type: attack-pattern
spec_version: 2.1
id: attack-pattern--b46a801b-fd98-491c-a25a-bca25d6e3001
created: 2021-06-03T18:44:29.770Z
created_by_ref: identity--c78cb6e5-0c4b-4611-8297-d1b8b55e40b5
revoked: no
external_references: source_name: mitre-attack
url: https://attack.mitre.org/techniques/T1505/004
external_id: T1505.004
source_name: Dell TG-3390
description: Dell SecureWorks Counter Threat Unit Threat Intelligence. (2015, August 5). Threat Group-3390 Targets Organizations for Cyberespionage. Retrieved August 18, 2018.
url: https://www.secureworks.com/research/threat-group-3390-targets-organizations-for-cyberespionage
source_name: Unit 42 RGDoor Jan 2018
description: Falcone, R. (2018, January 25). OilRig uses RGDoor IIS Backdoor on Targets in the Middle East. Retrieved July 6, 2018.
url: https://researchcenter.paloaltonetworks.com/2018/01/unit42-oilrig-uses-rgdoor-iis-backdoor-targets-middle-east/
source_name: Trustwave IIS Module 2013
description: Grunzweig, J. (2013, December 9). The Curious Case of the Malicious IIS Module. Retrieved June 3, 2021.
url: https://www.trustwave.com/en-us/resources/blogs/spiderlabs-blog/the-curious-case-of-the-malicious-iis-module/
source_name: ESET IIS Malware 2021
description: Hromcová, Z., Cherepanov, A. (2021). Anatomy of Native IIS Malware. Retrieved September 9, 2021.
url: https://i.blackhat.com/USA21/Wednesday-Handouts/us-21-Anatomy-Of-Native-Iis-Malware-wp.pdf
source_name: IIS Backdoor 2011
description: Julien. (2011, February 2). IIS Backdoor. Retrieved June 3, 2021.
url: https://web.archive.org/web/20170106175935/http:/esec-lab.sogeti.com/posts/2011/02/02/iis-backdoor.html
source_name: Microsoft IIS Modules Overview 2007
description: Microsoft. (2007, November 24). IIS Modules Overview. Retrieved June 17, 2021.
url: https://docs.microsoft.com/en-us/iis/get-started/introduction-to-iis/iis-modules-overview
source_name: Microsoft ISAPI Extension All Incoming 2017
description: Microsoft. (2017, June 16). Intercepting All Incoming IIS Requests. Retrieved June 3, 2021.
url: https://docs.microsoft.com/en-us/previous-versions/iis/6.0-sdk/ms525696(v=vs.90)
source_name: Microsoft ISAPI Extension Overview 2017
description: Microsoft. (2017, June 16). ISAPI Extension Overview. Retrieved June 3, 2021.
url: https://docs.microsoft.com/en-us/previous-versions/iis/6.0-sdk/ms525172(v=vs.90)
source_name: Microsoft ISAPI Filter Overview 2017
description: Microsoft. (2017, June 16). ISAPI Filter Overview. Retrieved June 3, 2021.
url: https://docs.microsoft.com/en-us/previous-versions/iis/6.0-sdk/ms524610(v=vs.90)
source_name: MMPC ISAPI Filter 2012
description: MMPC. (2012, October 3). Malware signed with the Adobe code signing certificate. Retrieved June 3, 2021.
url: https://web.archive.org/web/20140804175025/http:/blogs.technet.com/b/mmpc/archive/2012/10/03/malware-signed-with-the-adobe-code-signing-certificate.aspx
object_marking_refs: marking-definition--fa42a846-8d90-4e51-bc29-71d5b4802168
modified: 2025-10-24T17:49:15.437Z
name: IIS Components
description: Adversaries may install malicious components that run on Internet Information Services (IIS) web servers to establish persistence. IIS provides several mechanisms to extend the functionality of the web servers. For example, Internet Server Application Programming Interface (ISAPI) extensions and filters can be installed to examine and/or modify incoming and outgoing IIS web requests. Extensions and filters are deployed as DLL files that export three functions: Get{Extension/Filter}Version, Http{Extension/Filter}Proc, and (optionally) Terminate{Extension/Filter}. IIS modules may also be installed to extend IIS web servers.(Citation: Microsoft ISAPI Extension Overview 2017)(Citation: Microsoft ISAPI Filter Overview 2017)(Citation: IIS Backdoor 2011)(Citation: Trustwave IIS Module 2013)

Adversaries may install malicious ISAPI extensions and filters to observe and/or modify traffic, execute commands on compromised machines, or proxy command and control traffic. ISAPI extensions and filters may have access to all IIS web requests and responses. For example, an adversary may abuse these mechanisms to modify HTTP responses in order to distribute malicious commands/content to previously comprised hosts.(Citation: Microsoft ISAPI Filter Overview 2017)(Citation: Microsoft ISAPI Extension Overview 2017)(Citation: Microsoft ISAPI Extension All Incoming 2017)(Citation: Dell TG-3390)(Citation: Trustwave IIS Module 2013)(Citation: MMPC ISAPI Filter 2012)

Adversaries may also install malicious IIS modules to observe and/or modify traffic. IIS 7.0 introduced modules that provide the same unrestricted access to HTTP requests and responses as ISAPI extensions and filters. IIS modules can be written as a DLL that exports RegisterModule, or as a .NET application that interfaces with ASP.NET APIs to access IIS HTTP requests.(Citation: Microsoft IIS Modules Overview 2007)(Citation: Trustwave IIS Module 2013)(Citation: ESET IIS Malware 2021)
kill_chain_phases: kill_chain_name: mitre-attack
phase_name: persistence
x_mitre_attack_spec_version: 3.2.0
x_mitre_contributors: Wes Hurd
x_mitre_deprecated: no
x_mitre_domains: enterprise-attack
x_mitre_is_subtechnique: yes
x_mitre_modified_by_ref: identity--c78cb6e5-0c4b-4611-8297-d1b8b55e40b5
x_mitre_platforms: Windows
x_mitre_version: 1.1