create normalize_path: Also normalizes /./ into /

Author: bitterpanda63

aikido_zen/vulnerabilities/path_traversal/detect_path_traversal_test.py

@@ -106,3 +106,29 @@ def test_does_not_absolute_path_inside_another_folder():
 
 def test_disable_checkPathStart():
     assert detect_path_traversal("/etc/passwd", "/etc/passwd", False) is False
+
+
+def test_current_directory_references():
+    """/./ should be normalized to /"""
+    assert detect_path_traversal("/./etc/passwd", "/./etc") is True
+    assert detect_path_traversal("/etc/./passwd", "/etc") is True
+    assert detect_path_traversal("/etc/./passwd", "/etc/./") is True
+    assert detect_path_traversal("/./etc/passwd", "/./etc/passwd") is True
+    assert detect_path_traversal("/etc/./passwd", "/etc/./passwd") is True
+    assert detect_path_traversal("/./etc/./passwd", "/./etc/./passwd") is True
+    # Multiple /./ sequences
+    assert detect_path_traversal("/././etc/passwd", "/././etc") is True
+    assert detect_path_traversal("/etc/././passwd", "/etc/././passwd") is True
+
+
+def test_path_normalization():
+    """Paths with multiple slashes and /./ should be normalized and detected"""
+    assert detect_path_traversal("//etc//passwd", "/etc") is True
+    assert detect_path_traversal("/./etc/./passwd", "/etc") is True
+    assert detect_path_traversal("/././etc/passwd", "/etc") is True
+    # Paths without leading slash are not unsafe
+    assert detect_path_traversal("etc/passwd", "etc") is False
+    assert detect_path_traversal("", "") is False
+    # Combined slashes and dot: ///.///etc/passwd should normalize to /etc/passwd
+    assert detect_path_traversal("///.///etc/passwd", "///.///etc") is True
+    assert detect_path_traversal("///.///etc/passwd", "///.///etc/passwd") is True

aikido_zen/vulnerabilities/path_traversal/unsafe_path_start.py

@@ -1,5 +1,9 @@
 """Exports the function starts_with_unsafe_path"""
 
+import regex as re
+
+CURRENT_DIR_PATTERN = re.compile(r"/(\./)+")
+
 linux_root_folders = [
     "/bin/",
     "/boot/",
@@ -31,8 +35,8 @@
 
 def starts_with_unsafe_path(file_path, user_input):
     """Check if the file path starts with any dangerous paths and the user input."""
-    path_parsed = ensure_one_leading_slash(file_path.lower())
-    input_parsed = ensure_one_leading_slash(user_input.lower())
+    path_parsed = normalize_path(file_path)
+    input_parsed = normalize_path(user_input)
 
     for dangerous_start in dangerous_path_starts:
         if path_parsed.startswith(dangerous_start) and path_parsed.startswith(
@@ -43,7 +47,16 @@ def starts_with_unsafe_path(file_path, user_input):
     return False
 
 
-def ensure_one_leading_slash(path: str) -> str:
-    if path.startswith("/"):
-        return "/" + path.lstrip("/")
-    return path
+def normalize_path(path: str) -> str:
+    """Normalizes a path by lowercasing, removing /./ and removing consecutive slashes"""
+    if not path:
+        return path
+
+    normalized = path.lower()
+
+    # Matches /./ or /././ or /./././ etc. (one or more ./ sequences after a /)
+    normalized = CURRENT_DIR_PATTERN.sub("/", normalized)
+
+    # Merge consecutive slashes since these don't change where you are in the path.
+    normalized = re.sub(r"/+", "/", normalized)
+    return normalized