Dirk-jan Mollema
Security Expert And Founder at Outsider Security
The Hague, South Holland, Netherlands
Summary
🤩
Rockstar🎓
Top SchoolDirk-jan Mollema is a security expert and founder based in The Hague with 13 years of experience specializing in Active Directory, Kerberos, and offensive/defensive tooling. He has deep hands-on expertise building and maintaining widely used open-source security tools—authoring projects like ldapdomaindump, adidnsdump and contributions to Impacket and ldap3 that demonstrate protocol-level mastery and exploit development such as a Zerologon PoC. As Principal Security Expert at Fox-IT and now leading Outsider Security, he blends practical attack research with secure tooling for blue teams and red teams alike. Dirk-jan’s work shows a pattern of improving core LDAP/Kerberos stacks, adding resilient error handling and modern Python3 compatibility across projects. Uncommonly for tool authors, he focuses both on data ingestors for graph tools (BloodHound.py) and subtle protocol controls (MS security descriptor controls), reflecting a rare mix of defensive visibility and offensive creativity.
13 years of coding experience
6 years of employment as a software developer
TU Delft
Github Skills (28)
azuread10
ldap10
dce10
back-end-development10
python10
kerberos10
drpc10
user-authentication10
authentication10
ntlm10
security10
exploit10
active-directory10
rpc10
dns10
Programming languages (13)
Github contributions (5)
dirkjanm/ROADtools
Apr 2020 - Dec 2022
A collection of Azure AD/Entra tools for offensive and defensive security purposes
Role in this project:
Back-end Developer
Back-end DeveloperContributions:133 commits, 42 PRs, 230 pushes in 2 years 8 months
Contributions summary:Dirk-jan primarily focused on fixing and improving existing code. The user made changes related to database interactions, including adjustments to the schema and setup.py file. They also contributed to the backend by modifying code related to data gathering, server functionality, and BloodHound plugin integrations which included writing code in python.
pythonsecuritydefensive-securitydefensiveoffensive
dirkjanm/BloodHound.py
Feb 2018 - Jan 2023
A Python based ingestor for BloodHound
Role in this project:Back-end Developer
Back-end DeveloperContributions:196 commits, 75 PRs, 187 pushes in 4 years 11 months
Contributions summary:Dirk-jan's commits primarily involve the development of the `bloodhound.py` project, a Python-based ingestor for BloodHound. The changes focus on enhancing and maintaining the Active Directory (AD) data processing components within the project, specifically the `bloodhound/ad.py` file. The user implemented improvements to exception handling, and functionality such as trusts enumeration. The changes also included transitioning the LDAP connection to the `ldap3` library.
pythoningestoractivedirectorypython3bloodhound
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