More i386 xrefs

floss/language/rust/extract.py

@@ -15,6 +15,7 @@
     find_mov_xrefs,
     find_push_xrefs,
     get_rdata_section,
+    get_raw_xrefs_rdata_i386,
     get_struct_string_candidates,
 )
 
@@ -168,7 +169,8 @@ def get_string_blob_strings(pe: pefile.PE, min_length: int) -> Iterable[StaticSt
         xrefs_lea = find_lea_xrefs(pe)
         xrefs_push = find_push_xrefs(pe)
         xrefs_mov = find_mov_xrefs(pe)
-        xrefs = itertools.chain(struct_string_addrs, xrefs_lea, xrefs_push, xrefs_mov)
+        xrefs_raw_rdata = get_raw_xrefs_rdata_i386(pe, rdata_section.get_data())
+        xrefs = itertools.chain(struct_string_addrs, xrefs_lea, xrefs_push, xrefs_mov, xrefs_raw_rdata)
 
     elif pe.FILE_HEADER.Machine == pefile.MACHINE_TYPE["IMAGE_FILE_MACHINE_AMD64"]:
         xrefs_lea = find_lea_xrefs(pe)

floss/language/utils.py

@@ -473,6 +473,48 @@ def get_struct_string_candidates(pe: pefile.PE) -> Iterable[StructString]:
             # dozens of seconds or more (suspect many minutes).
 
 
+def get_raw_xrefs_rdata_i386(pe: pefile.PE, buf: bytes) -> Iterable[VA]:
+    """
+    scan for raw xrefs in .rdata section.
+    raw xrefs are 32-bit absolute addresses to strings in .rdata section (i386).
+    They are not encoded as struct String instances.
+
+    example:
+    .rdata:004D6234                 dd offset unk_4C85C9
+    .rdata:004D6238                 dd offset unk_4C85C3
+    .rdata:004D623C                 dd offset unk_4C85BB
+    .rdata:004D6240                 dd offset unk_4C85B3
+
+    From the disassembly, they are called as follows:
+    .text:00498E56                 push    ds:off_4D61E0[ecx*4]
+
+    The above are not struct String instances, but are references to strings in .rdata section.
+    They can be used to divide the string blobs into smaller chunks.
+    """
+    format = "I"
+
+    if not buf:
+        return
+
+    low, high = get_image_range(pe)
+
+    # using array module as a high-performance way to access the data as fixed-sized words.
+    words = iter(array.array(format, buf))
+
+    last = next(words)
+    for current in words:
+        address = last
+        last = current
+
+        if address == 0x0:
+            continue
+
+        if not (low <= address < high):
+            continue
+
+        yield address
+
+
 def get_extract_stats(
     pe: pefile, all_ss_strings: List[StaticString], lang_strings: List[StaticString], min_len: int, min_blob_len=0
 ) -> float:

tests/test_language_extract_rust.py

@@ -80,3 +80,21 @@ def test_push(request, string, offset, encoding, rust_strings):
 )
 def test_mov_jmp(request, string, offset, encoding, rust_strings):
     assert StaticString(string=string, offset=offset, encoding=encoding) in request.getfixturevalue(rust_strings)
+
+
+@pytest.mark.parametrize(
+    "string,offset,encoding,rust_strings",
+    [
+        # .rdata:004BFA48                 dd offset unk_4BA13A
+        # .rdata:004BFA4C                 dd offset unk_4BA100
+        pytest.param("Invalid branch target in DWARF expression", 0xB813A, StringEncoding.UTF8, "rust_strings32"),
+        pytest.param(
+            "Expected to find an FDE pointer, but found a CIE pointer instead.",
+            0xB8163,
+            StringEncoding.UTF8,
+            "rust_strings32",
+        ),
+    ],
+)
+def test_raw_xrefs(request, string, offset, encoding, rust_strings):
+    assert StaticString(string=string, offset=offset, encoding=encoding) in request.getfixturevalue(rust_strings)