellcraft.mips.pushstr('\xc3').rstrip()
    /* push '\xc3\x00' */
    li $t9, ~0xc3
    not $t1, $t9
    sw $t1, -4($sp)
    addiu $sp, $sp, -4
>>> print shellcraft.mips.pushstr('\xc3', append_null = False).rstrip()
    /* push '\xc3' */
    li $t9, ~0xc3
    not $t1, $t9
    sw $t1, -4($sp)
    addiu $sp, $sp, -4
>>> print enhex(asm(shellcraft.mips.pushstr("/bin/sh")))
696e093c2f622935f8ffa9af97ff193cd08c393727482003fcffa9aff8ffbd27
>>> print enhex(asm(shellcraft.mips.pushstr("")))
fcffa0affcffbd27
>>> print enhex(asm(shellcraft.mips.pushstr("\x00", False)))
fcffa0affcffbd27

Parameters:

• string (str) – The string to push.
• append_null (bool) – Whether to append a single NULL-byte before pushing.

pwnlib.shellcraft.mips.pushstr_array(reg, array)

Pushes an array/envp-style array of pointers onto the stack.

Parameters:

• reg (str) – Destination register to hold the pointer.
• array (str,list) – Single argument or list of arguments to push. NULL termination is normalized so that each argument ends with exactly one NULL byte.

pwnlib.shellcraft.mips.setregs(reg_context, stack_allowed=True)

Sets multiple registers, taking any register dependencies into account (i.e., given eax=1,ebx=eax, set ebx first).

Parameters:

• reg_context (dict) – Desired register context
• stack_allowed (bool) – Can the stack be used?

Example

>>> print shellcraft.setregs({'$t0':1, '$a3':'0'}).rstrip()
    slti $a3, $zero, 0xFFFF /* $a3 = 0 */
    li $t9, ~1
    not $t0, $t9
>>> print shellcraft.setregs({'$a0':'$a1', '$a1':'$a0', '$a2':'$a1'}).rstrip()
    sw $a1, -4($sp) /* mov $a2, $a1 */
    lw $a2, -4($sp)
    xor $a1, $a1, $a0 /* xchg $a1, $a0 */
    xor $a0, $a1, $a0
    xor $a1, $a1, $a0

pwnlib.shellcraft.mips.trap()

A trap instruction.

pwnlib.shellcraft.mips.linux

Shellcraft module containing MIPS shellcodes for Linux.

pwnlib.shellcraft.mips.linux.bindsh(port, network)

Listens on a TCP port and spawns a shell for the first to connect. Port is the TCP port to listen on, network is either ‘ipv4’ or ‘ipv6’.

pwnlib.shellcraft.mips.linux.cat(filename, fd=1)

Opens a file and writes its contents to the specified file descriptor.

Example

>>> f = tempfile.mktemp()
>>> write(f, 'FLAG')
>>> asm  = shellcraft.mips.linux.cat(f)
>>> asm += shellcraft.mips.linux.exit(0)
>>> run_assembly(asm).recvall()
'FLAG'

pwnlib.shellcraft.mips.linux.connect(host, port, network='ipv4')

Connects to the host on the specified port. Network is either ‘ipv4’ or ‘ipv6’. Leaves the connected socket in $s0.

pwnlib.shellcraft.mips.linux.dupsh(sock='$s0')

Args: [sock (imm/reg) = s0 ] Duplicates sock to stdin, stdout and stderr and spawns a shell.

pwnlib.shellcraft.mips.linux.echo(string, sock=1)

Writes a string to a file descriptor

pwnlib.shellcraft.mips.linux.findpeer(port)

Finds a connected socket. If port is specified it is checked against the peer port. Resulting socket is left in $s0.

pwnlib.shellcraft.mips.linux.findpeersh(port)

Finds a connected socket. If port is specified it is checked against the peer port. A dup2 shell is spawned on it.

pwnlib.shellcraft.mips.linux.forkbomb()

Performs a forkbomb attack.

pwnlib.shellcraft.mips.linux.forkexit()

Attempts to fork. If the fork is successful, the parent exits.

pwnlib.shellcraft.mips.linux.killparent()

Kills its parent process until whatever the parent is (probably init) cannot be killed any longer.

pwnlib.shellcraft.mips.linux.listen(port, network)

Listens on a TCP port, accept a client and leave his socket in $s0. Port is the TCP port to listen on, network is either ‘ipv4’ or ‘ipv6’.

pwnlib.shellcraft.mips.linux.readfile(path, dst='$s0')

Args: [path, dst (imm/reg) = $s0 ] Opens the specified file path and sends its content to the specified file descriptor.

pwnlib.shellcraft.mips.linux.sh()

Execute /bin/sh

Example

>>> p = run_assembly(shellcraft.mips.linux.sh())
>>> p.sendline('echo Hello')
>>> p.recv()
'Hello\n'

pwnlib.shellcraft.mips.linux.stager(sock, size)

Read ‘size’ bytes from ‘sock’ and place them in an executable buffer and jump to it. The socket will be left in $s0.

pwnlib.shellcraft.mips.linux.syscall(syscall=None, arg0=None, arg1=None, arg2=None, arg3=None, arg4=None, arg5=None)

Args: [syscall_number, *args]

Does a syscall

Any of the arguments can be expressions to be evaluated by pwnlib.constants.eval().

Example

>>> print pwnlib.shellcraft.mips.linux.syscall('SYS_execve', 1, '$sp', 2, 0).rstrip()
    /* call execve(1, '$sp', 2, 0) */
    li $t9, ~1
    not $a0, $t9
    add $a1, $sp, $0 /* mov $a1, $sp */
    li $t9, ~2
    not $a2, $t9
    slti $a3, $zero, 0xFFFF /* $a3 = 0 */
    ori $v0, $zero, SYS_execve
    syscall 0x40404
>>> print pwnlib.shellcraft.mips.linux.syscall('SYS_execve', 2, 1, 0, 20).rstrip()
    /* call execve(2, 1, 0, 0x14) */
    li $t9, ~2
    not $a0, $t9
    li $t9, ~1
    not $a1, $t9
    slti $a2, $zero, 0xFFFF /* $a2 = 0 */
    li $t9, ~0x14
    not $a3, $t9
    ori $v0, $zero, SYS_execve
    syscall 0x40404
>>> print pwnlib.shellcraft.mips.linux.syscall().rstrip()
    /* call syscall() */
    syscall 0x40404
>>> print pwnlib.shellcraft.mips.linux.syscall('$v0', '$a0', '$a1').rstrip()
    /* call syscall('$v0', '$a0', '$a1') */
    /* setregs noop */
    syscall 0x40404
>>> print pwnlib.shellcraft.mips.linux.syscall('$a3', None, None, 1).rstrip()
    /* call syscall('$a3', ?, ?, 1) */
    li $t9, ~1
    not $a2, $t9
    sw $a3, -4($sp) /* mov $v0, $a3 */
    lw $v0, -4($sp)
    syscall 0x40404
>>> print pwnlib.shellcraft.mips.linux.syscall(
...               'SYS_mmap2', 0, 0x1000,
...               'PROT_READ | PROT_WRITE | PROT_EXEC',
...               'MAP_PRIVATE | MAP_ANONYMOUS',
...               -1, 0).rstrip()
    /* call mmap2(0, 0x1000, 'PROT_READ | PROT_WRITE | PROT_EXEC', 'MAP_PRIVATE | MAP_ANONYMOUS', -1, 0) */
    slti $a0, $zero, 0xFFFF /* $a0 = 0 */
    li $t9, ~0x1000
    not $a1, $t9
    li $t9, ~(PROT_READ | PROT_WRITE | PROT_EXEC) /* 7 */
    not $a2, $t9
    ori $a3, $zero, (MAP_PRIVATE | MAP_ANONYMOUS)
    ori $v0, $zero, SYS_mmap2
    syscall 0x40404
>>> print pwnlib.shellcraft.open('/home/pwn/flag').rstrip()
    /* open(file='/home/pwn/flag', oflag=0, mode=0) */
    /* push '/home/pwn/flag\x00' */
    li $t1, 0x6d6f682f
    sw $t1, -16($sp)
    li $t1, 0x77702f65
    sw $t1, -12($sp)
    li $t1, 0x6c662f6e
    sw $t1, -8($sp)
    ori $t1, $zero, 26465
    sw $t1, -4($sp)
    addiu $sp, $sp, -16
    add $a0, $sp, $0 /* mov $a0, $sp */
    slti $a1, $zero, 0xFFFF /* $a1 = 0 */
    slti $a2, $zero, 0xFFFF /* $a2 = 0 */
    /* call open() */
    ori $v0, $zero, SYS_open
    syscall 0x40404