Sync RTA Base64 Shebang Payload Decoded via Built-in Utility (#4181)

Co-authored-by: shashank-elastic <[email protected]>

(cherry picked from commit 2e1daee)

Author: protectionsmachine

rta/linux_defense_evasion_shebang_decoded_via_builtin_utility.py

@@ -0,0 +1,40 @@
+# Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+# or more contributor license agreements. Licensed under the Elastic License
+# 2.0; you may not use this file except in compliance with the Elastic License
+# 2.0.
+
+import sys
+from . import RtaMetadata, common
+
+metadata = RtaMetadata(
+    uuid="074901e7-118b-4536-bbed-0e57c319ba2a",
+    platforms=["linux"],
+    endpoint=[
+        {
+            "rule_name": "Base64 Shebang Payload Decoded via Built-in Utility",
+            "rule_id": "e659b4b9-5bbf-4839-96b9-b489334b4ca1",
+        },
+    ],
+    techniques=["T1027", "T1140", "T1059", "T1204"],
+)
+
+
+@common.requires_os(*metadata.platforms)
+def main() -> None:
+    common.log("Creating a fake executable..")
+    masquerade = "/tmp/base64"
+
+    source = common.get_path("bin", "linux.ditto_and_spawn")
+    common.copy_file(source, masquerade)
+    common.log("Granting execute permissions...")
+    common.execute(["chmod", "+x", masquerade])
+
+    commands = [masquerade, '-d', 'IyEvdXNyL2Jpbi9weXRob24']
+    common.execute([*commands], timeout=5, kill=True)
+    common.log("Cleaning...")
+    common.remove_file(masquerade)
+    common.log("Simulation successfull!")
+
+
+if __name__ == "__main__":
+    sys.exit(main())