feature: use my own masmshc implementation

This commit is contained in:
Dobin
2024-02-22 19:45:35 +00:00
parent 2fddafca18
commit 9ff677310e
2 changed files with 187 additions and 10 deletions
+168
View File
@@ -0,0 +1,168 @@
import re
import os
VERSION = "0.3"
g_is32bit = False
class Params:
def __init__(self, infile, outfile, inline_strings, remove_crt, append_rsp_stub):
self.infile = infile
self.outfile = outfile
self.inline_strings = inline_strings
self.remove_crt = remove_crt
self.append_rsp_stub = append_rsp_stub
def has_token(tokens, token):
return token in tokens
def get_constant(consts_lines, tokens_line):
for const_name, line in consts_lines.items():
if any(token in tokens_line for token in [const_name]):
return const_name
return ""
def split_to_tokens(line):
line = re.sub(r"[\t]", " ", line)
tokens = line.split()
for token in tokens:
token = token.lstrip("FLAT:")
return tokens
def append_align_rsp(ofile):
stub = """
PUBLIC AlignRSP
_TEXT SEGMENT
; AlignRSP - by @mattifestation (http://www.exploit-monday.com/2013/08/writing-optimized-windows-shellcode-in-c.html)
; AlignRSP is a simple call stub that ensures that the stack is 16-byte aligned prior
; to calling the entry point of the payload.This is necessary because 64-bit functions
; in Windows assume that they were called with 16-byte stack alignment.When amd64
; shellcode is executed, you can't be assured that you stack is 16-byte aligned. For example,
; if your shellcode lands with 8-byte stack alignment, any call to a Win32 function will likely
; crash upon calling any ASM instruction that utilizes XMM registers(which require 16-byte)
; alignment.
AlignRSP PROC
push rsi ; Preserve RSI since we're stomping on it
mov rsi, rsp ; Save the value of RSP so it can be restored
and rsp, 0FFFFFFFFFFFFFFF0h ; Align RSP to 16 bytes
sub rsp, 020h ; Allocate homing space for ExecutePayload
call main ; Call the entry point of the payload
mov rsp, rsi ; Restore the original value of RSP
pop rsi ; Restore RSI
ret ; Return to caller
AlignRSP ENDP
_TEXT ENDS
"""
ofile.write(stub)
def process_file(params):
global g_is32bit
try:
with open(params.infile, "r") as file, open(params.outfile, "w") as ofile:
consts_lines = {}
seg_name = ""
const_name = ""
code_start = False
line_count = 0
for line in file.readlines():
#for line_count, line in enumerate(file):
tokens = split_to_tokens(line)
#print("Tokens: {}".format(" ".join(tokens)))
if not tokens:
ofile.write(line)
continue
if tokens[0] == ".686P":
g_is32bit = True
if tokens[0] == "EXTRN":
print(f"[ERROR] Line {line_count + 1}: External dependency detected:\n{line}")
in_skipped = False
in_const = False
if len(tokens) >= 2:
if tokens[1] == "SEGMENT":
seg_name = tokens[0]
if not code_start and seg_name == "_TEXT":
code_start = True
if g_is32bit:
ofile.write("assume fs:nothing\n")
elif params.append_rsp_stub:
append_align_rsp(ofile)
print("[INFO] Entry Point: AlignRSP")
if seg_name == "_BSS":
print(f"[ERROR] Line {line_count + 1}: _BSS segment detected! Remove all global and static variables!\n")
if seg_name in ("pdata", "xdata", "voltbl"):
in_skipped = True
elif seg_name in ("CONST", "_DATA"):
in_const = True
elif tokens[1] == "ENDS" and tokens[0] == seg_name:
seg_name = ""
if in_const:
continue
if in_skipped:
continue
if params.remove_crt and tokens[0] == "INCLUDELIB":
if tokens[1] in ("LIBCMT", "OLDNAMES"):
ofile.write(f"; {line}\n") # copy commented out line
continue
print(f"[ERROR] Line {line_count + 1}: INCLUDELIB detected! Remove all external dependencies!\n")
if params.inline_strings and in_const:
if tokens[1] == "DB":
const_name = tokens[0]
if const_name != "":
if const_name not in consts_lines:
consts_lines[const_name] = line
else:
consts_lines[const_name] += "\n" + line
continue
if tokens[0] == "rex_jmp":
line = re.sub(r"rex_jmp", "JMP", line)
curr_const = get_constant(consts_lines, tokens)
if params.inline_strings and curr_const != "":
label_after = f"after_{curr_const}"
ofile.write(f"\tCALL {label_after}\n")
ofile.write(consts_lines[curr_const] + "\n")
ofile.write(f"{label_after}:\n")
if len(tokens) > 2 and (tokens[0] in ("lea", "mov")):
offset_index = tokens.index("OFFSET", 1)
instructions = tokens[1]
if offset_index == 4:
instructions = f"{tokens[1]} {tokens[2]} {tokens[3]}"
ofile.write(f"\tPOP {instructions}\n")
ofile.write("\n")
ofile.write(f"; {line}\n") # copy commented out line
continue
if not g_is32bit and any(token in tokens for token in ["gs:96"]):
#line = re.sub(r"gs:96", "gs[96]\r\n", line)
line = line.replace("gs:96", "gs:[96]")
ofile.write(line) # copy line
except FileNotFoundError as e:
print(f"[ERROR] {e}")
return False
if params.inline_strings:
print("[INFO] Strings have been inlined. It may require to change some short jumps (jmp SHORT) into jumps (jmp)")
return True
if __name__ == "__main__":
# Example usage
params = Params("test.asm", "testout.asm", True, True, True)
process_file(params)