Create signature for DLL sideloading

modules/signatures/windows/dll_sideloading.py

@@ -0,0 +1,64 @@
+# Copyright (C) 2025 Kevin Ross
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+from lib.cuckoo.common.abstracts import Signature
+
+class DLLLoadSuspiciousDirectory(Signature):
+    name = "dllload_suspicious_directory"
+    description = "A DLL was loaded from a suspicious directory"
+    severity = 2
+    confidence = 50
+    categories = ["side loading"]
+    authors = ["Kevin Ross"]
+    minimum = "1.3"
+    evented = True
+    enabled = True
+    ttps = ["T1574"]  # MITRE v6,7,8
+    mbcs = ["F0015"]
+
+    def __init__(self, *args, **kwargs):
+        Signature.__init__(self, *args, **kwargs)
+        self.ret = False
+        # Any exclusions added to this list needs to be in lower format.
+        self.ignore_directories = [
+            "c:\\windows\\system32\\",
+            "c:\\windows\\syswow64\\",
+            "c:\\windows\\",
+            "c:\\windows\\winsxs\\",
+            "c:\\program files\\",
+            "c:\\program files (x86)\\",
+            "c:\\programdata\\",
+        ]
+
+    filter_apinames = set(["DllLoadNotification"])
+
+    def on_call(self, call, process):
+        if not call["status"]:
+            return None
+
+        if call["api"] == "DllLoadNotification":
+            notificationreason = self.get_argument(call, "NotificationReason")
+            dllname = self.get_argument(call, "DllName")
+            if notificationreason == "load":
+                pname = process["process_name"].lower()
+                dllnamelower = dllname.lower()
+                is_ignored = any(dllnamelower.startswith(d) for d in self.ignore_directories)
+                if not is_ignored:
+                    self.mark_call()
+                    self.data.append({"suspicious_dll_load": "Process %s loaded a DLL from a suspicious directory, this is possibly indicative of DLL side loading/search order hijacking" % (pname)})
+                    self.ret = True
+
+    def on_complete(self):
+        return self.ret