active directory

Not A Security Boundary: Breaking Forest Trusts

Published November 28, 2018 by harmj0y

For years Microsoft has stated that the forest was the security boundary in Active Directory. For example, Microsoft’s “What Are Domains and Forests?” document (last updated in 2014) has a “Forests as Security Boundaries” section which states (emphasis added): Each forest is a single instance of the directory, the top-level Active Directory container, and a security boundary for all objects that are located in the forest. This security boundary defines the scope of authority of the administrators. In general, a security boundary is defined by the top-level container for which no administrator external to the container can take control away…

Remote Hash Extraction On Demand Via Host Security Descriptor Modification

Published April 10, 2018 by harmj0y

This is the long overdue follow-up to the “An ACE in the Hole: Stealthy Host Persistence via Security Descriptors” presentation (slides and video) that @tifkin_, @enigma0x3, and I gave at DerbyCon last year. This past weekend we gave a talk at @Sp4rkCon titled “The Unintended Risks of Trusting Active Directory” that explored combining our host-based security descriptor research with the work that @_wald0 and I detailed at Black Hat and DEF CON last year on Active Directory security descriptor backdooring. One of the more interesting case studies at both DerbyCon and Sp4rkCon involved a host-based security descriptor modification primitive that…

Hunting With Active Directory Replication Metadata

Published September 6, 2017 by harmj0y

With the recent release of BloodHound’s ACL Attack Path Update as well as the work on Active Directory DACL backdooring by @_wald0 and myself (whitepaper here), I started to investigate ACL-based attack paths from a defensive perspective. Sean Metcalf has done some great work concerning Active Directory threat hunting (see his 2017 BSides Charm “Detecting the Elusive: Active Directory Threat Hunting” presentation) and I wanted to show how replication metadata can help in detecting this type of malicious activity. Also, after this post had been drafted, Grégory LUCAND pointed out to me the extensive article (in French) he authored on…

Command and Control Using Active Directory

Published August 15, 2016 by harmj0y

‘Exotic’ command and control (C2) channels always interest me. As defenses start to get more sophisticated, standard channels that have been stealthy before (like DNS) may start to lose their efficacy. I’m always on the lookout for non-obvious, one-way (or ideally two-way) communication methods. This post will cover a proof of concept for an internal C2 approach that uses standard Active Directory object properties in a default domain setup. Active Directory Property Sets This dawned on me when reviewing access control list entry information during training prep. In a default domain setup, there is a set of ACLs for user objects that apply to the user itself, defined…

Tag: active directory

Not A Security Boundary: Breaking Forest Trusts

Remote Hash Extraction On Demand Via Host Security Descriptor Modification

Hunting With Active Directory Replication Metadata

A Pentester’s Guide to Group Scoping

Command and Control Using Active Directory