sigma-rules/rta/rundll32_javascript_callback.py

# 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.

# Name: RunDLL32 Javascript Callback
# RTA: rundll32_javascript_callback.py
# signal.rule.name: Local Service Commands
# signal.rule.name: Potential Modification of Accessibility Binaries
# ATT&CK: T1085
# Description: Executes javascript code with an AJAX call via RunDll32.exe

from . import common
from . import RtaMetadata


metadata = RtaMetadata(
    uuid="75687622-2e75-4612-b213-a31f923efdd4",
    platforms=["windows"],
    endpoint=[],
    siem=[],
    techniques=[]
)


@common.requires_os(*metadata.platforms)
def main():
    common.log("RunDLL32 with Javascript Callback")
    server, ip, port = common.serve_web()
    common.clear_web_cache()

    url = "http://%s:%d" % (ip, port)
    rundll32 = "rundll32.exe"
    js = """
        'javascript:"\..\mshtml,RunHTMLApplication ";'
        'var%20xhr=new%20ActiveXObject("Msxml2.XMLHttp.6.0");,'
        'xhr.open("GET", "{url}",false);xhr.send();'
    """.format(
        url=url
    )
    packed_js = "".join(s.strip() for s in js.splitlines())

    common.execute([rundll32, packed_js])
    server.shutdown()


if __name__ == "__main__":
    exit(main())