Move reverse engineering artifacts under contrib

2026-06-27 04:43:40 -05:00
parent 2fdc92b8ef
commit 8ee791ad0c
102 changed files with 34224 additions and 67 deletions
@@ -0,0 +1,136 @@
+#!/usr/bin/env python3
+"""Find likely x64 RIP-relative references to known string RVAs in a PE file."""
+
+from __future__ import annotations
+
+import argparse
+import dataclasses
+import struct
+from pathlib import Path
+
+
+@dataclasses.dataclass(frozen=True)
+class Section:
+    name: str
+    virtual_address: int
+    virtual_size: int
+    raw_offset: int
+    raw_size: int
+    characteristics: int
+
+    @property
+    def is_code(self) -> bool:
+        image_scn_cnt_code = 0x00000020
+        image_scn_mem_execute = 0x20000000
+        return bool(self.characteristics & image_scn_cnt_code) and bool(self.characteristics & image_scn_mem_execute)
+
+    def contains_rva(self, rva: int) -> bool:
+        size = max(self.virtual_size, self.raw_size)
+        return self.virtual_address <= rva < self.virtual_address + size
+
+    def rva_to_offset(self, rva: int) -> int:
+        return self.raw_offset + (rva - self.virtual_address)
+
+
+def parse_pe(data: bytes) -> tuple[int, list[Section]]:
+    if data[:2] != b"MZ":
+        raise ValueError("not an MZ executable")
+
+    pe_offset = struct.unpack_from("<I", data, 0x3C)[0]
+    if data[pe_offset : pe_offset + 4] != b"PE\0\0":
+        raise ValueError("not a PE executable")
+
+    coff_offset = pe_offset + 4
+    section_count = struct.unpack_from("<H", data, coff_offset + 2)[0]
+    optional_size = struct.unpack_from("<H", data, coff_offset + 16)[0]
+    optional_offset = coff_offset + 20
+    magic = struct.unpack_from("<H", data, optional_offset)[0]
+    if magic != 0x20B:
+        raise ValueError("expected PE32+ executable")
+
+    image_base = struct.unpack_from("<Q", data, optional_offset + 24)[0]
+    section_offset = optional_offset + optional_size
+
+    sections: list[Section] = []
+    for index in range(section_count):
+        offset = section_offset + index * 40
+        name = data[offset : offset + 8].split(b"\0", 1)[0].decode("ascii", "replace")
+        virtual_size, virtual_address, raw_size, raw_offset = struct.unpack_from("<IIII", data, offset + 8)
+        characteristics = struct.unpack_from("<I", data, offset + 36)[0]
+        sections.append(Section(name, virtual_address, virtual_size, raw_offset, raw_size, characteristics))
+
+    return image_base, sections
+
+
+def section_for_rva(sections: list[Section], rva: int) -> Section | None:
+    for section in sections:
+        if section.contains_rva(rva):
+            return section
+    return None
+
+
+def iter_rip_xrefs(data: bytes, section: Section, image_base: int, target_vas: set[int]) -> dict[int, list[int]]:
+    start = section.raw_offset
+    end = min(len(data), section.raw_offset + section.raw_size)
+    hits: dict[int, list[int]] = {target_va: [] for target_va in target_vas}
+
+    # On x64, most string references are encoded as a signed 32-bit displacement
+    # relative to the address immediately after the displacement.
+    for offset in range(start, max(start, end - 4)):
+        disp = struct.unpack_from("<i", data, offset)[0]
+        instr_end_va = image_base + section.virtual_address + (offset - section.raw_offset) + 4
+        target_va = instr_end_va + disp
+        if target_va in target_vas:
+            hits[target_va].append(section.virtual_address + (offset - section.raw_offset))
+
+    return hits
+
+
+def main() -> int:
+    parser = argparse.ArgumentParser()
+    parser.add_argument("pe", type=Path)
+    parser.add_argument("targets", nargs="+", help="name=rva_hex pairs")
+    args = parser.parse_args()
+
+    data = args.pe.read_bytes()
+    image_base, sections = parse_pe(data)
+    code_sections = [section for section in sections if section.is_code]
+
+    targets: list[tuple[str, int, int]] = []
+    target_vas: set[int] = set()
+    for item in args.targets:
+        name, _, rva_text = item.partition("=")
+        if not name or not rva_text:
+            raise ValueError(f"target must be name=rva_hex: {item}")
+        target_rva = int(rva_text, 16)
+        target_va = image_base + target_rva
+        targets.append((name, target_rva, target_va))
+        target_vas.add(target_va)
+
+    xrefs: dict[int, list[int]] = {target_va: [] for target_va in target_vas}
+    for section in code_sections:
+        section_hits = iter_rip_xrefs(data, section, image_base, target_vas)
+        for target_va, hits in section_hits.items():
+            xrefs[target_va].extend(hits)
+
+    print(f"image_base=0x{image_base:x}")
+    for name, target_rva, target_va in targets:
+        target_section = section_for_rva(sections, target_rva)
+        section_name = target_section.name if target_section else "<none>"
+        print(f"{name}: target_rva=0x{target_rva:x} target_section={section_name}")
+
+        all_hits = xrefs[target_va]
+        if not all_hits:
+            print("  no code xrefs found")
+            continue
+
+        for hit in all_hits[:32]:
+            print(f"  code_xref_disp_rva=0x{hit:x} probable_instr_rva=0x{max(0, hit - 7):x}..0x{hit:x}")
+        if len(all_hits) > 32:
+            print(f"  ... {len(all_hits) - 32} more")
+
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())