Adversaries may modify Group Policy Objects (GPOs) to subvert the intended discretionary access controls for a domain, usually with the intention of escalating privileges on the domain. Group policy allows for centralized management of user and computer settings in Active Directory (AD). GPOs are containers for group policy settings made up of files stored within a predictable network path `\<DOMAIN>\SYSVOL\<DOMAIN>\Policies\`.(Citation: TechNet Group Policy Basics)(Citation: ADSecurity GPO Persistence 2016) 

Like other objects in AD, GPOs have access controls associated with them. By default all user accounts in the domain have permission to read GPOs. It is possible to delegate GPO access control permissions, e.g. write access, to specific users or groups in the domain.

Malicious GPO modifications can be used to implement many other malicious behaviors such as [Scheduled Task/Job](https://attack.mitre.org/techniques/T1053), [Disable or Modify Tools](https://attack.mitre.org/techniques/T1562/001), [Ingress Tool Transfer](https://attack.mitre.org/techniques/T1105), [Create Account](https://attack.mitre.org/techniques/T1136), [Service Execution](https://attack.mitre.org/techniques/T1569/002),  and more.(Citation: ADSecurity GPO Persistence 2016)(Citation: Wald0 Guide to GPOs)(Citation: Harmj0y Abusing GPO Permissions)(Citation: Mandiant M Trends 2016)(Citation: Microsoft Hacking Team Breach) Since GPOs can control so many user and machine settings in the AD environment, there are a great number of potential attacks that can stem from this GPO abuse.(Citation: Wald0 Guide to GPOs)

For example, publicly available scripts such as <code>New-GPOImmediateTask</code> can be leveraged to automate the creation of a malicious [Scheduled Task/Job](https://attack.mitre.org/techniques/T1053) by modifying GPO settings, in this case modifying <code>&lt;GPO_PATH&gt;\Machine\Preferences\ScheduledTasks\ScheduledTasks.xml</code>.(Citation: Wald0 Guide to GPOs)(Citation: Harmj0y Abusing GPO Permissions) In some cases an adversary might modify specific user rights like SeEnableDelegationPrivilege, set in <code>&lt;GPO_PATH&gt;\MACHINE\Microsoft\Windows NT\SecEdit\GptTmpl.inf</code>, to achieve a subtle AD backdoor with complete control of the domain because the user account under the adversary's control would then be able to modify GPOs.(Citation: Harmj0y SeEnableDelegationPrivilege Right)
Group Policy Modification
source_name: mitre-attack  url: https://attack.mitre.org/techniques/T1484/001  external_id: T1484.001     source_name: Mandiant M Trends 2016  description: Mandiant. (2016, February 25). Mandiant M-Trends 2016. Retrieved March 5, 2019.  url: https://www.fireeye.com/content/dam/fireeye-www/current-threats/pdfs/rpt-mtrends-2016.pdf     source_name: ADSecurity GPO Persistence 2016  description: Metcalf, S. (2016, March 14). Sneaky Active Directory Persistence #17: Group Policy. Retrieved March 5, 2019.  url: https://adsecurity.org/?p=2716     source_name: Microsoft Hacking Team Breach  description: Microsoft Secure Team. (2016, June 1). Hacking Team Breach: A Cyber Jurassic Park. Retrieved March 5, 2019.  url: https://www.microsoft.com/security/blog/2016/06/01/hacking-team-breach-a-cyber-jurassic-park/     source_name: Wald0 Guide to GPOs  description: Robbins, A. (2018, April 2). A Red Teamer’s Guide to GPOs and OUs. Retrieved March 5, 2019.  url: https://wald0.com/?p=179     source_name: Harmj0y Abusing GPO Permissions  description: Schroeder, W. (2016, March 17). Abusing GPO Permissions. Retrieved March 5, 2019.  url: http://www.harmj0y.net/blog/redteaming/abusing-gpo-permissions/     source_name: Harmj0y SeEnableDelegationPrivilege Right  description: Schroeder, W. (2017, January 10). The Most Dangerous User Right You (Probably) Have Never Heard Of. Retrieved March 5, 2019.  url: http://www.harmj0y.net/blog/activedirectory/the-most-dangerous-user-right-you-probably-have-never-heard-of/     source_name: TechNet Group Policy Basics  description: srachui. (2012, February 13). Group Policy Basics – Part 1: Understanding the Structure of a Group Policy Object. Retrieved March 5, 2019.  url: https://blogs.technet.microsoft.com/musings_of_a_technical_tam/2012/02/13/group-policy-basics-part-1-understanding-the-structure-of-a-group-policy-object/     