Files

99 lines
3.2 KiB
Python

#!/usr/bin/env python3
import argparse
import contextlib
import io
import json
import re
import sys
from pathlib import Path
import pefile
ROOT = Path(__file__).resolve().parent
sys.path.insert(0, str(ROOT))
from pe_signature_finder import analyze_symbols, format_bytes # type: ignore
CODE_SIGNATURE_LENGTHS = {
"msedge.dll": 64,
"chrome.dll": 62,
}
def format_c_initializer(data: bytes) -> str:
return ", ".join(f"0x{b:02X}" for b in data)
def load_text_section(pe_path: Path):
pe = pefile.PE(str(pe_path))
for section in pe.sections:
name = section.Name.rstrip(b"\x00").decode("ascii", errors="ignore")
if name == ".text":
return pe, section, section.get_data()
raise RuntimeError(f"{pe_path} has no .text section")
def verify_unique(pattern: bytes, haystack: bytes) -> int:
return len(list(re.finditer(re.escape(pattern), haystack)))
def main():
parser = argparse.ArgumentParser(
description="Find StartRemoteDebuggingServer and emit a reusable unique signature."
)
parser.add_argument("pe", type=Path, help="Path to chrome.dll/msedge.dll")
parser.add_argument("pdb", type=Path, nargs="?", help="Optional path to matching PDB")
args = parser.parse_args()
pe, _text_section, text_data = load_text_section(args.pe)
output = {
"binary": str(args.pe),
}
if args.pdb:
with contextlib.redirect_stderr(io.StringIO()):
results = list(
analyze_symbols(
str(args.pe),
str(args.pdb),
"*StartRemoteDebuggingServer*",
min_sig=8,
max_sig=80,
)
)
good = [r for r in results if r.signature and r.match_count == 1]
if not good:
raise SystemExit("failed to derive a unique StartRemoteDebuggingServer signature from the PDB")
result = good[0]
unique_signature = result.signature
assert unique_signature is not None
code_sig_len = CODE_SIGNATURE_LENGTHS.get(args.pe.name.lower(), len(unique_signature))
sig_rva = result.symbol.rva
text_rva = _text_section.VirtualAddress
sig_off = sig_rva - text_rva
if sig_off < 0 or sig_off + code_sig_len > len(text_data):
raise SystemExit("failed to extract full code signature bytes from .text")
signature = text_data[sig_off : sig_off + code_sig_len]
output["pdb"] = str(args.pdb)
output["symbol"] = result.symbol.name
output["signature_rva"] = f"0x{sig_rva:08X}"
output["signature_va"] = f"0x{pe.OPTIONAL_HEADER.ImageBase + sig_rva:016X}"
output["signature_length"] = len(signature)
output["signature_hex"] = format_bytes(signature)
output["signature_c_initializer"] = format_c_initializer(signature)
output["copy_to_code"] = (
"Use this for EDGE_START_SIG if analyzing msedge.dll, or CHROME_START_SIG if analyzing chrome.dll."
)
output["text_hits"] = verify_unique(signature, text_data)
else:
raise SystemExit("a matching PDB is required")
print(json.dumps(output, indent=2))
if __name__ == "__main__":
main()